Allergic skin diseases are rashes driven by an immune reaction to something the body has met. The main types are allergic contact dermatitis, urticaria (hives) with or without deeper swelling called angioedema, and rashes caused by medicines. Atopic eczema is related and has its own page.
They differ in timing. Hives appear within minutes to hours and each weal fades within a day. Contact allergy appears 1 to 3 days after exposure and lasts weeks. Identifying and avoiding the trigger is the real cure where one exists. When no trigger is found, as in most chronic hives, the condition is controlled with medication until it burns out.
Symptoms
- Raised, itchy weals that move around and fade within 24 hours
- Swelling of lips, eyelids, hands or feet
- Red, itchy, blistering or scaly skin where something touched it
- Rash under jewellery, a watch, jeans stud or on the hands
- Eyelid or face rash from cosmetics, hair dye or nail products
- A widespread red rash starting days after a new medicine
- Dry, cracked, thickened skin from long-standing contact allergy
Causes and risk factors
Common contact allergens are nickel, fragrances, preservatives such as methylisothiazolinone, hair dye (PPD), acrylates in gel nails, rubber chemicals in gloves, adhesives and some plants. Acute hives follow infections, foods (nuts, shellfish, eggs), medicines such as antibiotics and anti-inflammatory painkillers, insect stings and latex. Chronic spontaneous urticaria, lasting over 6 weeks, is usually autoimmune and not caused by an outside allergen. Physical triggers include pressure, cold, heat and scratching. Drug rashes most often follow antibiotics, anti-epileptics and allopurinol.
How it is diagnosed
- History and distribution of the rash: Timing, site, occupation, hobbies, cosmetics and medicines often reveal the cause.
- Patch testing: Allergens are taped to the back for 48 hours and read at 2 and 4 days or later. The reference test for contact allergy, needing three visits in one week.
- Skin prick tests and specific IgE blood tests: For suspected immediate allergy to foods, latex or stings. Of little use in chronic hives.
- Blood tests in chronic urticaria: Blood count, inflammatory markers and thyroid antibodies.
- Skin biopsy: When weals last longer than 24 hours or bruise, or the diagnosis is unclear.
- Supervised drug challenge: In an allergy unit, to confirm or exclude a medicine allergy.
Treatment options
- Avoidance: Once patch testing names the allergen, avoiding it in products and at work clears contact dermatitis.
- Emollients and barrier care: Soap substitutes and frequent moisturising repair irritated skin.
- Topical corticosteroids: Short courses of appropriate strength for contact dermatitis. Tacrolimus ointment for the face and eyelids.
- Non-sedating antihistamines: Cetirizine, loratadine or fexofenadine daily for hives, increased up to fourfold under medical advice.
- Omalizumab: Monthly injections for chronic urticaria not controlled by antihistamines. Ciclosporin is a further option.
- Short oral steroid course: For severe flares only.
- Adrenaline auto-injector: For people who have had anaphylaxis, with a written action plan.
When it is urgent
Call emergency services for swelling of the tongue or throat, difficulty breathing, wheeze, faintness or collapse: this is anaphylaxis. A rash with fever, skin pain, blistering, peeling, or sores in the mouth and eyes after starting a medicine is also an emergency and the drug should be stopped.
Travelling to Türkiye for treatment
Patch testing requires three visits within a week and no sun exposure or steroid on the back beforehand, so it can fit a planned stay. A visit can also provide an allergy work-up and a dermatology opinion on a stubborn rash. Flares, chronic urticaria and omalizumab injections need ongoing care at home, and acute reactions must be treated where you are.
Send your reports, scans and a short history and a Clinic-Y coordinator replies within 24 hours with suitable teams and written, all-inclusive proposals side by side. Reviewing your case is free.
Frequently Asked Questions
What is the difference between allergy and irritation?
Irritant dermatitis comes from repeated damage by water, soap or chemicals and can affect anyone. Allergic dermatitis is a specific immune reaction in sensitised people. Both often coexist on the hands.
Will food allergy tests explain my chronic hives?
Almost never. Hives lasting over 6 weeks are rarely due to food, and broad test panels produce misleading results.
Does contact allergy go away?
Usually it is lifelong, but the skin stays clear if you avoid the allergen.
Can antihistamines be taken long term?
Modern non-sedating ones have a good long-term safety record at standard doses. Higher doses should be supervised.