An Overview of Skin Allergies

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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 trigger and attacks to remove it from the body. The result is an allergic skin rash, which tends to be red and itchy. Skin allergies encompass a number of allergic conditions, such as atopic dermatitis, contact dermatitis, and hives.

A woman getting her skin rashes treated
MilosBataveljic / Getty Images

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 ultimately experience any combination of:

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

Different types of skin allergies present with telltale symptoms and patterns that help to determine the type.

Reactions can change over time. While you might expect to develop similar symptoms if you come in contact with the trigger again, you may develop different symptoms after 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.

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.

In older children, adolescents, and adults, the rash most commonly occurs in the flexural areas (behind the knees and in elbow creases), 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.

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 in 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. The itching from hives doesn't usually cause a person to scratch enough to break the skin.

Allergens that may cause hives 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—a medical emergency that must be treated with an injection of epinephrine.

Angioedema

Commonly associated with hives, angioedema is a swelling that might involve lips, the eyes, and the hands and feet and can preclude anaphylaxis.

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 skincare products.

Patch testing is used to determine the cause of contact dermatitis, which is a delayed type of hypersensitivity reaction caused by T-cells (lymphocytes).

The patch consists of a variety of different allergens which are applied in little dots on an adhesive sheet. Each patch is applied to the person's back and remains there for 48 hours. During this time, it is important not to get the patches wet, so showers, baths, and excessive sweating need to be avoided.

After 48 hours, the patches will be removed at the doctor's office. Before doing so, the location of each patch will be marked with an indelible surgical marker. This will provide the doctor with a reference when you return to the office for a final evaluation.

The final evaluation will be performed anywhere from 72 to 96 hours after the initial placement. Any reaction will be noted by the doctor, providing insights as to which substances to avoid and the types of treatments to be considered.

Patch testing is painless and, unlike allergy tests, does not involve needles of any sort. Children can be tested once they are old enough to under

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. Prescription medications used to treat skin allergy include topical corticosteroids to reduce inflammation and relieve itching. These drugs, which come as ointments or creams, include:

  • Cordran (flurandrenolide)
  • Psorcon (diflorasone diacetate)
  • Topicort (desoximetasone)
  • Lidex (fluocinonide)

Hydrocortisone, which is in the same category, is available over-the counter.

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 (e.g., petroleum jelly), 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 and what you need to do to get your condition under control. However, understanding these basics can help you correctly identify the most likely culprit and determine the correct treatment plan with your doctor.

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