What Allergy Causes Bumps on Arms?

Hives (urticaria) and eczema are most common types of allergic reactions that can cause bumps on the arms.

Bumps on the arms can have a number of causes, including allergies. The two most common types of allergic reactions that can cause bumps on the arms include hives (urticaria) and eczema. 

• Hives are a skin reaction characterized by slightly raised, smooth, red bumps that tend to itch. They are usually temporary and will go away on their own within several hours, or at worst, after a few days, though they may recur over several weeks. When episodes of hives last more than six weeks, it is considered chronic hives (chronic urticaria).
• Eczema (also called atopic dermatitis) refers to a group of chronic skin conditions that cause itchy, red, inflamed, scaly skin. When bumps form on the skin (papules), it is often referred to as papular eczema. People who develop eczema often have environmental triggers to common allergens.

Common allergens that can cause bumps on the arms include:

• Food allergies
  • Peanuts
  • Tree nuts
  • Shellfish
  • Eggs
• Drug allergies 
  • The most common drugs that cause allergic reactions include: 
    • Non-steroidal anti-inflammatories (NSAIDs)
    • Angiotensin converting enzyme (ACE) inhibitors
    • Penicillin antibiotics 
    • Sulfa antibiotics
    • Aspirin
    • HIV medications
    • Anti-seizure medications (anticonvulsants)
• Physical contact (contact hives), an allergic reaction that occurs when a substance comes into contact with the skin
• Allergic reactions to insect bites or stings
• Pet dander 
• Dust mites

Treatment for allergic bumps on the arms depends on the cause. 

The easiest way to treat hives (urticaria) is to avoid known triggers. 

Medications may be used to control itching caused by hives, including:

• Antihistamines (H1 antagonists) 
• H2 antagonists 
  • Not usually used alone for hives, but may be combined with an antihistamine because the combination can be more effective than an antihistamine alone
• Corticosteroids 
• Sympathomimetics for severe hives or anaphylactic reactions
• Tricyclic antidepressants 
• Monoclonal antibodies 
• Immunomodulatory and anti-inflammatory therapy 

Eczema is a chronic condition that can periodically worsen (flare) in between times of mild to no symptoms. There is no cure for eczema but it can be managed with home care and medications. 

Home remedies to relieve or reduce symptoms of eczema may include: 

• Identifying and avoiding triggers 
• Keeping the skin hydrated
• Emollients
• Bathing
• Lukewarm baths or showers can hydrate the skin and may relieve itching
• Wet dressings (wet wraps) to help soothe and hydrate skin, reduce itching and redness, loosen crusted areas, and prevent skin injury due to scratching

Medications used to treat eczema include:

• Over-the-counter (OTC) or prescription topical steroid creams or ointments 
• Over-the-counter (OTC) or prescription oral antihistamines for itching 
• Oral steroids may be used for a short duration to treat severe flares
• Tacrolimus ointment (Protopic) and pimecrolimus cream (Elidel)
• Injectable biologics for adults with moderate to severe eczema that has not responded to other treatments
• Immunosuppressive drugs for patients with severe eczema who do not improve with other treatments

Ultraviolet light therapy (phototherapy) may be used to help control eczema in patients who have severe eczema that does not respond to other treatments because it is expensive and may increase the risk of developing skin cancer.