Allergy-causing itchy rashes in the armpits may be due either to irritant type or allergic type of contact dermatitis. Irritant contact dermatitis means a direct irritating effect on the skin. Usually it is dose dependent, meaning the higher the concentration of the irritating substance, the higher the irritant reaction and rash. Allergic contact dermatitis is caused by prior sensitization to a chemical substance; it is not dose-dependent.
Itchy, red skin rashes may occur at other body sites also in the case of allergic contact dermatitis of the armpits, in contrast to the contact irritant dermatitis, where the allergic response is limited to the area of application only.
Irritant Contact Dermatitis Causing Itchy Rashes in the Armpits
Irritant contact dermatitis of the underarm can occur within minutes to a few hours of coming into contact with an allergen. Usual culprits for irritant contact dermatitis of the armpits are deodorants, detergents and clothes. It is not unusual for people to apply caustics like undiluted Dettol or other antiseptic lotions to the axillary fold. This causes a stinging and burning sensation initially and itching later on. The skin can get badly burnt with caustic applications.
Most often, however, the signs of contact irritant dermatitis are redness, oozing and swelling of the armpits, later followed by flaking and crusting of the skin.
Treatment of itchy armpit rashes caused by irritant contact dermatitis involves the following:
- How to prevent underarm itching caused by contact irritant dermatitis rashes: The preventive measures include avoidance of further contact with the irritant, washing with copious amounts of water immediately after contact with a suspected irritant and use of barrier creams.
- Treatment of skin rashes causing itchy armpits due to contact irritant dermatitis depends upon the stage of the disease. In acute oozing stage, the blisters are drained (retaining the roof) and cleansed with Burrow’s solution or dilute potassium permanganate solution. Application of moderate strength topical steroids provides faster relief. Your doctor may prescribe a short course of oral prednisolone if the reaction is severe. Once the healing of the skin rash has taken place and the affected skin has peeled off, continue applying a barrier cream to avoid recurrences of the rash and itching of the underarms. For chronic irritant contact dermatitis, topical tacrolimus or pimecrolimus are useful steroid sparing agents in getting rid of the skin rash and itching.
Allergic Contact Dermatitis Causing Skin Rashes and Itchy Armpits
Allergic contact dermatitis is caused by re-exposure to a chemical or herbal substance to which you were sensitized earlier. For the first instance exposure, it will take seven to 10 days for the allergic contact dermatitis rash to occur after coming into contact with the allergen. According to the North American Contact Dermatitis Group, the following are the top ten substances that cause allergic skin rash through contact dermatitis in the US:
- Nickel sulfate, a common component in alloys used to manufacture metallic button and clips, jewelry, watch straps etc.
- Neomycin sulfate, a common component of creams and ointments.
- Balsam of Peru: Present in topical medications and cosmetics.
- Various fragrances contained within cosmetic creams, lotions and sprays, especially deodorants.
- Thiomersol present in antiseptic topical applications.
- Sodium gold thiosulfate in medications.
- Formaldehyde in disinfectants, plastics and curing agents.
- Quaternium-15 in disinfectants.
- Cobalt chloride , component of cement, industrial oils, cooling agents, eye shades etc, and,
- Bacitracin, present in antiseptic ointments and topical powders
- There are many other chemical substances that cause sensitization and allergic rashes in the skin. In itching and allergic reactions of the armpits, the main culprits are fragrances in deodorants and topical applications. Contrary to popular belief, many natural and herbal topical applications may cause contact dermatitis in sensitive individuals. Textile additives and dyes can also cause allergic itchy armpits.
Treatment of rashes and itchy armpits caused by allergic contact dermatitis involves identification and removal of the causative agent and topical or systemic steroids, as discussed in the treatment of contact irritant dermatitis.
Heat and Sweat Rash Causing Underarm Itching
Exposure to heat and excessive sweaty armpits (axillary hyperhidrosis) can cause itching of the armpits, with or without skin rashes. Heat rashes appear as minute, red bumps, more prominent in the apposed surfaces of the axilla. Burning and stinging sensations are common initial symptoms of heat and sweat rashes.
Treatment of heat rashes involves avoidance of hot, humid outdoor activities, especially during the peak hours, and application of dusting powders, mild topical steroids and oral anti-itching medications like cetrizine. Cleansing the area with cool water immediately after coming indoors will help prevent heat rashes in most cases.
In addition to the different types of contact dermatitis, armpit rash and itching may also be caused by skin infections, certain skin diseases and systemic illnesses.