Photosensitivity

Overview

Photosensitivity describes an exaggerated or abnormal reaction of the skin to sunlight or artificial ultraviolet (UV) light. Instead of the gradual tanning or mild burning most people experience, a photosensitive person may develop a rash, redness, swelling, blistering, or burning sensation after relatively little sun exposure. The reaction usually appears on areas that the sun reaches, such as the face, neck, backs of the hands, and forearms, while skin covered by clothing is spared.

Photosensitivity is not a single disease but a feature shared by several conditions. It can be triggered by medications, applied chemicals, certain plants, underlying medical conditions such as lupus, or inherited tendencies. Identifying and removing the trigger, along with careful sun protection, is the foundation of management.

Reactions can be immediate, appearing within minutes of sun exposure, or delayed by a day or more, which sometimes makes the connection to sunlight harder to recognize. The severity ranges from mild redness to blistering and significant discomfort. Because the causes are so varied, working out what is responsible is an important first step, and a doctor or dermatologist can help identify the trigger and the best way to protect the skin.

Symptoms

Symptoms develop on sun-exposed skin, often within minutes to hours of exposure, though some reactions are delayed by a day or more.

• Redness, like an exaggerated sunburn, on exposed areas
• An itchy or bumpy rash
• Blisters or small fluid-filled spots
• Burning, stinging, or tingling of the skin
• Swelling, especially of the face
• Sharp boundaries where clothing protected the skin

In some people the reaction is mild and short-lived; in others it is severe, recurrent, and disruptive to daily life. Repeated reactions can leave darkened patches or thickened skin over time.

Causes

Photosensitivity occurs through two main mechanisms. In phototoxic reactions, a substance in or on the skin absorbs UV light and directly damages cells, producing an exaggerated sunburn. In photoallergic reactions, UV light changes a substance into one the immune system attacks, producing an itchy, eczema-like rash.

• Medications: Some antibiotics, diuretics, certain anti-inflammatory drugs, retinoids, and others (see drug-induced photosensitivity).
• Topical products: Some fragrances, sunscreens, and skin treatments.
• Plants: Contact with certain plants (such as limes, celery, or wild parsnip) followed by sun exposure.
• Underlying conditions: Lupus, porphyria, and some other disorders.

Risk Factors

• Taking medications known to cause sun sensitivity
• Fair skin that burns easily
• Autoimmune conditions such as lupus
• A family history of light-sensitive skin disorders
• Frequent or intense sun exposure
• Use of certain fragrances or topical products before sun exposure

Diagnosis

A clinician usually identifies photosensitivity from the pattern of the rash on sun-exposed skin and a review of medications, products, and activities. Helpful steps include:

• History: Timing of the rash relative to sun exposure and any new drugs or products.
• Skin examination: Noting the clear cutoff between exposed and covered skin.
• Phototesting: Controlled exposure of small skin areas to measured UV light to confirm sensitivity.
• Photopatch testing: Applying suspected substances and then UV light to identify photoallergens.
• Blood tests: When an underlying condition such as lupus or porphyria is suspected.

Treatment

Treatment centers on removing the trigger and protecting the skin while it heals.

• Stopping the trigger: Where a drug or product is responsible, a clinician may switch or discontinue it. Never stop a prescribed medicine without medical advice.
• Soothing the skin: Cool compresses, moisturizers, and topical corticosteroids can ease an active reaction.
• Oral medication: Antihistamines for itch, and short courses of oral corticosteroids for severe flares.
• Treating underlying disease: Managing conditions such as lupus reduces light sensitivity.

For chronic or recurrent photosensitivity, a dermatologist may recommend supervised light therapy to gradually build tolerance, or other specialist treatments.

Prevention

• Use broad-spectrum sunscreen and reapply regularly when outdoors
• Wear protective clothing, a wide-brimmed hat, and UV-blocking sunglasses
• Seek shade and avoid the midday sun when UV is strongest
• Review your medicines with a pharmacist or doctor for sun-sensitizing effects
• Wash off fragrances or plant juices before going into the sun

When to See a Doctor

See a doctor if you develop an unexplained rash on sun-exposed skin, if reactions are severe or recurrent, or if you suspect a medication is to blame. Seek prompt medical care if you have:

• Widespread blistering or peeling of the skin
• Fever, joint pain, or feeling generally unwell with the rash
• Swelling of the face or signs of an allergic reaction
• A reaction that does not improve with sun avoidance and basic care

Related Topics

Frequently Asked Questions

References

1. American Academy of Dermatology (AAD). Sun sensitivity and skin reactions.
2. MedlinePlus, U.S. National Library of Medicine. Photosensitivity.
3. DermNet. Photosensitivity.
4. Centers for Disease Control and Prevention (CDC). Sun safety.