An Overview of Skin Allergies

A woman getting her skin rashes treated

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The term skin allergies refer to a number of allergic conditions, such as eczema, contact dermatitis, and hives, and cause red, itchy skin.

A skin allergy is an allergic reaction to a typically harmless substance, such as wool, pollen, soap, or plants. The immune system reacts to this foreign substance and attacks it to remove it from the body. When your body interacts with a trigger, the result is an allergic skin rash.

Symptoms

A skin rash is the primary symptom of an allergic skin reaction. The rash may start as an itching sensation, a raised bump, or redness, and you might experience any combination of:

  • Rash
  • Itching
  • Redness
  • Swelling
  • Raised bumps
  • Scaling or flaking of skin
  • Cracked skin

Different type of skin allergies present with tell-tale symptoms and patterns that help to determine the type. Eczema, for example, commonly occurs on knees and elbows, whereas contact dermatitis is typically on the hands and face.

Reactions can change over time. While you would expect to develop similar symptoms if you come into contact with the trigger again, you may develop different symptoms at another exposure.

Causes

A skin allergy is caused by contact with a trigger. The immune system responds, causing a rash. Triggers that can lead to skin allergy include:

  • Latex
  • Pet dander
  • Poison ivy or poison oak
  • Cold or hot temperatures
  • Laundry detergent
  • Soap
  • Nickel
  • Chemicals
  • Insects
  • Pollen
  • Sunlight
  • Water
  • Food
  • Drugs

Some people have very obvious triggers, while other people have difficulty determining the source of the problem and need to undergo allergy testing.

The underlying cause of a skin allergy is still under investigation, but new research suggests that some forms of skin allergies may be due to a defect in skin barrier function in infancy.

The underlying cause of skin allergies is still under investigation, but new research suggests it may be due to a defect in skin barrier function development during infancy.

A 2017 review published in Current Allergy and Asthma Reports suggests that both genetic and environmental factors can contribute to damage of the outer layer of the skin, known as the stratum corneum. This may set the stage for the development of eczema and other skin allergies later in life. 

Types of Skin Allergies

There are a few different types of allergic skin conditions and each presents in a specific way.

Eczema

Also referred to as atopic dermatitis, this skin condition most frequently starts in the first couple years of life, but it can first appear in an adolescent or adult.

As a baby, the rash may occur anywhere on the body but most commonly occurs on the extensor surfaces (e.g., knee and elbow), chest, cheeks, and scalp—areas where the child is able to scratch and further irritate the skin. The rash is often red, itchy, scaly, and crusty, and may ooze.

In older children, adolescents, and adults, the rash most commonly occurs in the flexural areas (behind the knees and opposite area of the elbow), though it may also occur on eyebrows, hands, neck, and face.

Scratching and rubbing of the skin may result in an exaggeration of normal skin markings and abnormal pigmentation called lichenification. This may result in a leathery bark-like appearance that is often referred to as “atopic dirty neck.”

Contact Dermatitis

This reaction is most commonly due to an irritant, but an allergic reaction is also possible. Inflammation of the skin results after contact between an allergic trigger substance and your skin.

While the rash can look very similar to eczema, the rash normally only occurs where the skin has had contact with the offending agent. The face, eyelids, neck, hands, and feet are commonly affected areas.

While poison ivy, poison oak, and poison sumac are the most common causes of allergic contact dermatitis, nickel allergy (commonly seen in the jewelry), cosmetics, antibiotic creams, rubber, and chemicals on shoes can also lead to this skin allergy.

Hives

Urticaria, the medical term for hives, is an itchy rash that can indicate a significant underlying medical condition. Hives are raised pink or red bumps that appear in various sizes and shapes and have pale centers.

Hives may quickly change location, size, and shape, and may or may not itch. Hives are not usually significant enough to break the skin.

Hives are generally treated with an over-the-counter antihistamine. It won’t cure the hives, but it will relieve itching and potentially decrease the number of skin lesions. Allergens that may cause hives to include:

  • Food, such as peanuts, eggs, nuts, and shellfish
  • Latex
  • Medications, such as the antibiotics penicillin and sulfa, aspirin, and ibuprofen
  • Insect stings
  • Physical stimuli, such as pressure, cold, heat, exercise, or sun exposure

Hives are not contagious but may be a warning sign of a serious allergic reaction that may lead to anaphylaxis.

Angioedema

Commonly associated with hives, angioedema is a swelling that might involve lips, the eyes, and the hands and feet and can preclude anaphylaxis, a medical emergency that must be treated with an injection of epinephrine. Patients describe angioedema as an abnormal stinging or tingling sensation.

Angioedema of the face or neck indicates a risk of a severe allergy that leads to significant breathing problems. Seek immediate care for any breathing problems or significant worsening of symptoms.

Diagnosis

If you have a rash that may be due to an allergy, your doctor may refer you to a dermatologist or an allergist to determine the trigger. At your appointment, your doctor will examine your skin and ask questions about the products you use, such as detergents, soaps, and skin-care products.

To determine the source of the allergy, your doctor may perform a skin allergy test known as a prick test. A prick test involves a diluted allergen being applied to the skin with a series of needles.

The test usually involves several allergens being tested at once and is done on the arm for adults and on the back for children. The doctor will observe the area for about 15 minutes to check for reactions, such as redness or a wheal or bump.

Treatment

Skin allergies are treated by avoiding allergens when possible, taking preventive medicine such as antihistamines, and managing symptoms as they arise.

Contact dermatitis and eczema are generally not medical emergencies. You can often try over-the-counter antihistamines and anti-itch creams before seeking medical advice or prescription medication. If symptoms do not improve or worsen in one week, see your doctor.

Prescription medications used to treat skin allergy includes topical corticosteroids to reduce inflammation and relieve itching. These drugs include Cordran (flurandrenolide), Psorcon (diflorasone diacetate), Topicort (desoximetasone), and Lidex (fluocinonide), and come as ointments or creams.

For serious allergic reactions, your doctor may prescribe systemic steroids—either oral or by injection—to help decrease swelling and other symptoms.

It is also important to keep irritated skin protected with a moisturizer or barrier, such as petroleum jelly, and to try to avoid contact with irritants, and to avoid hot showers or baths.

A Word From Verywell

Skin allergies can be very bothersome and cause irritating symptoms. Unfortunately, it can take a while to understand what factors are impacting your skin allergies as well as understanding all the different steps needed to get your condition under control. However, understanding basic principles will help you correctly identify the most likely culprit and determine the correct treatment plan.

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Article Sources

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