Types of Skin Allergies

Various types of skin allergies can cause rashes, itchiness, and inflammation. Different conditions affecting the skin can cause itchiness and rashes, but only some are related to an allergy.

However, not all rashes that itch are related to skin allergies. Insect bites and autoimmune conditions, along with fungal, bacterial, and viral infections, can all cause an itchy rash. 

While there may be other reasons for your rash, allergic reactions are still among the most common causes of skin rashes.

This article reviews the most common skin rashes and shows pictures of each.

Causes of Skin Allergy

Skin allergies can be caused by many things, including coming in contact with certain plants (like poison ivy or poison oak) and metals or having an allergic reaction to a medication or food.

Nickel, a metal found in jewelry, clothing fasteners like zippers or snaps, and cell phones, is responsible for many skin allergies.

Four common types of skin allergy include contact dermatitis, eczema, hives, and swelling.

Contact Dermatitis

Contact dermatitis happens when the skin comes into direct contact with a substance that causes a reaction. People react to a variety of chemicals, including cosmetics, hair dye, metals such as nickel, topical medications, and dental materials.

An example of contact dermatitis is a rash from poison ivy, which is extremely itchy and appears as blisters that ooze and crust after contact with plants of the Toxicodendron family.

Symptoms

Symptoms can include a rash, blisters, itching and burning. The rash is typically located only in the area of contact with the offending substance. Common locations include the face, especially the eyelids, neck, hands, and feet.

Contact dermatitis to metals, such as in jewelry or snaps/buttons/zippers on clothing, commonly occurs on the neck, wrists/hands, piercing holes, and at the waistline.

Treatment

Contact dermatitis can be diagnosed through a patch test, though it can be difficult to determine the point of contact with the allergen. Contact dermatitis is treated in the following ways:

• Avoid the irritant.
• Avoid scratching the affected area (this can worsen the rash or cause an infection).
• Use cool compresses, anti-itch medications, and oatmeal baths to relieve itching.
• Apply fragrance-free moisturizer or barrier repair cream after washing.

Eczema

Eczema, also called atopic dermatitis, frequently occurs before the age of 5 (although it may start in young adults) and can continue into adult life. This rash occurs most often where the skin flexes — inside the elbows, behind the knees, and in the front of the neck.

In infancy, the rash most often occurs on the cheeks and/or scalp. Older children and adults typically have the rash in the skin folds of the elbows and behind the knees, although it may also occur on the ​face, neck, hands, feet, and back.

Symptoms

The rash causes severe itching, redness, oozing, and flaky scales. These symptoms can be painful and can cause changes in skin color and blisters. There are often excoriations, or areas of broken skin, from aggressive scratching.

Treatment

In mild cases, eczema may be treated with ointments and moisturizers (emollients). With more severe eczema, a healthcare provider may recommend prescription medication, including topical steroids and/or antihistamines.

In rare cases, allergic triggers (including contact allergens and environmental exposures) may also be identified that upon removal may significantly improve rash symptoms.

Hives (Urticaria)

Urticaria, commonly referred to as hives, is an itchy rash that can occur at any age. Urticaria can be acute (lasting less than six weeks) or chronic (lasting more than six weeks). 

Symptoms

This rash appears as swelling of the surface of the skin into red- or skin-colored welts (called wheals) with clearly defined edges. These raised bumps can be of various shapes and sizes and last for minutes to hours, but not usually more than 48 hours. While it can be very itchy, a person with hives will generally not scratch enough to break the skin and cause bleeding.

Treatment

Mild cases of hives will likely go away on their own in a few days. To reduce itching and swelling:

• Use cool compresses, anti-itch cream, and oatmeal baths.
• Use lukewarm water and avoid rubbing with a washcloth, loofah, or mesh sponge when taking a shower or bath.
• Use fragrance-free soap, cleansers, and moisturizers.
• Do not wear tight-fitting clothing, which can irritate the area.
• Your provider may suggest that you take an antihistamine such as diphenhydramine (Benadryl) or cetirizine (Zyrtec). Follow your provider's instructions or the package instructions about how to take the medicine.
• Other oral prescription medicines may be needed, especially if the hives are long-lasting.

If your reaction is severe, especially if the swelling involves your throat, you may need an emergency shot of epinephrine (adrenaline) or steroids (like prednisone). Hives in the throat can block your airway, making it difficult to breathe.

Swelling (Angioedema)

Swelling, also called angioedema, is similar to hives, but the swelling is under the skin instead of on the surface. It can occur with hives or it may be caused by an allergic reaction. It often involves the lips, eyes, hands, and feet.

Symptoms

In cases where angioedema presents at the same time as hives, the swelling usually feels itchy. In cases where angioedema presents without urticaria, it can feel itchy or it may burn, sting, or cause a tingling sensation instead.

In rare cases, severe swelling around the throat can block the ability to breathe. This is a medical emergency known as anaphylaxis, which requires immediate medical attention and can be life-threatening.

Treatment

Mild symptoms may not need treatment. Moderate to severe symptoms may need to be treated with the following:

• Avoid any known allergen or trigger that causes their symptoms.
• Avoid any medicines, herbs, or supplements that are not prescribed by a provider.
• Cool compresses or soaks to relieve pain.

Medicines used to treat angioedema include:

• Antihistamines
• Anti-inflammatory medicines (corticosteroids)
• Epinephrine shots (people with a history of severe symptoms can carry these with them)
• Inhaler medicines that help open up the airways

Seek medical help right away if throat swelling causes difficulty breathing.

Summary

Skin rashes can be alarming, particularly if you're having an allergic reaction to a substance you encounter in your daily life. Because there are different types of rashes, it's important to understand which type of rash you have and which treatment will work best.

If you do not have a history of skin allergies, it's important to work with a healthcare provider to learn what is causing your rash so you can avoid it and prevent future reactions.