Armpit rashes can appear in different ways, such as bumpy, smooth, or dry. Causes range from a heat rash to health conditions like psoriasis. Treatment will depend on the cause.

Some armpit rashes can last a few hours and disappear if an irritant is removed. Others occur with a chronic condition, such as psoriasis, and may come and go for many years.

Treatments for arm rashes will depend on the underlying cause and severity of the rash. Some are treatable with home remedies or over-the-counter (OTC) options, while others may need prescription treatment.

Keep reading to discover 12 possible causes of an underarm rash and how to treat them.

Here are some images of some types of rashes that can affect the armpit.

Candida or candidiasis is a fungal or yeast infection. It occurs most frequently, and it affects moist areas of the skin, such as the underarms.

Symptoms of candida may include:

  • swelling
  • itching
  • scaling
  • red or pink rashes on lighter skin tones
  • gray or purple rashes on darker skin tones

Factors that can increase the risk of a candida infection include:

  • hot climate
  • tight clothing or synthetic fabrics
  • insufficient hygiene
  • having a weakened immune system due to age, a health condition, or a medical treatment

Treatment

Treatment for candida usually requires an antifungal cream, but some oral treatments are also available.

Atopic dermatitis, also known as eczema, can affect the armpits.

It happens when a problem with the skin barrier makes the skin more susceptible to irritants and allergens. The skin becomes inflamed and there may be itching, crusting, and dry scaliness. Patches may ooze fluid.

Scratching can worsen symptoms and cause bleeding. If you have eczema, you may experience periods when symptoms worsen or reappear (flare-ups), but have no rash at other times.

Treatment

Treatment for atopic dermatitis usually involves some type of topical medication, such as an anti-inflammatory, corticosteroid, or calcineurin inhibitor.

Other treatments may include:

Seborrheic dermatitis is skin irritation caused partly by the overproduction of sebum, or skin oils. It appears as oily patches of flakes or scales, which may be white or yellow due to the excess oil.

Treatment

Treatment may include creams, foams, gels, and ointments with a type of medication, such as:

  • antifungals
  • corticosteroids
  • calcineurin inhibitors

Some oral medicals and home remedies can also help relieve symptoms.

Contact dermatitis occurs when you come into contact with a foreign substance and you experience a rash on your skin. There are two types:

  • Allergic dermatitis: This type occurs when you come into contact with an allergen, such as nickel and poison ivy. You may also experience other allergy symptoms, such as hives and swelling.
  • Irritant dermatitis: This type is more common and occurs when your skin comes into contact with a toxic material or irritant, such as strong detergents.

The most common type of contact dermatitis under the armpits is a deodorant rash, which may cause burning, itching, or inflammation.

Treatment

The best way to prevent contact dermatitis is to avoid the allergen or irritant. If this isn’t possible, treatment options to help relieve inflammation and itching may include:

  • trying home remedies, such as using fragrance-free soaps
  • applying anti-itch creams
  • taking antihistamines

If these don’t help, a doctor may prescribe a corticosteroid cream.

Heat rashes, also known as miliaria, occur when the sweat glands and ducts become blocked. This leads to sweat-filled bumps under the skin, which can cause pain, itching, and inflammation.

Treatment

Treatment for heat rashes may include moving to a cooler area and wearing breathable clothing. The aim is to prevent overheating and excessive sweating.

Folliculitis is an infection of a hair follicle, where the hair grows out of the skin. There are various possible causes, but the most common is a bacterial infection.

It can happen if an ingrown hair occurs after shaving. It may result in an inflamed bump, which can be painful. Sweating and scratching can increase the risk of folliculitis.

Treatment

Folliculitis usually gets better on its own, but if it develops into a more severe infection, antibiotics may be required.

Inverse psoriasis is an inflammatory condition and a type of psoriatic disease. It can affect areas in skin folds or where skin meets skin, such as the armpits.

It appears as smooth, clearly defined patches on the skin. It looks red on lighter skin but may look gray, purple, or darker in color on darker skin tones. The skin may also be moist, itchy, and soft to the touch. There may also be fissures and an unpleasant smell.

Treatment

There’s no cure for inverse psoriasis, but treatments could help reduce inflammation and symptoms. Treatment may include:

Hidradenitis suppurativa (HS), also called inverse acne, may cause nodules and abscesses to develop under the skin. It often affects the armpits and other areas where skin folds occur.

HS can cause pain, itching, warmth, and an unpleasant smell. There may also be seepage of fluid. Excess sweating may occur around 12 to 48 hours before a new lesion appears.

Risk factors may include:

  • genetics, such as having family members with the condition
  • having overweight or obesity
  • smoking
  • taking certain medications

Treatment

Treatment for HS will focus on treating the underlying cause and addressing any risk factors, such as smoking cessation and weight management.

Some home remedies, such as avoiding tight clothing and applying petroleum jelly-based dressings, may also help relieve HS symptoms.

While not a rash as such, acanthosis nigricans causes the skin to become darker in color and soft to the touch. It’s usually a symptom of an underlying condition, such as diabetes, insulin resistance, obesity, and some autoimmune conditions.

It often affects areas where skin meets skin, such as the armpits and groins.

Treatment

There’s no cure for acanthosis nigricans, but managing your blood sugar levels and other related health conditions may help relieve symptoms.

Sometimes, a topical medication could help the darkened area to fade.

Intertrigo is an inflammatory condition that tends to affect softer skin areas, for example, the armpits, where heat, moisture, and friction occur.

You may start to notice itching, burning, tingling, and pain. An area of inflammation may then develop, and the skin may crack or crust and weep with fluid.

Risk factors may include:

  • having a weakened immune system
  • having limiting mobility
  • having incontinence
  • living in a warm, humid environment
  • having diabetes or obesity

Treatment

Treatment for intertrigo may depend on the underlying cause.

For instance, a doctor may prescribe antibiotics if it’s related to an infection. If it’s caused by excessive sweating, they may recommend a mild antiperspirant.

Ringworm, or tinea corporis, is a fungal skin infection. It can be contagious, but it won’t affect everyone. Children and people with a weakened immune system are more likely to develop ringworm.

It involves an itchy rash that starts as a circle that’s red, grayish, purple, or darker than the surrounding skin, and becomes ring-shaped as the center clears.

Heat, humidity, and fitted clothing may increase your risk of ringworm.

Treatment

A doctor may prescribe topical treatments like clotrimazole, ketoconazole, and miconazole to help treat localized ringworm. If the infection has spread to other body parts, they may prescribe oral medications.

Cutaneous lymphoma is a type of T-cell lymphoma, which is a rare type of non-Hodgkin’s lymphoma, a form of cancer. It may cause bumps, papules, and other growths to appear on the skin. It happens when the immune system isn’t able to defend the skin from fungal and other infections.

Treatment

Treatment for cutaneous lymphoma will depend on the severity and stage of the cancer. Options may include:

It’s important to note that some cancer treatments may also cause rashes. These may be accompanied by symptoms like:

  • itching
  • burning
  • pain
  • blistering
  • changes in skin color and texture

Is it a sexually transmitted infection (STI)?

Some sexually transmitted infections (STIs) can cause a rash anywhere in the body, although not necessarily in the armpits.

Syphilis, for instance, can cause a rash anywhere on the body in the secondary stage. It may appear within 6 months of primary stage sores disappearing, or it might appear while the sores are still healing.

Tips for preventing a rash include the following:

  • Shower regularly and ensure you dry under the arms fully before getting dressed.
  • Use mild skin care and laundry products.
  • Wear loose, cotton clothing that allows your armpits to breathe.
  • Stay in a cool environment.
  • Ask a pharmacist about antichafing powders.
  • Ensure your diet contains vitamins, minerals, and antioxidants to help boost your immune system.
  • Try to manage your weight, as excess skin body fat and skin folds may increase the risk of an armpit rash.
  • Follow any treatment plan for underlying conditions.

Speak with a healthcare professional if you can’t identify the cause of a rash or if it worsens or persists.

What should I put on my armpit rash?

OTC creams and anti-chaffing powder may help relieve symptoms and inflammation. If a chronic condition is causing an armpit rash, speak with a doctor. They could help develop a treatment plan for you.

What does a deodorant rash look like?

A deodorant rash may cause skin discoloration and swelling in the area it’s applied to. This is often accompanied by a stinging, burning, and itchy sensation.

What does a fungal underarm rash look like?

If you see swelling, itching, scaling, or a red, gray, or purple rash, you may have candida. A circular rash could be ringworm. That said, only a doctor can tell you what is causing the rash.

What does lymphoma armpit rash look like?

A lymphoma armpit rash may initially appear as an inflamed patch. As the disease progresses, you may experience nodules, raised plaques, and tumors.

Armpit rashes can happen for many reasons. Living in a warm and humid environment, wearing tight clothes made of synthetic fabrics, and having a weakened immune system, diabetes, or obesity can often increase the risk.

Sometimes, changing a deodorant or moving to a cooler space may stop the rash.

If a rash persists or symptoms are severe, consider seeing a doctor, as it may be a symptom of an underlying condition.