Merck Manual

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Julia Benedetti

, MD, Harvard Medical School

Reviewed/Revised Oct 2023 | Modified Nov 2023
Topic Resources

Sunburn results from a brief (acute) overexposure to ultraviolet (UV) light.

  • Overexposure to ultraviolet light causes sunburn.

  • Sunburn causes painful reddened skin and sometimes blisters, fever, and chills.

  • People can prevent sunburn by avoiding excessive sun exposure and by using sunscreens.

  • Cold-water compresses, moisturizers, and nonsteroidal anti-inflammatory drugs ease pain until the sunburn heals.

The amount of sun exposure required to produce a sunburn varies with the amount of melanin in the skin (usually visible as the amount of pigmentation), the ability to produce more melanin, and the amount of UV light in the sunlight on the day of overexposure.

Sunburn results in painful reddened skin. Severe sunburn may cause swelling and blisters. Symptoms may begin as soon as 1 hour after exposure and typically reach their peak within 3 days (usually between 12 hours and 24 hours). Some severely sunburned people develop a fever, chills, and weakness and on rare occasions even may go into shock Shock Shock is a life-threatening condition in which blood flow to the organs is low, decreasing delivery of oxygen and thus causing organ damage and sometimes death. Blood pressure is usually low... read more (characterized by very low blood pressure, fainting, and profound weakness).

Several days after a sunburn, people with naturally fair skin may have peeling in the burned area, usually accompanied by itching. These peeled areas are even more sensitive to sunburn for several weeks. Sunburned skin, particularly peeled sunburned skin, can become infected. Permanent brown spots called lentigines may develop. People who have had severe sunburns when young are at greater risk of skin cancer, particularly melanoma Melanoma Melanoma is a skin cancer that begins in the pigment-producing cells of the skin (melanocytes). Melanomas can begin on normal skin or in existing moles. They may be irregular, flat or raised... read more Melanoma , in later years, even if they have not been exposed to much sun since that time.

Did You Know...

  • People can get sunburned even on cloudy days because light clouds do not filter ultraviolet light.

  • Even sunscreens that are water-resistant need to be reapplied after swimming or sweating.

Treatment of Sunburn

  • Cold compresses and other soothing, cooling skin applications

  • Nonsteroidal anti-inflammatory drugs (NSAIDs)

  • Sometimes antibiotic burn creams

Cold-water compresses can soothe raw, hot areas, as can aloe vera and over-the-counter skin moisturizers; products without anesthetics or perfumes (which might irritate or sensitize the skin, causing allergic reactions) are recommended. NSAIDs taken by mouth help relieve pain and inflammation. Petrolatum-based products such as petroleum jelly should be avoided in severe sunburns. Corticosteroids applied to the skin seem to be no more effective than cool compresses.

Ointments or lotions containing anesthetics (such as benzocaine and diphenhydramine) temporarily relieve pain but should be avoided because they occasionally trigger an allergic reaction.

Specific antibiotic burn creams are required only for severe blistering. Most sunburn blisters break on their own and do not need to be popped and drained. Sunburned skin rarely becomes infected, but if an infection develops, healing may be delayed. A doctor can determine the severity of an infection and prescribe antibiotics if necessary.

Sunburned skin begins healing by itself within several days, but complete healing may take weeks. After burned skin peels, the newly exposed layers are thin and initially very sensitive to sunlight and must be protected for several weeks.

Prevention of Sunburn

  • Avoid overexposure to sun

  • Wear protective clothing

  • Use sunscreens


The best—and most obvious—way to prevent sun damage is to stay out of strong, direct sunlight. Exposure to bright midday sun should be avoided, even for people with dark skin. UV rays are not as strong before 10 AM and after 4 PM. If sun exposure is unavoidable, the person should seek shade as soon as possible, cover up in UV-protective clothing, and wear sunscreen, a broad-brimmed hat, and UV-protective sunglasses.

Many materials are capable of filtering or blocking UV radiation, but many are not. Clothing, ordinary window glass, smoke, and smog filter out many of the damaging rays. However, water is not a good filter. UVA and UVB light can penetrate a foot (about 30 centimeters) of clear water. Clouds and fog are also not good filters of UV light—a person can get sunburned on a cloudy or foggy day.

Snow, water, and sand reflect sunlight, magnifying the amount of UV light that reaches the skin. People also burn more quickly at high altitudes, where the thin air allows more burning UV light to reach the skin, and low latitudes (such as at the equator).

Although sun exposure helps generate vitamin D, many experts recommend maintaining adequate vitamin D levels by consuming supplements if needed rather than by intentional overexposure to sunlight (5 to 15 minutes of sun exposure on the arms a few days a week is probably enough to maintain vitamin D levels).


The sun's damaging effects can be further minimized by wearing protective coverings such as hats, shirts, pants, and sunglasses. Fabrics with a tight weave block the sun better than fabrics with a loose weave. Special clothing that provides high sun protection is commercially available. This type of clothing is labeled with ultraviolet protection factor (UPF) followed by a number that indicates the level of protection (similar to sunscreen labeling). Broad-brimmed hats help protect the face, ears, and neck, but people still need to apply sunscreen to these areas. People should regularly wear UV-protective, wrap-around sunglasses to help shield the eyes and eyelids.


Before exposure to strong direct sunlight, a person should apply a sunscreen, which is a cream or lotion containing chemicals that protect the skin by filtering out UV light. Older sunscreens tended to filter only UVB light, but most newer sunscreens effectively filter UVA light as well.

Sunscreens are available in a wide variety of formulations, including creams, lotions, gels, foams, sprays, powders, and sticks. Self-tanning products do not provide significant protection from UV exposure.

Chemical sunscreens contain several substances that absorb UV radiation. Ingredients that absorb UVB radiation include cinnamates, salicylates, and para-aminobenzoic acid (PABA) derivatives. Benzophenones block UVA and UVB light. Avobenzone and ecamsule filter in the UVA range and may be added to provide further UVA protection.

Barrier or mineral sunscreens contain the substances zinc oxide or titanium dioxide, which reflect both UVB and UVA rays (thus blocking them from reaching the skin). These once thick, white ointments have been reformulated to create a more transparent layer while still blocking almost all sunlight from the skin. These newer sunscreens have a more pleasing thickness and color, which allow them to be combined with other traditional chemical blockers, thereby providing even more sun protection to a given formulation. Some cosmetics also contain zinc oxide or titanium dioxide.

All chemical sunscreen ingredients are thought to be absorbed by the body to some degree. Although most ingredients cause minimal side effects, some do have potential risks, and others are currently being studied. Traditional barrier sunscreens have relatively large mineral particles that are not absorbed by the body and are currently considered safe. Newer formulations of mineral sunscreens are made with extremely small particles (nanoparticles) that may be absorbed by the body. Although these nanoparticles are thought to be safe, they are still being studied. People concerned about the effects of absorbed nanoparticles may prefer to use so-called "non-nano" mineral sunscreens.

In the United States, the Food and Drug Administration (FDA) rates sunscreens by their sun protection factor (SPF) number—the higher the SPF number, the greater the protection. Sunscreens rated between 2 and 14 provide minimal protection, those rated between 15 and 29 provide good protection, and those rated 30 and above provide maximum protection. Products that protect against sunburn and photoaging, and also reduce the risk of skin cancer, are labeled broad spectrum and have an SPF of 15 (or higher). The SPF, however, only quantifies the protection against UVB light exposure. There is no scale for UVA light protection.

For the best protection, people should use a broad-spectrum, water-resistant sunscreen with an SPF rating of 30 or higher. One ounce (about 30 milliliters) should be used to cover the entire body surface of an average-sized person.

Sunscreens can fail if not enough of the product is applied, if the product is applied too late (sunscreens should optimally be applied 30 minutes before exposure to the sun), and if the product is not reapplied after swimming or sweating (even sunscreens labeled as water-resistant) or every 2 hours during sun exposure. Most people apply less than half the recommended amount of sunscreen.

Did You Know...

  • An ounce of sunscreen (about 30 milliliters or enough to fill a standard shot glass) is usually needed to cover the entire body. Most people apply less than half that.

Sometimes sunscreens cause allergic reactions. People may react to the sunscreen after applying it or after applying it and then going in the sun (called a photoallergic reaction Chemical photosensitivity Chemical photosensitivity ). Some dermatologists can do tests to diagnose such photosensitivity reactions Photosensitivity Reactions Photosensitivity, sometimes referred to as a sun allergy, is an immune system reaction that is triggered by sunlight. Sunlight can trigger immune system reactions. People develop itchy eruptions... read more Photosensitivity Reactions if the reason for the reaction is unclear.

Are Tans Healthy?

In a word—no. Although a suntan is often considered an emblem of good health and of an active, athletic life, tanning for its own sake has no health benefit and is actually a health hazard. Any exposure to ultraviolet A or B (UVA or UVB) light can alter or damage the skin. Long-term exposure to natural sunlight causes skin damage and increases the risk of skin cancer. Exposure to the artificial sunlight used in tanning salons is harmful as well. The UVA lights used in these establishments cause the same long-term effects as exposure to UVB light, such as wrinkling and mottled pigmentation (photoaging) and skin cancer. Quite simply, there is no safe tan.

Self-tanning, or sunless, lotions do not really tan the skin but, rather, stain it. They therefore provide a safe way to achieve a tanned look without risking dangerous exposure to ultraviolet rays. However, because they do not increase melanin production, self-tanning lotions do not offer protection from the sun. Therefore, sunscreens should still be used during exposure to sunlight. Results with the use of self-tanning lotions may vary, depending on a person’s skin type, the formulation used, and the manner in which the lotion is applied.


Polypodium leucotomos (a natural tropical fern extract) and nicotinamide (a form of vitamin B3) are supplements that are taken by mouth that provide some protection against the damaging effects of sunlight. However, they are not a replacement for other methods of sun protection.

Drugs Mentioned In This Article

Generic Name Select Brand Names
Advocate Pain Relief Stick, Americaine, Anbesol, Anbesol Baby , Anbesol Jr , Banadyne-3, Benzodent, Benz-O-Sthetic, Boil-Ease, Cepacol Sensations, Chloraseptic, Comfort Caine , Dry Socket Remedy, Freez Eez, HURRICAINE, HURRICAINE ONE, Little Remedies for Teethers, Monistat Care, Orabase, OraCoat CankerMelts, Orajel, Orajel Baby, Orajel Denture Plus, Orajel Maximum Strength, Orajel P.M., Orajel Protective, Orajel Severe Pain, Orajel Swabs, Orajel Ultra, Oral Pain Relief , Oticaine , Otocain, Outgro, Pinnacaine, Pro-Caine, RE Benzotic, Topex, Topicale Xtra, Zilactin-B
Aid to Sleep, Alka-Seltzer Plus Allergy, Aller-G-Time , Altaryl, Banophen , Benadryl, Benadryl Allergy, Benadryl Allergy Children's , Benadryl Allergy Dye Free, Benadryl Allergy Kapgel, Benadryl Allergy Quick Dissolve, Benadryl Allergy Ultratab, Benadryl Children's Allergy, Benadryl Children's Allergy Fastmelt, Benadryl Children's Perfect Measure, Benadryl Itch Stopping, Ben-Tann , Children's Allergy, Compoz Nighttime Sleep Aid, Diphedryl , DIPHEN, Diphen AF , Diphenhist, DiphenMax , Dytan, ElixSure Allergy, Genahist , Geri-Dryl, Hydramine, Itch Relief , M-Dryl, Nighttime Sleep Aid, Nytol, PediaCare Children's Allergy, PediaCare Nighttime Cough, PediaClear Children's Cough, PHARBEDRYL, Q-Dryl, Quenalin , Siladryl Allergy, Silphen , Simply Sleep , Sleep Tabs, Sleepinal, Sominex, Sominex Maximum Strength, Theraflu Multi-Symptom Strip, Triaminic Allergy Thin Strip, Triaminic Cough and Runny Nose Strip, Tusstat, Unisom, Uni-Tann, Valu-Dryl , Vanamine PD, Vicks Qlearquil Nighttime Allergy Relief, Vicks ZzzQuil Nightime Sleep-Aid
Aquaphor 3 IN 1 Diaper Rash, Aquaphor Baby Fast Relief Diaper Rash, Aquaphor Fast Relief Diaper Rash, Balmex, Boudreaux Butt Paste, Boudreauxs Rask, Carlesta, Coppertone, COZIMA, Critic-Aid Thick Moisture Barrier Skin, DermacinRx Zinctral, Desitin, Desitin Maximum Strength, Desitin Rapid Relief, Diaper Rash , Dr. Smith Adult Barrier, Dr. Smith's, Dr. Smith's Diaper Rash, Dr. Smith's Rash + Skin, DynaShield, Eucerin Baby Sunscreen Sensitive Mineral , Eucerin Sunscreen Sensitive Mineral, Flanders Buttocks , Medi-Paste, Novana Protect, PanOxyl AM, SECURA, Triple Paste, Triple Paste Adult Incontinence, Triple Paste Rash, Z-Bum
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