Causes of skin allergy

Skin allergy happens when the skin reacts to a substance it touches, eats, breathes or is injected with, or when the skin barrier is weak and easily irritated. Finding the trigger is the key to treatment.

Common contact triggers

• Metals such as nickel in jewellery, buckles, watches and mobile phone cases.
• Cosmetics, perfumes, hair dye (para-phenylenediamine), nail products and fragranced soaps.
• Detergents, cleaning products and solvents.
• Rubber and latex, such as gloves and elastic.
• Plants such as poison ivy equivalents, parthenium and some garden plants.
• Topical medicines, including neomycin and some herbal or "ayurvedic" creams.
• Sunscreens and sunlight in photoallergic reactions.

Triggers for hives and swelling

• Foods such as nuts, shellfish, eggs, milk and some fruits.
• Medicines such as penicillin, sulfa drugs, aspirin and other painkillers.
• Insect stings and bites.
• Infections, heat, cold, pressure, sweating and stress.

Triggers for eczema (atopic dermatitis)

• Family history of eczema, asthma or hay fever and a weak skin barrier.
• Dry skin, harsh soaps, hot water and wool or rough fabrics.
• Dust mites, pet dander, pollen and mould.
• Stress, sweat and sudden temperature change.

Factors that raise the risk Wet work, frequent hand washing, a history of allergy, young age, and skin damaged by scratching or other skin disease.

Ayurvedic view (interpretive) Ayurveda links such conditions with aggravated Pitta and Kapha, and incompatible food (viruddha ahara). This is a traditional framework and not a proven cause.

When to see a doctor See a doctor if the rash is widespread, keeps returning, affects your face or eyes, or if the cause is unclear. Patch testing by a skin specialist can find contact allergens.

Remember A rash that appears hours to days after contact with a new product often points to contact allergy.