Contact Dermatitis
All information about the causes, symptoms, and treatment of skin irritation caused by exposure to an external agent.
Symptoms and causes
Contact dermatitis is a skin reaction that occurs when the skin is directly exposed to an allergen or irritant. This response consists of a rash that produces itching and, sometimes, a burning sensation.
Symptoms can appear immediately or several days after exposure, making it difficult to identify the triggering agent, which is essential for appropriate treatment.
There are two types of contact dermatitis based on how the body reacts:
- Acute contact dermatitis: the reaction is immediate, occurring right after contact with the irritant or allergen.
- Chronic contact dermatitis: develops from repeated exposure to a mild agent, with cumulative effects. Symptoms are persistent over time.
The prognosis for contact dermatitis is generally good, although chronic cases negatively affect patients’ quality of life.
Symptoms
Symptoms vary depending on the type of contact dermatitis:
- Acute contact dermatitis: the skin reacts immediately at the site of contact with the external agent.
- Skin redness
- Rash
- Blistering lesions, papules, or exudative vesicles that form crusts as they heal
- Intense itching
- Burning sensation
- Increased sensitivity in the affected area
- Chronic contact dermatitis: signs develop gradually across different areas of the skin and persist even when not in contact with the triggering agent.
- Dry skin
- Redness
- Scaling
- Fissures
- Lichenification: thickening and hardening of the skin
Causes
Contact dermatitis occurs when the skin comes into contact with a foreign agent. Depending on the agent, different types of dermatitis arise:
- Irritant contact dermatitis: caused by an irritant without involvement of the immune system; it can affect anyone exposed to the agent.
- Allergic contact dermatitis: the skin reacts due to hypersensitivity to certain agents generally harmless to the body (metals, topical medications, cosmetics, perfumes, detergents, plastics, cement, dyes, resins, latex).
- Phototoxic contact dermatitis: occurs when the skin contacts a photoactive agent (plants, medications, cosmetics, henna) and is subsequently exposed to sunlight. The reaction intensifies with higher amounts of the substance. It can affect anyone, as it is not due to an abnormal immune response.
- Photoallergic contact dermatitis: the immune system recognizes as harmful a compound formed when an agent applied to the skin (medications, perfumes, antiseptics, sunscreens) is altered by sunlight. Prior exposure must have induced hypersensitivity. The reaction is not proportional to the amount of substance applied or sunlight intensity.
Risk Factors
Key risk factors for contact dermatitis include:
- Occupations with prolonged exposure to allergens or irritants: healthcare workers, hairdressers, farmers, construction workers, gardeners, cleaning staff, chefs, mechanics, metalworkers
- Atopic dermatitis: weakened skin barrier
- Dry skin: more susceptible to penetration by external agents
- Skin injuries
- Allergy history
- Genetic predisposition
Complications
Contact dermatitis can lead to infection if the patient scratches the rash.
Prevention
Contact dermatitis cannot always be prevented, especially when linked to immune system disorders. However, risks can be reduced by:
- Avoiding contact with irritants and allergens whenever possible
- Protecting the skin when handling irritants
- Keeping the skin hydrated
- Using mild soaps
Which Doctor Treats Contact Dermatitis?
Contact dermatitis is diagnosed and treated by specialists in Medical-surgical dermatology and venereology, although Allergology may also be involved in some cases.
Diagnosis
The diagnosis of contact dermatitis is primarily clinical. The specialist evaluates the patient’s personal and family medical history, as well as presenting symptoms, and performs a physical examination. In most cases, visual inspection of the rash is sufficient for diagnosis.
To identify the causative substance, Patch Tests are performed. This procedure exposes the patient to small amounts of suspected agents in a controlled manner and monitors the skin’s reaction.
Treatment
Contact dermatitis cannot be cured. Long-term management focuses on avoiding the causative agent or adequately protecting the skin when exposure is unavoidable.
Treatment for skin lesions usually involves topical medications:
- Corticosteroids: relieve itching and reduce inflammation
- Calcineurin inhibitors: help the immune system recover, suitable for sensitive areas as they do not thin the skin
Cold, damp compresses are recommended to aid recovery. Once blisters and inflammation subside, the area should be kept well-hydrated using fragrance-free creams.
In more severe cases, oral corticosteroids or antibiotics may be prescribed.
