Skin Health: The Complete Guide

Key numbers at a glance

How your skin works

Your skin is your largest organ, and most of its work happens in a layer thinner than a sheet of paper. The outermost part of the epidermis, the stratum corneum, is made of flattened dead cells held together by fats, often compared to bricks and mortar. This barrier keeps water in and irritants, allergens and microbes out. When it is intact, skin feels smooth and comfortable; when it is damaged, water escapes, skin becomes dry and tight, and substances that would normally bounce off can get in and trigger inflammation.

Beneath the epidermis lies the dermis, which contains collagen and elastic fibers that give skin its strength and spring, along with blood vessels, nerves, sweat glands, oil glands and hair follicles. Pigment cells called melanocytes sit at the base of the epidermis and produce melanin, which gives skin its color and absorbs some ultraviolet (UV) light. Melanocytes are also where melanoma, the most dangerous common skin cancer, begins.

Skin renews itself continuously, with new cells moving up from the base of the epidermis and shedding from the surface over a few weeks. It also helps control body temperature through sweating and blood flow, makes vitamin D in sunlight, and hosts an immune system of its own. Many skin conditions are, at root, a disturbance in one of these jobs: a weak barrier in eczema, overactive renewal in psoriasis, blocked follicles in acne, or DNA damage from UV in skin cancer.

Why skin health matters

Skin cancer is the most common cancer in the United States, and most cases are linked to UV exposure from the sun or tanning beds. That makes it one of the most preventable cancers, and, because it grows where you can see it, one of the easiest to catch early. Melanoma found early is usually treatable with simple surgery; found late, it is much harder to treat.

Beyond cancer, chronic skin conditions affect sleep, work, mood and confidence. Persistent itch can be as disruptive as chronic pain, and visible conditions such as acne and psoriasis are linked to anxiety and low mood. Skin can also signal problems elsewhere: itch without a rash can be the first sign of liver, kidney or thyroid disease, and psoriasis is associated with joint disease and higher cardiovascular risk. Looking after your skin, and paying attention to it, is part of looking after your whole health.

The common skin conditions

Most skin problems people bring to a doctor fall into a handful of familiar conditions. Each has its own cause and its own approach, and a common thread runs through several of them: treatment often fails not because it is the wrong treatment but because it is used too sparingly, for too short a time, or stopped as soon as things look better.

Eczema (atopic dermatitis)

Eczema is a chronic inflammatory condition that causes dry, itchy, inflamed skin, often in the creases of the elbows and knees in older children and adults, and on the face and outer limbs in babies. It runs in families alongside asthma and hay fever and involves a weakened skin barrier. It is managed rather than cured. The mainstay of care is moisturizer, used generously and often, including when skin looks clear, with topical steroids or other prescribed medicines for flares. Harsh soaps, heat, sweat and some fabrics are common triggers.

Acne

Acne happens when hair follicles become blocked with oil and dead skin and then inflamed, producing blackheads, whiteheads, pimples and sometimes deep, painful nodules and cysts on the face, chest and back. It is not caused by poor hygiene or dirt, and scrubbing makes it worse. Effective treatment exists for every severity, including the kind that scars, but almost all acne treatments take 6 to 8 weeks or longer before you can judge whether they are working.

Psoriasis

Psoriasis is an immune-mediated condition in which skin cells are produced too quickly, building up into thickened, scaly plaques, often on the elbows, knees, scalp and lower back. It is not contagious. It affects more than the skin: a significant minority of people develop psoriatic arthritis, and psoriasis is associated with raised cardiovascular risk. Smoking, alcohol and excess weight all affect severity, and regular checkups should include blood pressure, cholesterol and blood glucose.

Fungal infections

Athlete's foot, ringworm and nail fungus are caused by fungi that thrive in warm, damp places and spread on shared floors, towels and footwear. Skin infections usually respond to over-the-counter antifungal creams, while nail infections often need prescription treatment for months. The most common reason for failure is stopping as soon as the skin looks better. Using a steroid cream alone on a fungal rash can make it spread, so if you are not sure what a rash is, get it checked before treating it.

Dry skin and itching

Dry skin is skin that has lost water and oils from its barrier, becoming rough, tight or flaky. Most cases are caused or worsened by washing habits — hot water, long showers and harsh soap — plus indoor heating and wind, which makes them unusually easy to improve. Itching often comes with dry skin or a rash, but itch without any visible rash deserves attention, because it can be the first sign of a condition elsewhere in the body.

Risk factors you can and cannot change

For skin cancer, the fixed risk factors include fair skin that burns easily, light hair and eyes, a large number of moles or unusual-looking moles, a personal or family history of skin cancer, and older age. A weakened immune system, for example after an organ transplant, also raises risk substantially. People with darker skin have a lower risk of skin cancer but are not immune, and when it does occur it is more often found late, sometimes in places that get little sun, such as the palms, soles and under the nails.

The biggest modifiable risk is UV exposure. Sunburn, especially in childhood and adolescence, raises melanoma risk for life, and cumulative exposure over decades drives most basal cell and squamous cell cancers as well as most visible skin aging on exposed areas. Indoor tanning raises skin cancer risk and is not a safe alternative to the sun. Smoking speeds up skin aging and is linked to worse psoriasis.

For other skin conditions, family history matters for eczema and psoriasis, and hormones play a large part in acne. Modifiable triggers include harsh soaps, fragranced products, very hot water, low humidity, sweat, tight synthetic clothing and, for fungal infections, damp footwear and shared surfaces. Some medicines also affect the skin, from those that increase sun sensitivity to steroid tablets that thin it over time, so it is worth asking your pharmacist whether anything you take changes how your skin behaves.

Skin cancer: warning signs and self-checks

Melanoma often starts as a new spot or a change in an existing mole. Dermatologists use the ABCDEs to describe what to look for: Asymmetry (one half does not match the other), Border (irregular, ragged or blurred edges), Color (more than one color or uneven shading), Diameter (larger than about 6 mm, or 1/4 inch, the size of a pencil eraser, though melanomas can be smaller), and Evolving (any change in size, shape, color or symptoms). Of these, change over weeks or months is the most important single feature.

Another useful rule is the "ugly duckling" sign: a mole that looks different from all your others deserves a closer look, even if it does not tick any ABCDE box. Itching, bleeding, crusting or inflammation in a mole are also reasons to get it checked. The other common skin cancers, basal cell and squamous cell carcinoma, look different from melanoma: think of a sore that does not heal, a pearly or shiny bump, a scaly or crusted patch, or a new growth that bleeds easily.

A self-check takes a few minutes. In good light, use a full-length mirror and a hand mirror to look at all of your skin, including your scalp, the backs of your legs, the soles of your feet, between your toes and under your nails. Ask a partner or family member to check your back. Photographing anything you are unsure about, with a coin or ruler for scale, lets you compare later and gives your doctor useful information. Do not rely on phone apps to decide whether a mole needs checking.

• A new mole or spot in adulthood, especially if it is growing
• A mole that is changing in size, shape or color
• A spot with an irregular edge or more than one color
• Itching, bleeding, crusting or inflammation in a mole
• A sore, lump or scaly patch that does not heal, or heals and comes back
• A dark streak under a nail that is not explained by an injury

How skin problems are checked

Most skin conditions are diagnosed by looking. Your doctor or a dermatologist will examine the skin, often with a handheld magnifying light called a dermatoscope, and ask about how it started, what makes it worse, what you have tried and whether anyone else in the family is affected. For eczema, acne and psoriasis, the diagnosis is usually made from the appearance and history alone.

When there is doubt, simple tests help. A scraping of skin or a clipping of nail can be examined in a lab to confirm a fungal infection before months of treatment begin. A swab can identify bacteria in an infected patch. Patch testing, in which small amounts of common allergens are taped to the back for a few days, can identify a contact allergy behind a stubborn rash. For a suspicious mole or growth, a biopsy — removing all or part of it under local anesthetic for examination under a microscope — is the only way to confirm or rule out cancer.

Skin cancer screening

The US Preventive Services Task Force has found insufficient evidence to recommend for or against routine full-body skin exams by a clinician for adults without symptoms. That is not a reason to ignore your skin. It means the emphasis falls on knowing your own skin, checking it regularly and getting any new or changing spot seen promptly. People at higher risk — those with many or unusual moles, a previous skin cancer, a strong family history or a weakened immune system — should ask a dermatologist how often they should be checked.

Sun protection that works

Good sun protection is layered, and sunscreen is the last layer rather than the first. Start by planning around the strongest UV, roughly 10 a.m. to 4 p.m., and seek shade when you can. The UV Index, published daily by the EPA and in most weather apps, tells you how strong UV will be where you are; at 3 or above, protection matters. Clouds, cool days, water, sand and snow do not reduce your need for protection, and some of those surfaces reflect UV back at you.

Clothing is the most reliable barrier because it does not wear off. Long sleeves, long pants and a wide-brimmed hat that shades your face, ears and neck protect far more consistently than lotion. Tightly woven or darker fabrics block more UV, and some clothing carries an ultraviolet protection factor (UPF) label. Sunglasses that block UV protect your eyes and the thin skin around them.

For skin you cannot cover, the American Academy of Dermatology recommends a broad-spectrum, water-resistant sunscreen with SPF 30 or higher. Broad-spectrum means it protects against both UVA, which ages skin, and UVB, which burns. Most people apply far too little: an adult needs about 1 ounce, roughly enough to fill a shot glass, to cover the body. Apply it about 15 minutes before going out and reapply every 2 hours, and after swimming or sweating. Water-resistant products are tested for 40 or 80 minutes in water, and no sunscreen is waterproof or sweatproof.

• Check the UV Index and plan outdoor time around midday
• Use shade and clothing first, sunscreen on whatever remains exposed
• Choose broad-spectrum, water-resistant, SPF 30 or higher
• Apply generously, including ears, neck, tops of feet and scalp partings
• Reapply every 2 hours and after swimming or sweating
• Avoid tanning beds and sunlamps entirely

What about vitamin D?

Your skin makes vitamin D in sunlight, but you do not need to risk sunburn or skin damage to get enough. Dermatologists advise getting vitamin D from food — fatty fish, fortified milk and fortified cereals — and, where needed, a supplement. The recommended dietary allowance for adults up to 70 is 15 mcg (600 IU) a day. If you have very little sun exposure or darker skin, ask your doctor whether a supplement makes sense for you.

Everyday skin care that helps

Healthy skin does not need a long routine. For most people, a gentle cleanser, a moisturizer and sun protection do most of the work, and expensive products rarely add much beyond those basics. The habits that matter most are how you wash and how you moisturize, because those decide whether the barrier stays intact. Adding many active products at once is a common cause of irritation, so introduce one new product at a time.

Keep showers and baths short — about 5 to 10 minutes — in warm rather than hot water, and use a gentle, fragrance-free cleanser instead of harsh soap or bubble bath. Pat skin dry rather than rubbing, then apply moisturizer within a few minutes, while the skin is still damp, to trap water in. Ointments and creams are more effective than lotions for very dry skin; ointments are greasier but often the most soothing. In cold, dry weather, moisturize more often and consider a humidifier indoors. Avoid scrubbing with rough washcloths or loofahs.

For itch, keep the skin cool and moisturized, keep nails short to limit damage from scratching, and remove irritants such as fragranced detergents and fabric softeners. Scratching feeds an itch-scratch cycle that thickens and inflames the skin, so breaking it — with moisturizer, cool compresses and treatment of any underlying rash — matters. Hot water feels good on itchy skin for a moment but makes itch worse afterward.

Caring for cuts and scrapes

Most minor wounds heal well with simple care. Wash your hands, then rinse the wound under clean running water, which is adequate for minor cuts; antiseptic solutions and hydrogen peroxide are rarely needed and can damage healing tissue if used repeatedly. Cover the wound with a clean bandage and keep it moist, for example with petroleum jelly, because covered wounds heal better than those left to scab in the air. Change the bandage when it is wet or dirty.

Check your tetanus status for anything dirty, deep or caused by an animal. Adults need a tetanus booster every 10 years, and for a dirty or deep wound a booster is recommended if it has been 5 years or more. A wound that becomes more painful after the second day, with spreading redness, swelling, pus, fever or a red streak, may be infected and needs same-day care.

Treatment and care options

Skin treatments work only when used properly, and under-treatment is far more common than over-treatment. A cream applied too thinly, too rarely, or stopped after a few days will often appear not to work. When you are given a treatment, ask how much to use, how often, for how long, and what to expect along the way. Ask, too, what to do if it has not helped by a certain point, so you are not left guessing.

Topical steroids, used well

Topical steroids are the main treatment for eczema flares and are widely used in psoriasis. They come in different strengths, matched to the severity of the rash and the body area: weaker ones for the face and skin folds, stronger ones for thick skin on the hands, feet or trunk. Fear of steroid creams leads many people to use too little, which prolongs flares. The fingertip unit is a standard measure: a line of cream squeezed from the tip of an adult finger to the first crease, which covers an area about the size of two adult palms. Use the strength and amount prescribed, for as long as advised, and do not stop strong steroid creams abruptly without guidance.

Acne treatments

First-line options are topical retinoids and benzoyl peroxide, often combined; some are available over the counter. Antibiotics, whether creams or tablets, are not used alone, to limit resistance. For severe, scarring or treatment-resistant acne, isotretinoin is highly effective. It is prescribed under the FDA iPLEDGE program because it causes serious birth defects, so anyone who could become pregnant must use strict contraception and have regular pregnancy tests. Report any low mood on any acne treatment to your doctor right away.

Psoriasis, eczema and beyond

Common first treatments for psoriasis are topical steroids and vitamin D analogues, used alongside generous moisturizers. When creams are not enough, a dermatologist may offer light therapy (phototherapy) delivered in a clinic, tablets that act on the immune system, or injectable biologic medicines. Newer prescription creams and injectable treatments are also available for moderate to severe eczema. These options are tailored to the individual, and some require monitoring, so they are managed by a dermatologist.

Skin cancer treatment

Most basal cell and squamous cell cancers, and most early melanomas, are treated by removing them surgically, often in a single short procedure under local anesthetic. Other options for some superficial cancers include freezing, scraping, prescription creams and light-based treatments. More advanced melanoma may need further surgery and medicines that target the cancer or boost the immune response. The earlier a skin cancer is found, the simpler its treatment usually is.

Specific groups

Skin advice changes with age, pregnancy and skin tone. The fundamentals — protect from UV, look after the barrier, get changing spots checked — apply to everyone, but some groups need extra care or different guidance, and some common treatments are unsafe for particular people. If you are in one of the groups below, mention it whenever a new treatment is suggested.

Babies and children

Babies under 6 months should be kept out of direct sun, in shade and lightweight protective clothing; ask your pediatrician before using sunscreen at this age. From 6 months, use shade, clothing, hats and sunscreen. Protecting children carefully matters because sunburn in childhood raises melanoma risk for life. Eczema often starts in infancy, and generous moisturizing is the foundation of care. A new rash with fever, or a rash that does not fade when a glass is pressed against it, needs urgent medical assessment.

Teens

Acne is extremely common in the teenage years, and effective treatment is worth seeking early, especially if it is scarring or affecting confidence. Teens are also the group most drawn to tanning, and indoor tanning raises the risk of skin cancer, including melanoma. Many states restrict indoor tanning for minors. The US Preventive Services Task Force recommends that clinicians counsel young people with fair skin, from 6 months to 24 years, about minimizing UV exposure.

Pregnancy

Isotretinoin must never be taken in pregnancy, and other retinoids, including some topical ones, are generally avoided; tell your obstetric provider about every skin product you use. Pregnancy can darken patches of facial skin, which sun protection helps limit. Itching in pregnancy, particularly of the palms and soles and without a rash, needs prompt assessment for intrahepatic cholestasis of pregnancy, a liver condition that requires monitoring.

Older adults

With age, skin becomes thinner, drier and more fragile, so it bruises and tears more easily and heals more slowly. Skin cancer risk also rises with age and cumulative sun exposure. Moisturize daily, protect skin from knocks, and never assume a new or changing spot is "just an age spot." Report skin tears, slow healing or easy bruising, which can reflect medicine effects, including blood thinners and long-term steroids, or an underlying condition.

Darker skin and people with diabetes

In darker skin, redness can be harder to see, so eczema and psoriasis may look purple, gray or dark brown, and inflammation can leave long-lasting dark marks. Skin cancer is less common but is more often diagnosed late, so check palms, soles, nails and the inside of the mouth as well as sun-exposed areas. People with diabetes should check their feet daily and have any foot wound, blister or spreading redness checked the same day, because nerve damage can hide injuries and infections can progress quickly.

Myths and the guidance behind them

Skin care attracts more marketing and folklore than almost any other area of health, and some popular beliefs actively steer people away from what works. These are the myths dermatologists most often have to correct, along with what the guidance actually says. If a product promises results that sound too good to be true, ask your doctor or pharmacist before buying it.

• Myth: A base tan protects you. Guidance: A tan is a sign of UV damage, and indoor tanning raises skin cancer risk.
• Myth: You do not need sunscreen on cloudy or cool days. Guidance: UV passes through clouds; check the UV Index, not the temperature.
• Myth: People with dark skin cannot get skin cancer. Guidance: It is less common but happens, and is more often found late.
• Myth: Acne is caused by dirt or poor hygiene. Guidance: It is not; scrubbing and harsh products make it worse.
• Myth: Steroid creams are dangerous and should be avoided. Guidance: Used at the right strength and amount, they are safe and effective; under-use prolongs flares.
• Myth: Wounds heal best when left open to the air. Guidance: Covered, moist wounds heal better.
• Myth: Expensive anti-aging creams beat the basics. Guidance: Daily sun protection and not smoking do more than any product; retinoids have the best evidence.

Costs, coverage and talking to your doctor

Many skin problems can be handled by your primary care provider, and starting there is often quicker and cheaper than going straight to a dermatologist. Some insurance plans require a referral to see a dermatologist, and waits can be long in some areas, so ask whether a suspicious mole can be prioritized. Treatment for medical skin conditions such as eczema, psoriasis, acne and skin cancer is generally covered by insurance and Medicare, while cosmetic procedures usually are not. Newer prescription treatments can be expensive and may need prior authorization; ask about generic alternatives and manufacturer assistance programs if cost is a barrier.

Effective everyday care is inexpensive. A basic fragrance-free moisturizer, petroleum jelly, a gentle cleanser and a large bottle of broad-spectrum SPF 30 sunscreen cost little, and store brands generally work as well as premium ones. A pharmacist can help you choose over-the-counter products for dry skin, mild acne and athlete's foot, and can tell you when a problem needs a doctor instead.

Before an appointment, write down when the problem started, what it looked like at its worst, what makes it better or worse, and every product and medicine you have tried, including how much and for how long. Photos taken during a flare are useful if the skin looks better on the day. If you are worried about a mole, say so clearly and point it out; do not assume it will be noticed during a general exam.

• Does this spot need a biopsy, and how soon?
• How much of this cream should I use, how often and for how long?
• What should I do if this treatment has not worked by a certain date?
• How often should I have my skin checked, given my risk factors?
• Could any of my medicines be affecting my skin?

A practical 4-week plan

Small, consistent changes do more for your skin than any single product. This plan builds a simple routine over a month, covering washing, moisturizing, sun protection and checking your skin. Adjust it to your own skin and to any advice from your doctor or dermatologist, and stop any product that stings, burns or causes a new rash. The aim is a routine simple enough to keep.

Week 1: Fix the basics

Replace harsh soap and fragranced washes with a gentle, fragrance-free cleanser. Shorten showers to about 5 to 10 minutes in warm water, and moisturize within a few minutes of drying off, every day. Notice which products and habits seem to trigger dryness, itch or breakouts, and write them down so you can spot patterns over the coming weeks. If you have a prescribed cream, use it as directed alongside these changes.

Week 2: Build sun habits

Buy a broad-spectrum, water-resistant SPF 30 or higher sunscreen and a wide-brimmed hat. Check the UV Index each morning and apply sunscreen to your face, neck, ears and hands on any day you will be outside. Keep a small bottle in your bag or car so reapplication is easy, and practice applying a full shot-glass amount before a day outdoors, and add sunglasses that block UV.

Week 3: Do your first full skin check

In good light, check your whole body with a full-length and a hand mirror, and ask someone to check your back. Photograph any mole you are unsure about, with a ruler for scale. Make an appointment for anything new, changing, bleeding or not healing, and set a monthly reminder to repeat the check so that change becomes easy to notice.

Week 4: Review and follow through

Look back at your notes. If a skin condition is not improving despite consistent care, book an appointment and bring your notes and photos. Check that you are using any prescribed treatment in the amount and for the length of time advised. Confirm your tetanus booster is up to date, and keep the new routine going as a habit rather than a project.

Every guide in this topic

• Sun Protection: What the Evidence Actually Says
• The Evidence on Eczema, Without the Hype
• Acne: What Published Guidance Supports
• What the Guidance Really Says About Psoriasis
• What the Guidance Really Says About Skin Cancer Signs
• Dry Skin: Sorting the Evidence From the Noise
• Wound Care: What the Evidence Actually Says
• Fungal Skin Infections: Sorting the Evidence From the Noise
• The Evidence on Skin and Aging, Without the Hype
• Itching: What the Evidence Actually Says

Frequently asked questions

What SPF should I use, and how often should I reapply?

The American Academy of Dermatology recommends a broad-spectrum, water-resistant sunscreen with SPF 30 or higher. Use about 1 ounce, roughly a shot glass, to cover an adult body, apply it before going outside, and reapply every 2 hours and after swimming or sweating. Combine sunscreen with shade, clothing and a wide-brimmed hat rather than relying on it alone.

How can I tell if a mole might be melanoma?

Use the ABCDEs: Asymmetry, irregular Border, more than one Color, Diameter larger than about 6 mm (1/4 inch), and Evolving, meaning any change. Change over weeks or months is the most important sign. A mole that looks different from your others, or that itches, bleeds or crusts, should also be checked by your doctor or a dermatologist promptly.

Is it safe to use steroid creams for eczema?

Yes, when used at the strength, amount and duration your doctor recommends. Topical steroids are matched to the severity of the rash and the body area, with milder ones for the face and skin folds. Under-using them through fear is a common reason flares last longer. Ask your doctor how many fingertip units to apply and when to stop.

Why is my acne treatment not working?

Most acne treatments take 6 to 8 weeks or longer to show results, so it may simply be too soon. Using the product inconsistently, scrubbing or picking, and using pore-clogging makeup or moisturizers can also hold progress back. If acne is scarring, deep and painful, or not improving after a fair trial, see your doctor or a dermatologist about stronger options.

Do I need sunscreen on cloudy days or in winter?

Often, yes. UV passes through clouds, and snow, sand and water reflect it back at you. Temperature is not a guide to UV strength. Check the UV Index, which is published daily and shown in most weather apps; when it is 3 or higher, protect exposed skin with clothing, shade and sunscreen.

What is the best way to care for very dry skin?

Keep showers short and warm rather than hot, switch to a gentle fragrance-free cleanser, and apply moisturizer to damp skin within a few minutes of bathing. Creams and ointments work better than lotions for very dry skin. Use a humidifier in dry weather. If dryness is severe, painful or comes with intense itch, see your doctor.

When is itching a sign of something more serious?

Itching without a visible rash, especially if it is persistent or comes with weight loss, night sweats, tiredness, yellowing skin or swollen glands, can be a sign of liver, kidney or thyroid disease, iron deficiency or lymphoma. See your doctor. In pregnancy, itching of the palms and soles needs prompt assessment. Call 911 for itching with hives and facial swelling or trouble breathing.

How should I treat athlete's foot?

Use an over-the-counter antifungal cream or spray and keep using it for the full time on the label, even after the skin looks clear. Dry carefully between your toes, rotate shoes, and wear shower shoes in shared showers. See your doctor for spreading redness or swelling, and anyone with diabetes should have a foot problem checked promptly.

Should I let a cut air out or keep it covered?

Keep it covered. Rinse the cut under clean running water, then cover it with a clean bandage and a thin layer of petroleum jelly to keep it moist, which helps it heal. Change the bandage when wet or dirty. Check your tetanus status for dirty or deep wounds, and get same-day care for signs of infection.

Are tanning beds safer than the sun?

No. Indoor tanning exposes your skin to concentrated UV and raises the risk of skin cancer, including melanoma, as well as speeding up skin aging. There is no safe level of tanning-bed use, and it is not a safe way to get vitamin D. Get vitamin D from food or, if your doctor recommends it, a supplement.

When to speak to a doctor

See your doctor or a dermatologist promptly about any mole that is new, changing, irregular, multicolored, larger than about 6 mm (1/4 inch), or itching, bleeding or crusting, and any sore or scaly patch that does not heal. See your doctor for persistent itching without a rash, eczema or psoriasis that is not responding to treatment, new joint pain with psoriasis, scarring or cystic acne, or low mood on any acne treatment. Get same-day care for a wound that is deep or gaping, from an animal or human bite, or showing signs of infection; for spreading redness, warmth and swelling; for eczema with fever and painful clustered blisters or punched-out sores; and for any foot problem in someone with diabetes. Call 911 for bleeding that will not stop with firm pressure, widespread redness or pustules with fever, widespread painful blistering, hives with swelling of the face or throat or trouble breathing, or severe sunburn with confusion or fainting. If you have thoughts of harming yourself, call or text 988.

Where this comes from

• American Academy of Dermatology — How to prevent skin cancer
• American Academy of Dermatology — What to look for: ABCDEs of melanoma
• CDC — Sun Safety
• FDA — Sunscreen: How to Help Protect Your Skin from the Sun
• US Preventive Services Task Force — Skin Cancer: Screening
• US Preventive Services Task Force — Skin Cancer Prevention: Behavioral Counseling
• American Cancer Society — Signs and Symptoms of Melanoma Skin Cancer
• National Institute of Arthritis and Musculoskeletal and Skin Diseases — Atopic Dermatitis
• National Institute of Arthritis and Musculoskeletal and Skin Diseases — Psoriasis
• CDC — About Tetanus

How this page was put together

Every figure, recommendation and warning above is taken from the guidance named in Where this comes from. Nothing on this page is inferred, summarized or generalized beyond what those bodies publish: where they give a number, it is their number, and where they are silent, so are we. Pages are rebuilt whenever the underlying record changes. Sign-off by a named clinician, where it has happened, is shown at the top of the page along with the date.

Medical disclaimer

This article is general information, not medical advice. It cannot account for your own history, medication or circumstances. Always speak to your doctor, pharmacist or another qualified health professional before making changes that affect your treatment, and never delay seeking medical advice because of something you have read here. In an emergency, call 911.