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.
- Duration of exposure.
- Height of the sun (greatest exposure at midday, in midsummer 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.
- The skin is hot and red. It blanches on pressure. It is painful and tender and there may be some oedema.
- Erythema usually occurs 2-6 hours after exposure and peaks at 12- 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.
- Assess degree of pain.
- Check for dehydration.
- Look for symptoms/signs of heat exhaustion or heatstroke? For example:
- High body temperature.
- Fatigue, weakness, dizziness, fainting, headache.
- Nausea or vomiting.
- Rapid pulse.
- Altered behaviour - irritability, agitation, impaired judgement, confusion, disorientation, hallucinations.
- In children (as with any burn) consider whether neglect or non-accidental injury could be a cause.
- Presence of co-existing injuries.
- Note co-existing or contributing medical conditions.
- 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.
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.
Who needs referral?
Minor burns, including sunburn, can usually be treated in primary care. Superficial epidermal burns do not need referral. 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.
- All circumferential burns (those that go all the way round a part of the body).
- Superficial dermal burns of more than 3% total burn surface area (TBSA) in those aged ≥16.
- Superficial dermal burns of more than 2% TBSA in under-16s.
- Superficial dermal burns involving the face, hands, feet, perineum, genitalia or flexures.
- Suspicion of dehydration, heatstroke, shock or sepsis.
- Suspicion of non-accidental injury or neglect.
Referral should also be considered in the following scenarios:
- Young or old: children aged <5 years, adults aged >60 years.
- Co-existing 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.
- A wound that has not healed 14 days after injury.
The cause is usually clear from the history, but consider:
- 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]
- 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).
- Treat any dehydration or heatstroke.
- 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. However, one small trial 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; however, study designs or methods were flawed. Furthermore, regardless of the treatment modality, the damage to epidermal cells is the same. Topical anaesthetics are not recommended.
Treatment should be as for any other severe burn. See separate Burns - Assessment and Management article.
- Heatstroke or dehydration.
- Secondary infection of the burn.
- Exacerbation of some dermatological conditions.
- Premature ageing, solar keratoses, basal cell carcinoma, squamous cell carcinoma of skin and malignant melanoma of skin are associated with sun exposure.
- Photosensitivity reactions.
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 ≥15. Use a sunscreen with both UVA and UVB protection. Higher minimum factor sunscreen may be advised outside the UK.
- Use a generous amount of sunscreen. Ideally, apply it half an hour before exposure. Reapply regularly. Reapply after being in water, even if sunscreen claims to be water-resistant.
- A balance must be struck between the benefits of sunshine for vitamin D status and the risk of increasing skin cancer rates.
- It is uncertain whether use of sunscreens prevents skin cancer.
- The safest advice with regard to how much sunscreen to use is "apply liberally". Different products require different amounts so attempts to suggest a standard formula are confusing and not necessarily accurate. The British Association of Dermatologists (BAD) sunscreen fact sheet advises the usual amount is at least six teaspoons to cover the skin of an average adult.
- 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.
- 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.
- The Met Office provides information as the Solar UV Index with their weather forecasts.Basically, the higher the index (from 1 to 10), the greater the risk from the sun and the more skin protection is needed outside.
Potential dietary protective measures have been suggested:
- An oral food supplement containing Polypodium leucotomos may provide additional oral photoprotection and reduce sunburn.
- Dietary supplementation with beta-carotene may be protective.
- A topical antioxidant solution containing stabilised vitamins C and E may offer photoprotection (according to a small trial).
Further reading and references
; National network for Burn Care (NNBC), February 2012
; Public Health England (May 2014)
; Benefits of sunlight: a bright spot for human health. Environ Health Perspect. 2008 Apr116(4):A160-7.
; DermNet NZ
; NICE CKS, May 2013 (UK access only)
; Emergency and early management of burns and scalds. BMJ. 2009 Apr 8338:b1037. doi: 10.1136/bmj.b1037.
; Solar burn reactivation induced by methotrexate. Pharmacotherapy. 2010 Apr30(4):123e-6e.
; Ultraviolet recall reaction after total body irradiation, etoposide, and J Am Acad Dermatol. 2007 Mar56(3):494-9. Epub 2006 Dec 20.
; Topical corticosteroids in the treatment of acute sunburn: a randomized, Arch Dermatol. 2008 May144(5):620-4.
; Management of acute sunburn. Am J Clin Dermatol. 20045(1):39-47.
; NICE Public Health Guideline (January 2011)
; The good, the bad, and the ugly of sunscreens. Clin Pharmacol Ther. 2011 Jan89(1):31-3.
; British Association of Dermatologists (BAD)
; Met Office
; Protection from sunburn with beta-Carotene--a meta-analysis. Photochem Photobiol. 2008 Mar-Apr84(2):284-8. Epub 2007 Dec 15.
; A topical antioxidant solution containing vitamins C and E stabilized by ferulic J Am Acad Dermatol. 2008 Sep59(3):418-25. Epub 2008 Jul 7.
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