Photosensitivity (Light Sensitivity)

📌 Definition:

Photosensitivity is a condition in which the skin reacts abnormally to ultraviolet (UV) light from the sun or artificial sources. It may result in rash, redness, itching, burning, or blistering after sun exposure.

🧬 Etymology (Origin of the term):

• "Photo" – from Greek phōs, meaning "light"

• "Sensitivity" – the ability to respond to a stimulus

In medicine, this term describes an abnormal skin reaction to light, often caused by internal or external triggers.

🧠 Main Types:

1. Phototoxic Reaction – A direct skin reaction caused when a chemical (often a drug) becomes toxic after being exposed to UV light.

2. Photoallergic Reaction – An immune response where sunlight and a substance on or in the body combine to trigger an allergic-like reaction.

⚠️ Causes:

💊 Medications:

• Antibiotics (e.g., tetracyclines, sulfonamides)

• Diuretics (e.g., furosemide)

• Retinoids (used for acne)

• Antidepressants

• NSAIDs (e.g., ibuprofen)

🌿 Plants and Foods:

• Lemons, celery, parsley, figs (contain furocoumarins)

🧴 Cosmetic Products:

• Perfumes

• Essential oils

• Some sunscreens and anti-aging creams

🧬 Medical Conditions:

• Systemic Lupus Erythematosus (SLE)

• Porphyria

• Dermatomyositis

• Albinism

🔍 Symptoms:

• Redness, itching, or burning after sun exposure

• Rash or hives

• Blisters or peeling

• Swelling or dryness

• Hyperpigmentation or hypopigmentation (dark or light spots)

🧪 Diagnosis:

• Dermatological examination

• Phototesting – controlled UV exposure test

• Blood tests (to detect autoimmune diseases)

• Photopatch test (to identify allergic triggers with UV light)

💊 Treatment:

🛡️ Prevention:

• Avoid direct sunlight between 10:00 AM and 4:00 PM

• Use broad-spectrum sunscreen (SPF 30 or higher) daily

• Wear protective clothing, hats, and UV-blocking sunglasses

• Read medication labels for photosensitivity warnings

• Keep the skin moisturized and stay hydrated