Dermatitis triggered by light exposure: Causes, signs, and remedies
Photosensitive dermatitis is a skin condition that arises from an abnormal skin reaction to sunlight, particularly ultraviolet (UV) radiation. This condition can manifest in two main types of reactions: phototoxic and photoallergic.
Common Causes
Phototoxic Reactions
Phototoxic reactions occur when certain substances, often medications or chemicals, absorb UV light and cause direct skin damage. The result is an exaggerated sunburn-like reaction. Common causes of phototoxic reactions include antibiotics such as tetracyclines, nonsteroidal anti-inflammatory drugs (NSAIDs), thiazide diuretics, isotretinoin, topical agents like some plants causing phytophotodermatitis, and more.
Photoallergic Reactions
Photoallergic reactions are immune-mediated and develop when UV exposure changes a chemical on the skin, triggering an allergic response. These reactions are less common but can be triggered by substances such as sunscreens with certain ingredients, fragrances, topical medications like topical corticosteroids, and others.
Both types of reactions lead to skin inflammation, manifesting as rash, redness, blistering, or eczema-like lesions after sun exposure.
Treatments
The treatment of photosensitive dermatitis generally follows these principles:
- Avoidance of UV exposure: Staying out of direct sunlight, especially during peak UV hours, and minimizing exposure to the triggering substances is the first-line approach.
- Sun protection: Using broad-spectrum sunscreen with high SPF that blocks both UVA and UVB rays, protective clothing, hats, and sunglasses is essential.
- Medications: Topical corticosteroids are commonly used to reduce inflammation and symptoms in both phototoxic and photoallergic dermatitis. Antihistamines may be prescribed to alleviate itching. In severe cases or if secondary infection occurs, systemic treatments or antibiotics might be necessary.
- Additional measures: Cooling compresses for symptomatic relief, moisturizing with aloe vera or soy-based lotions, and avoiding further skin trauma such as popping blisters are also recommended.
Summary Table
| Aspect | Phototoxic Reaction | Photoallergic Reaction | |---------------------------|-----------------------------|-------------------------------------| | Mechanism | Direct UV-induced skin damage with sensitizing chemical | Immune-mediated allergic response triggered by UV-modified chemical | | Common triggers | Antibiotics, NSAIDs, thiazides, isotretinoin, plants | Sunscreens, fragrances, topical corticosteroids | | Onset | Minutes to hours after exposure | 24-72 hours after exposure | | Clinical features | Sunburn-like redness, blistering | Eczema-like rash, itching, spreading beyond exposed areas | | Treatment | Avoid UV + corticosteroids + symptomatic care | Avoid UV + corticosteroids + possible antihistamines |
In summary, photosensitive dermatitis is caused by UV-triggered skin reactions often related to medications or topical agents. Treatment centers on sun avoidance, protective measures, and topical steroids to control inflammation.
If symptoms are severe or fail to improve with these treatments, consulting a dermatologist for further evaluation and management is recommended. It's also important to note that there may be potential associations between phototoxic drugs and an increased skin cancer risk, and that photosensitive dermatitis may also negatively impact a person's lifestyle, including employment status.
Additionally, older adults may be at a higher risk for developing photosensitivity reactions, as more than one-fifth of their medications are potentially phototoxic, photoallergic, or both. People with skin rashes who develop weakness, headaches, a fever with chills, and flu-like symptoms after sun exposure should see a doctor.
[1] British Association of Dermatologists. (2020). Photosensitivity. [online] Available at: https://www.bad.org.uk/for-the-public/skin-conditions/photosensitivity [Accessed 15 Mar. 2023].
[2] American Academy of Dermatology. (2021). Photosensitivity. [online] Available at: https://www.aad.org/public/diseases/skin-conditions/photosensitivity [Accessed 15 Mar. 2023].
[3] National Health Service. (2021). Photosensitivity. [online] Available at: https://www.nhs.uk/conditions/photosensitivity/ [Accessed 15 Mar. 2023].
[4] Mayo Clinic. (2021). Photosensitivity. [online] Available at: https://www.mayoclinic.org/diseases-conditions/photosensitivity/symptoms-causes/syc-20378078 [Accessed 15 Mar. 2023].
[5] Skin Cancer Foundation. (2021). Photosensitivity. [online] Available at: https://www.skincancer.org/prevention/sun-protection/photosensitivity [Accessed 15 Mar. 2023].
- The management of photosensitive dermatitis involves the use of broad-spectrum sunscreens with high SPF, which are essential for protecting the skin from UV radiation, a key factor in triggering photosensitive reactions.
- In addition to other causes of photosensitive dermatitis, some medical-conditions such as skin diseases requiring the use of topical corticosteroids may contribute to an increased risk of photoallergic reactions due to these substances potentially being potential triggers.
