Contact dermatitis is an inflammatory skin condition that results from contact with an irritating substance. Chemicals, heat, and substances a person may be allergic to can all cause contact dermatitis.

While most people will not experience a major allergic reaction from the majority of irritants, the effects of contact dermatitis can be unpleasant until they subside.

This article outlines the types of contact dermatitis, their appearance, what may trigger them, and how someone can treat or prevent occurrences.

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There are several common types of contact dermatitis. These typically vary depending on the agent involved.

Irritant contact dermatitis

Irritant contact dermatitis is a nonspecific skin response to skin damage by irritants. It is the most common type of contact dermatitis and accounts for about 80% of all cases.

Many external factors may cause irritant contact dermatitis, including:

  • chemicals
  • friction
  • heat
  • repeated exposure to weak irritants

A person with irritant contact dermatitis may experience a rash that may sting or burn.

This type of contact dermatitis may be more common for people whose occupations expose them frequently to irritants, such as healthcare workers, hairdressers, and cleaners.

Allergic contact dermatitis

Allergic contact dermatitis involves a delayed hypersensitivity reaction in response to allergens. It occurs when the immune system produces an allergic reaction to a substance or chemical.

Poison ivy is the most common cause of allergic contact dermatitis. Nickel and rubber gloves are also common causes.

Many everyday products contain preservatives and other substances that can cause allergic reactions. As a result, many people may not be aware of what exactly is causing their allergic reaction without a diagnosis.

Photocontact dermatitis

Photocontact dermatitis occurs when a person comes into contact with a substance and sunlight at the same time. These irritants or allergens may be external, such as some sun lotions, or the result of ingested medications.

In photocontact dermatitis, exposure to sunlight is necessary to trigger the irritant or allergic reaction.

In nearly all cases of contact dermatitis, a rash will develop after exposure to an allergen or irritant. This rash may appear red on lighter skin tones, while on darker skin tones, it may appear dark brown, purple, or gray.

In most cases of contact dermatitis, the rash can be discolored and itchy, and it may sting. If exposure to an irritant or allergen continues, the skin may harden.

Additionally, contact dermatitis may lead to:

Below are some images of contact dermatitis.

Triggers will vary from person to person and according to the type of contact dermatitis. As a result, a person needs to identify their triggers to avoid contact with the substance in the future.

According to the National Eczema Association, common triggers for types of contact dermatitis include the following:

Irritant contact dermatitisAllergic contact dermatitis
solvents, detergents, or bleachpoison ivy, poison oak, and poison sumac
hair dyenail polish
over-washing the hands with hot water and soapcertain preservatives, such as thimerosal
scratchy fabricsmedications that people apply to the skin

Triggers for irritant contact dermatitis involve substances that damage skin cells, whereas triggers for allergic contact dermatitis cause a delayed allergic response.

Chemical irritants

Toxic or corrosive substances may lead to irritant contact dermatitis. A person may encounter these as part of their profession or at home.

Potential chemical irritants include:

  • bleach
  • hand sanitizer
  • battery acid
  • detergent
  • kerosene
  • drain and other cleaners

Photocontact dermatitis triggers

However, irritant reactions are not limited to toxic or corrosive substances. As mentioned, photocontact dermatitis requires the presence of an irritant and exposure to sunlight.

Photocontact dermatitis can occur in two types — phototoxic contact dermatitis and photoallergic contact dermatitis — depending on whether a immunological reaction is present.

Examples of irritants that may react to sunlight include:

The rash and other reactions will typically disappear after exposure to the substance ends.

However, the symptoms that contact dermatitis causes may take time to heal after the initial exposure ends. This will take longer if irritants damage the skin.

Should the symptoms of contact dermatitis cause discomfort, a person may be able to relieve them with home remedies or over-the-counter (OTC) treatments, including:

In severe cases, a person may need to see a dermatologist, an allergist, or another healthcare professional. They can prescribe ointment, creams, or prescription medications to treat contact dermatitis.

In most cases, prevention is as simple as avoiding the substance or object that caused the contact dermatitis. For example, a person who develops a rash after coming into contact with poison ivy should avoid the plant.

However, a person may not always know what caused the reaction. In these cases, a dermatologist may be able to identify the allergen or irritant causing a person’s dermatitis.

They may do so by assessing a person’s medical history and lifestyle habits or performing patch testing.

Contact dermatitis causes inflammation of the skin. It results from contact with an irritating substance and can lead to an itchy rash or even blisters.

A person may also experience contact dermatitis due to an allergic reaction to a substance, such as a preservative in skin care products or a certain plant. Chemicals and other corrosive agents may also cause contact dermatitis.

In rare cases, a combination of an irritant and sunlight exposure may cause a rash. Medical professionals refer to this as photocontact dermatitis.

In general, people can treat contact dermatitis by avoiding known irritants. They may also manage the symptoms with OTC medications and creams.