Redness and itching appear exactly where the skin has touched something external. This is what contact dermatitis usually looks like: a skin reaction to an irritant or allergen, not to something inside the body. Below is what is known about its types, causes, and symptoms, so you can calmly orient yourself before a doctor's visit.
What contact dermatitis is and what types it has
Contact dermatitis is a local inflammatory lesion of the skin that occurs after direct contact with a substance. There are two main types: irritant and allergic. Phototoxic, or photocontact, dermatitis is described separately: a reaction in which an allergen or irritant is activated by sunlight.
Allergic and irritant dermatitis: what the difference is
Irritant dermatitis is the most common type. It is not an allergy but a skin reaction to irritating substances or friction: alkalis such as soap and detergents, solvents, cement, hair dyes, prolonged contact with wet diapers. Very aggressive chemicals cause a reaction after brief contact, while milder ones do so after repeated contact. People with atopic dermatitis have a higher risk of irritant dermatitis.
Allergic contact dermatitis is less common. There is no reaction on first contact: the immune system "gets to know" the substance and responds only to subsequent contacts. Sometimes a substance is tolerated for years before an allergy develops, but once it arises, it persists for life. Typical allergens are nickel and other metals in jewelry and watches, fragrances in perfumes and cosmetics, preservatives in creams, formaldehyde, and latex. In some people, raw, unprocessed fruits and vegetables cause a reaction.
Symptoms of contact dermatitis on the face, legs, and fingers
The skin becomes itchy, dry, and cracked, and blisters may appear. On light skin, the areas turn red; on dark skin, they become dark brown, purple, or gray. The reaction usually occurs several hours or days after contact; in the allergic form, the rash often appears only after 24–48 hours and may persist for weeks. The lesion may be red, streaked, or patchy. The irritant form often looks like dry, red, rough skin, cracks form on the hands, and in addition to itching there may be burning or pain.
Contact dermatitis on the face is associated with cosmetics, hair products, and perfumes—they cause reactions on the face, head, and neck. Contact dermatitis on the fingers and hands is generally the most common location: soap, detergents, solvents, and jewelry metals get there. Contact dermatitis on the legs is often associated with footwear, rubber, or latex, and also with varicose eczema—though it has a different cause, impaired blood flow in the veins of the legs.
Contact dermatitis in children
In children, prolonged contact with wet diapers is specifically noted among irritants. Atopic eczema is also distinguished separately—the most common type of eczema, often hereditary and associated with asthma and hay fever.
Is contact dermatitis contagious
Contact dermatitis occurs when the skin comes into contact with an irritant or allergen. In simple (irritant) dermatitis, this is a non-allergic reaction of the direct action of a substance on the skin, without immune sensitization, so a repeat reaction is possible only after new contact with the irritant.
How it is diagnosed and when to see a doctor
The doctor makes the diagnosis based on the appearance of the skin and by asking about the substances you have contacted. For prolonged or recurring dermatitis, patch testing is used: small patches containing possible allergens are applied to the skin, removed after 48 hours, and the reaction is assessed, with a delayed response checked later; for some allergens, such as metals, an additional visit is needed around day 10. Sometimes a biopsy or culture from the affected area is used to rule out other causes. You should see a doctor if symptoms are persistent, recurring, or severe; referral to a dermatologist is made when the cause cannot be found or treatment does not help.
- Redness and itching strictly at the site of contact with the substance
- Blisters, oozing, crusts, or cracks on the skin
- A rash that appears 24–48 hours after contact
- Dry, rough skin on the hands with cracks
- Symptoms that persist or return
Contact dermatitis by itself is not a reason to call an ambulance. Call 103 or 112 for a life-threatening condition.
This material is for reference: it does not replace a doctor's consultation.
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This content is for reference and does not replace a doctor's consultation. Medical disclaimer