Contact Dermatitis: Causes, Pictures & Treatment
Contact dermatitis is inflammation caused by something that touched the skin. It comes in two forms: irritant contact dermatitis, from direct chemical or physical damage, and allergic contact dermatitis, a delayed immune reaction to a substance you have become sensitised to.
Medically reviewed by Dr. Celina Kazumi Iwasa, MD · Last reviewed 2026-08-23
Quick answer
Contact dermatitis is an itchy, red or darkened, sometimes blistering rash that appears where a substance touched the skin. Irritant dermatitis (about 80% of cases) comes from soaps, detergents, solvents or repeated wet work and stings or burns. Allergic dermatitis appears 24–72 hours after contact with an allergen such as nickel, fragrance, preservatives or hair dye and itches intensely. Treatment is identifying and removing the trigger, plus emollients and a topical steroid.
What contact dermatitis looks like
The most useful clue is shape. Contact dermatitis often follows the outline of whatever touched the skin — a rectangle under a watch, a stripe under a bra strap, streaks where a plant brushed the leg, or a band around the wrist. Acute cases can blister and weep; chronic cases become dry, cracked and thickened.
Common locations
- Hands and fingers (the most common site by far)
- Face and eyelids, often from products transferred by the fingers
- Earlobes, wrist and navel from nickel in jewellery and fastenings
- Feet from shoe rubber, glues and dyes
- Any area under a dressing, patch or cosmetic
Typical signs
- Rash with a shape matching the object or product
- Itch, burning or stinging
- Small blisters, weeping or crusting in acute cases
- Dry, fissured, thickened skin in chronic cases
- Clear improvement when away from work or the suspected product
On brown and Black skin
On deeper skin tones the rash may look violet, grey or hyperpigmented rather than red, and long-standing patches often leave marked darkening that fades slowly after the dermatitis is controlled.
Causes and triggers
Irritant dermatitis can happen to anyone given enough exposure; allergic dermatitis only happens once the immune system has been sensitised, after which even tiny exposures provoke a reaction.
| Trigger | Why it matters |
|---|---|
| Nickel | The most common contact allergen worldwide — jewellery, belt buckles, jean studs, phone cases, tools. |
| Fragrance and preservatives | Found in cosmetics, wipes, shampoos and 'unscented' products; a frequent cause of face and eyelid rashes. |
| Soaps, detergents and sanitisers | Repeated wet work and hand hygiene are the leading cause of occupational hand dermatitis. |
| Rubber accelerators and latex | Gloves, elastic waistbands and shoes; affects healthcare, cleaning and construction workers. |
| Hair dye (PPD) | Causes severe scalp, ear and face reactions, sometimes with swelling. |
| Plants | Poison ivy, oak and sumac (urushiol) cause streaky blistering rashes; some plants also cause sun-triggered phytophotodermatitis. |
Conditions that look similar
Distribution and timing separate contact dermatitis from its imitators.
| Condition | How to tell it apart |
|---|---|
| Atopic eczema | Affects skin creases symmetrically, starts in childhood and has a personal or family history of asthma or hay fever. |
| Fungal infection | Ring-shaped with an active scaly edge; a skin scraping confirms it. Steroids alone make it worse. |
| Psoriasis | Well-defined plaques with silvery scale, often with nail pitting. |
| Cellulitis | Hot, tender, spreading redness with fever and feeling unwell — an infection needing antibiotics, not steroids. |
| Shingles | Painful blisters in a single band on one side of the body only. |
Treatment options
Nothing works until the trigger is removed. Once it is, most contact dermatitis clears within two to four weeks with skin-barrier repair and short-term anti-inflammatory treatment.
Identify and remove the trigger
Review everything that touches the affected area, including products you have used for years — sensitisation can develop at any time. A two-week product elimination or a break from a work task is often diagnostic.
Patch testing
For suspected allergy, dermatologists apply standard allergen panels to the back for 48 hours and read them at 48 and 96 hours. This is the only reliable way to confirm an allergic contact allergen.
Topical corticosteroids
A short course of an appropriate potency settles inflammation. Mild steroids for the face and eyelids; stronger ones for palms and soles.
Barrier repair and protection
Frequent fragrance-free emollients, soap substitutes, cotton-lined gloves for wet work and removing rings before washing all speed recovery and prevent relapse.
When it is severe or widespread
Extensive or facial reactions may need a short oral steroid course. Occupational hand dermatitis that does not settle deserves referral for patch testing and workplace adjustment advice.
When to see a doctor
See a clinician if a rash keeps returning, affects your ability to work, involves the face or genitals, or has not improved after two weeks of avoiding the suspected trigger and using emollients.
Red flags
- Spreading redness with fever, pain or swelling (possible cellulitis)
- Widespread blistering or skin peeling
- Facial or eyelid swelling that affects vision
- Rash after hair dye with scalp or face swelling
- Hand dermatitis that stops you working or does not heal
Frequently asked questions
How long does contact dermatitis take to clear up?
Once the trigger is removed, mild contact dermatitis usually improves within a few days and clears within two to four weeks. Allergic reactions to strong sensitisers such as poison ivy or hair dye can take three to four weeks, and thickened hand dermatitis may take longer because the palms heal slowly.
What is the difference between irritant and allergic contact dermatitis?
Irritant dermatitis is direct chemical damage: it can affect anyone, appears within minutes to hours, is confined to the contact area and stings or burns. Allergic dermatitis is a delayed immune reaction that only occurs in sensitised people, appears 24–72 hours after contact, itches intensely and can spread slightly beyond the contact area.
What are the most common contact allergens?
Nickel, fragrance mixes, preservatives such as methylisothiazolinone and formaldehyde releasers, rubber accelerators, para-phenylenediamine in hair dye, topical antibiotics such as neomycin, and plant urushiol from poison ivy, oak and sumac.
Is contact dermatitis contagious?
No. It cannot be passed between people. Poison ivy rash can appear to spread because urushiol resin remains on clothing, tools or pet fur and causes new patches on later contact — the fluid in the blisters is not infectious.
Can contact dermatitis go away on its own?
Yes, if the trigger is removed and the skin is protected while it heals. It will keep recurring as long as exposure continues, which is why identifying the cause matters more than any cream.
Do I need patch testing?
Patch testing is worth doing when a rash keeps recurring without an obvious cause, when it affects your work, or when the suspected allergen matters for future avoidance. It is arranged through a dermatology clinic and takes about a week from application to final reading.
Not sure if it is contact dermatitis?
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Check your skin nowRelated guides
- Contact dermatitis: full clinical A–Z entry
- Eczema (atopic dermatitis)
- Skin rash types: identify a rash by pattern
- Folliculitis
- Skin symptom pictures library
This page is for general information and does not replace a medical consultation. If you are worried about a skin change, see a qualified clinician.