Could That Rash Be an Allergic Reaction? (2024)

An allergic reaction, or when your immune system overreacts to a harmless substance, can sometimes manifest in the form of a rash. An allergy rash can be uncomfortable and lead to infections, scarring, and other complications.

The most common allergy rashes include atopic dermatitis (eczema), allergic contact dermatitis, and hives. Common symptoms include a red, itchy, and swollen rash and blisters that ooze and crust. Read on to learn about allergy rashes, including what causes them, symptoms, and treatments.

Atopic dermatitis (eczema) causes flares of itchy, red, and swollen skin. This type of eczema is far more common in children than adults. Atopic dermatitis affects up to 20% of children but only 1% to 3% of adults. About 50% of those with eczema also have food allergies and hay fever (seasonal allergies).

Atopic dermatitis symptoms may include:

• Blisters that ooze and crust
• Bumpy skin on the back of your arms and front of your thighs
• Changes in skin tone
• Discharge and bleeding from the ears
• Dry skin
• Raw skin from scratching
• Redness and inflammation
• Thick, leathery skin

Where an atopic dermatitis breakout occurs might depend on your age. The rash usually forms on the face, feet, hands, and scalp in young children. Adolescents and adults, in contrast, typically develop a rash on the eyelids, elbows, genitals, hands, and knees.

2. Allergic Contact Dermatitis

Allergic contact dermatitis is a common allergy-related rash that's caused by coming into contact with an allergen. People with skin problems like sensitive skin might be more prone to allergic contact dermatitis than others.

Contact dermatitis symptoms include:

• Blisters that ooze, drain, and crust
• Raw, scaly, and thick skin
• Red bumps
• Red, streaky, or patchy skin where the allergen made contact
• Severe itching, burning, and pain
• Warm and tender skin

You may not see a skin reaction right away. It could take one to two days after exposure for the rash to develop.

Hives are slightly raised, itchy red bumps (wheals) that develop in response to an allergen. Wheals can grow bigger, spread, and join together to form a large rash. These bumps are temporary and usually go away after you are no longer exposed to the allergen.

Triggers

People with atopic dermatitis frequently have other allergic conditions. Seasonal allergies, for example, do not cause atopic dermatitis but may worsen symptoms. Other triggers include cold and dry air, dry skin, emotional stress, fragrances and dyes, sudden changes in temperature, and viral infections.

A number of triggers may cause allergic contact dermatitis, including:

• Adhesives
• Fabrics and clothing
• Fragrances
• Hair dye and nail polish
• Nickel and other metals
• Preservatives
• Rubber and latex
• Topical antibiotics

There's a rare form of contact dermatitis that does not require direct contact with the skin to cause a flare. Airborne contact dermatitis is caused by coming into contact with aerosolized plant resins from sunflowers, ragweed, and goldenrod.

Certain foods, insect bites, medicine, pet dander, and pollen may trigger acute (short-term) hives. Chronic (long-term) hives, in contrast, are typically caused by emotional stress and excess sweating.

A healthcare provider can examine your skin and use an allergy skin test to figure out the cause of your allergy rash. Types of allergy skin tests include:

• Intradermal skin test: This test is mostly used to confirm allergies to bee venom and penicillin. A healthcare provider will inject a small amount of an allergen into your skin.
• Patch testing: A healthcare provider will tape allergens to your skin for 48 hours and check your skin for a reaction after 72–96 hours. This type of testing is especially good for helping evaluate the causes of allergic contact dermatitis.
• Skin prick test: A healthcare provider will prick your skin so a small amount of an allergen enters. They will examine your skin for a reaction, which typically occurs within 15–20 minutes.

Treatment

Avoiding triggers is key to preventing an allergy rash. A number of treatments are available to treat atopic dermatitis, allergic contact dermatitis, and hives.

Common treatment options include:

• Topical moisturizers: If you have eczema, your healthcare provider may prescribe a topical moisturizer. These moisturizers help reduce itching, redness, and swelling.
• Steroids: A healthcare provider may prescribe a topical or oral steroid to reduce inflammation in people with atopic dermatitis and allergic contact dermatitis.
• Cool compress: Apply a cool compress to the affected area to relieve itching from allergic contact dermatitis.
• Lotion: If you have eczema, t's important to keep your skin hydrated. Reapply lotion two to three times per day. Avoid products that contain alcohol, dyes, scents, and other chemicals.
• Calamine lotion and colloidal oatmeal baths: These home remedies can be soothing on the skin for people with allergic contact dermatitis.
• Antihistamines: These medicines block the effects of histamine, a chemical your body releases in response to an allergen. Antihistamines can relieve itching from an allergy rash.

Hives typically go away on their own. It's essential to avoid hot baths or showers and tight clothing, which may irritate your skin. A healthcare provider may prescribe systemic medications like oral dapsone or an injection called Xolair (omalizumab).

You can typically treat an allergy rash at home. The rash usually clears up as soon as you remove the allergen from your environment. It's important to see a healthcare provider, however, if your rash does not respond to treatments that usually work, such as antihistamines or topical steroids.

You'll also want to contact a healthcare provider if you have symptoms like a rash that:

• Affects your eyes, genitals, lips, or mouth
• Blisters
• Causes open sores and raw skin
• Is painful
• Occurs with a fever
• Spreads quickly and over most of your body

See a healthcare provider if you develop signs of an infection, including pus-like discharge and skin that's red, swollen, and warm. Get medical attention right away if you are having a severe allergic reaction, including trouble breathing.

Other Causes of Skin Rashes

Allergens are a common cause skin rashes, but an underlying illness or infection may be the culprit in some cases. Some people develop a skin rash in reaction to certain medicines or insect bites and stings.

Other causes of skin rashes include:

• Childhood illnesses: These include chickenpox, hand-food-mouth disease, measles, and scarlet fever.
• Impetigo: This bacterial infection causes red sores that blister, ooze, and crust. Impetigo typically affects children.
• Kawasaki disease: This rare illness causes inflammation of the blood vessels, typically in children.
• Lupus: This autoimmune disorder causes the immune system to accidentally target and attack healthy cells in the skin, kidneys, joints, and more.
• Psoriasis: This skin condition causes thick, red patches of skin and silvery scales.
• Rheumatoid arthritis (RA): This type of arthritis causes inflammation of the joints and nearby tissues.
• Shingles: This is a painful rash caused by the varicella-zoster virus (VZV). This virus causes chickenpox and lays dormant in your nerve cells after the initial infection.
• Systemic infections: These are bacterial, fungal, or viral infections that affect the entire body.

Atopic dermatitis, allergic contact dermatitis, and hives are common allergy rashes. You may develop a red, itchy, and swollen rash and blisters that ooze and crust in response to an allergy. An underlying condition, such as lupus, psoriasis, or shingles, may be the culprit in some cases.

If you are unsure what's causing your allergy rash, visit a healthcare provider. They can administer a skin allergy test to determine what you are allergic to.

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