Sunburn

oPatientPlus articles are written by UK doctors and are based on research evidence, UK and European Guidelines. They are designed for health professionals to use, so you may find the language more technical than the condition leaflets.

See separate related article Burns - Assessment and Management.

Sunburn is a common, acute inflammatory response of skin to exposure to ultraviolet radiation (UVR).

UVR causes vasodilation and release of mast cell mediators, leading to an inflammatory response. Less intense or shorter-duration exposure to UVR leads to increased skin pigmentation (tanning) which provides some protection against further UVR-induced damage.[1]

  • Duration of exposure.
  • Height of the sun (greatest exposure at midday, in mid-summer and at the equator).
  • Type of UVR: UVB is more potent than UVA, but less prevalent in sunlight.
  • Increasing altitude (less atmospheric filtration).
  • Environmental reflection, eg rippling sea, white sand. Snow and ice can facilitate sunburn with ambient temperatures below zero.
  • Lack of protective sunscreen or clothing increases the risk. It is possible to burn through light clothing.
  • Lighter skin pigmentation is a factor, whether congenital or acquired. Being suntanned gives protection. Skin type is graded I to VI according to risk of burning.
  • Moist skin increases the risk.
  • Limb skin is relatively more resistant than that of the face, neck and torso. Areas not habitually exposed are more vulnerable.
  • The filtering effect of the atmosphere has an effect. The diminishing ozone layer increases the risk whilst atmospheric pollution reduces it.
  • Areas of vitiligo are susceptible to burning, as are areas of alopecia. People with albinism are very sensitive to sunburn.
  • Photosensitivity - for example, systemic lupus erythematosus, porphyria; drugs such as tetracyclines and many others. Xeroderma pigmentosum and certain other genetic conditions may cause sunburn with minimal sun exposure, due to defective DNA repair.
  • Overuse of sunlamps.

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  • The skin is hot and red. It blanches on pressure. It is painful and tender and there may be some oedema.
  • Erythema usually occurs 3-4 hours after exposure, and peaks at 24 hours. It resolves over 4-7 days, usually with skin scaling and peeling.
  • With more severe sunburn, vesicles and bullae may form.
  • Systemic symptoms can accompany severe sunburn: there may be headache, chills, malaise, nausea and vomiting.

As for any burn - assess the severity and area covered (see box below). Examine the skin for colour change, blisters and capillary refill:

  • Is the burn painful?
  • Is there any dehydration?
  • Are there symptoms/signs of heat exhaustion or heat stroke? For example:
    • High body temperature.
    • Fatigue, weakness, dizziness, fainting, headache.
    • Nausea or vomiting.
    • Rapid pulse.
    • Myalgia.
    • Altered behaviour - irritability, agitation, impaired judgement, confusion, disorientation, hallucinations.
Burns are categorised as:[2][3]
  • Superficial epidermal: red and painful, but not blistered.
  • Partial thickness (superficial dermal): pale pink and painful with blistering.
  • Partial thickness (deep dermal): dry or moist, blotchy and red, and may be painful or painless. There may be blisters. Capillary refill is absent.
  • Full thickness: dry and white, brown, or black in colour, with no blisters, no pain and no capillary refill.
Sunburn is usually a superficial epidermal burn, but may be partial thickness in severe cases.

The percentage of area burned can be estimated using the 'rule of 9s' (in adults), or by the hand area being 1% of body surface area. Areas of simple erythema are not counted:
  • The adult body is divided into anatomical regions that represent 9%, or multiples of 9%, of the total body surface. Therefore, 9% each for the head and each upper limb. 18% each for each lower limb, front of trunk and back of trunk.
  • The palmar surface of the patient's hand, including the fingers, represents approximately 1% of the patient's body surface.
  • Body surface area differs considerably for children - the Lund and Browder chart takes into account changes in body surface area with age and growth.[3]

Minor burns, including sunburn, can usually be treated in primary care. The following patients need referral (usually to A&E in the first instance, but may be referred to a burns unit, depending on local protocols):

  • All deep dermal and full-thickness burns.
  • Extent of the burn - for burns that are superficial dermal or deeper, refer if the total burn surface area is >10% of body surface in adults aged over 16 years, or >5% of body surface in children aged under 16 years. (Areas of simple erythema only are not counted for this purpose.)
  • Superficial dermal burns involving the face, hands, feet, perineum, genitalia, flexure, or circumferential burns of the limbs, torso, or neck.
  • Dehydration or heat stroke.

Referral is usually appropriate in the following scenarios:

  • Young or old: children aged <5 years, adults aged >60 years.
  • Coexisting medical problems (eg cardiac, respiratory, or hepatic disease; diabetes; immunosuppressed; pregnancy).
  • Needing admission for social reasons, pain control, or if dressings are difficult to manage.
  • Uncertainty about the depth or severity of the burn.
  • Other injuries.
  • Consider non-acute referral to a plastic surgery unit for any wound that has not healed 14 days after injury.

The cause is usually clear from the history, but consider:

  • Photosensitivity.
  • Xeroderma pigmentosum and related conditions (if there is sunburn with minimal exposure).
  • Other types of burn.
  • Neglect or non-accidental injury in children.
  • Solar burn reactivation: this is a rare and idiosyncratic drug reaction, reported with a variety of drugs including methotrexate. It affects areas of the body that have been previously sunburned.[4][5]

Mild-to-moderate sunburn

  • The vast majority of sunburn is superficial and spontaneously resolves.
  • Maintain adequate hydration.
  • Symptoms may be relieved by:
    • A cool shower, or cool compresses.
    • Simple analgesics (paracetamol or ibuprofen).
    • Emollients.
    • Topical diclofenac sodium, which has been shown to reduce pain and erythema (in studies by the manufacturer).[6]

Moderate

  • Treat any dehydration or heat stroke.
  • Symptom relief (as above).
  • If there are blisters (superficial dermal burn), wound care and dressings are needed (see separate Burns - Assessment and Management article).

Some sources suggest that oral non-steroidal anti-inflammatory drugs (NSAIDs) and/or topical steroids reduce erythema.[7][8] However, one small trial[9] and reviews of the literature have been less enthusiastic. One review found that the overall opinion was that corticosteroids, NSAIDs, antioxidants, antihistamines or emollients were ineffective at decreasing recovery time. The remaining studies showed mild improvement with such treatments, but study designs or methods were flawed. Furthermore, regardless of the treatment modality, the damage to epidermal cells is the same.[10] Topical anaesthetics are not recommended.

Severe

Treatment should be as for any other severe burn. (see Burns - Assessment and Management record).

Sunburn is better prevented than treated. Sun protection is the best defence against sunburn and other damaging effects of UVR:

  • Avoid sun exposure, especially between 11 am to 3 pm.
  • Wear protective clothing, including wide-brimmed hats.
  • Apply adequate amounts of sunscreen with a sun protection factor (SPF) of ≥30. Use a sunscreen with both UVA and UVB protection.
  • Use a generous amount of sunscreen. Ideally, apply it half an hour before exposure. Reapply regularly.

Note that:

  • A balance must be struck between the benefits of sunshine for vitamin D status and the risk of increasing skin cancer rates.[13]
  • It is uncertain whether use of sunscreens prevents skin cancer.[14]
  • Correct use of appropriate factor sunscreens or barrier creams should be advised (zinc oxide, titanium dioxide).[15] The correct dose can be calculated using the Surface Area Calculator.[16]
  • The SPF protection offered by a sunscreen indicates how many times longer a user can stay in the sun compared with the individual without the sunscreen - eg a cream with SPF 15 can stay 15 times longer. This is calculated with an application thickness of 2 mg/cm2. Unfortunately, consumers apply much less than this, typically between 0.5 to 1 mg/cm2, giving a sunscreen labelled SPF of 15 a true SPF of 2-4. To cover all sun-exposed areas adequately, the average adult wearing a bathing suit would need to use about 1 oz of sunscreen.[12]
  • The degree of protection against UVA is hard to quantify and is usually much less than protection against UVB.
  • Concomitant use of insect repellents that contain N,N-diethyl-3-methylbenzamide (DEET) also decreases SPF.
  • Water-resistant sun protection lotions last longer than others, but even they get washed off by sweat and swimming and need to be replaced.

Other potential protective measures:

  • An oral food supplement containing Polypodium leucotomos may provide additional oral photoprotection and reduce sunburn.[8]
  • Dietary supplementation with beta-carotene may be protective.[17]
  • A topical antioxidant solution containing stabilised vitamins C and E may offer photoprotection (according to a small trial).[18]

Further reading & references

  1. McStay CM et al, Sunburn, Medscape, May 2010
  2. Burns and Scalds, Clinical Knowledge Summaries (2007)
  3. Enoch S, Roshan A, Shah M; Emergency and early management of burns and scalds. BMJ. 2009 Apr 8;338:b1037. doi: 10.1136/bmj.b1037.
  4. DeVore KJ; Solar burn reactivation induced by methotrexate. Pharmacotherapy. 2010 Apr;30(4):123e-6e.
  5. Goldfeder KL, Levin JM, Katz KA, et al; Ultraviolet recall reaction after total body irradiation, etoposide, and J Am Acad Dermatol. 2007 Mar;56(3):494-9. Epub 2006 Dec 20.
  6. Kienzler JL, Magnette J, Queille-Roussel C, et al; Diclofenac-Na gel is effective in reducing the pain and inflammation associated with exposure to ultraviolet light - results of two clinical studies. Skin Pharmacol Physiol. 2005 May-Jun;18(3):144-52.
  7. Hughes GS, Francom SF, Means LK, et al; Synergistic effects of oral nonsteroidal drugs and topical corticosteroids in the therapy of sunburn in humans. Dermatology. 1992;184(1):54-8.
  8. Sunburn, DermNet NZ, Aug 2010
  9. Faurschou A, Wulf HC; Topical corticosteroids in the treatment of acute sunburn: a randomized, Arch Dermatol. 2008 May;144(5):620-4.
  10. Han A, Maibach HI; Management of acute sunburn. Am J Clin Dermatol. 2004;5(1):39-47.
  11. Diffey B; Has the sun protection factor had its day? BMJ. 2000 Jan 15;320(7228):176-7.
  12. Prevention and treatment of sunburn, The Medical Letter (June 2004)
  13. Skin cancer prevention: information, resources and environmental changes; NICE Public Health Guideline (January 2011)
  14. Berwick M; The good, the bad, and the ugly of sunscreens. Clin Pharmacol Ther. 2011 Jan;89(1):31-3.
  15. Pinnell SR, Fairhurst D, Gillies R, et al; Microfine zinc oxide is a superior sunscreen ingredient to microfine titanium dioxide. Dermatol Surg. 2000 Apr;26(4):309-14.
  16. Halls BSA web calculator; (more extensive calculator which can use other equations)
  17. Kopcke W, Krutmann J; Protection from sunburn with beta-Carotene--a meta-analysis. Photochem Photobiol. 2008 Mar-Apr;84(2):284-8. Epub 2007 Dec 15.
  18. Murray JC, Burch JA, Streilein RD, et al; A topical antioxidant solution containing vitamins C and E stabilized by ferulic J Am Acad Dermatol. 2008 Sep;59(3):418-25. Epub 2008 Jul 7.

Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. EMIS has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.

Original Author:
Dr Laurence Knott, Dr Huw Thomas
Current Version:
Document ID:
2820 (v21)
Last Checked:
18/03/2011
Next Review:
16/03/2016