Infected ingrown hairs, shingles, and contact dermatitis from an allergic reaction are common causes of armpit blisters. These types of sores can also sometimes result from certain insect bites, particularly those from ticks or mosquitoes. Fungal or bacterial infections on the skin's surface can cause blisters in people who sweat excessively, though these conditions are normally cleared up easily with a topical cream. A severe armpit rash with blisters can be a sign of a more serious illness in some rare cases, so anyone with numerous large blisters is often advised to consult with a medical professional.
Underarm areas that are frequently shaven are sometimes prone to rashes, ingrown hairs, and increased skin sensitivity. A blister can often form from an ingrown hair that becomes infected, and this common problem is treated fairly easily. Many ingrown hairs will resolve themselves with gentle exfoliation and the application of a topical cream containing antibacterial ingredients, such as salicylic acid. Most dermatologists advise against lancing or extracting ingrown armpit hairs because this can often worsen the initial infection. Preventative measures include careful shaving with a sharp single-blade razor and avoiding running the razor over the same skin area more than once.
Shingles is a skin condition resulting from a viral infection that leads to rashes and itchy, painful blisters over several areas of the body, including the armpits. Treatments for this condition usually include topical medication to help relieve the itching and sometimes corticosteroid injections to shorten the duration of the blister outbreaks. Although these kinds of blisters can be especially bothersome in many cases, dermatologists often warn shingles sufferers not to scratch or shave the area to avoid further infection or scarring.
Allergic reactions can often be responsible for armpit blisters in patients with histories of skin sensitivities, and certain chemicals in roll-on or spray deodorants can frequently cause these kinds of reactions. The same problem can happen from heavy uses of fragrant body sprays, colognes, or perfumes. People who initially suffer from this kind of allergic reaction sometimes need to determine the product responsible by a process of elimination. Blisters from reactions to perfume products are normally relieved by not using those products. Some dermatologists prescribe specialty deodorants formulated for patients with skin allergies, and others recommend all-natural products that can usually be found in health food stores.