Is this cause for concern?
Your underarms should naturally be about the same shade as the rest of your skin. But sometimes, the skin in the armpits can turn a darker hue. Dark underarms usually aren’t a sign of anything serious, but some people may find them embarrassing — especially during tank top and swimsuit season.
Darkening is often due to a skin condition called acanthosis nigricans (AN). It causes skin to thicken and darken in folds around the body.
Common areas of darkening include the:
Back of the neck
Your skin might also itch or have a foul odor in those areas.
Anywhere from 7 to 74 percent of people experience some form of AN, according to a 2014 overview Trusted Source of the condition. The likelihood of developing dark underarms often depends on factors like race, health, and family history.
Keep reading to learn more about why this happens and what you can do.
What causes this condition, and who’s at risk?
Your skin color is determined by pigment cells called melanocytes. When these cells multiply more, they can turn the skin a darker color.
Anyone can develop AN, but some people have a greater risk. People who have darker skin are more likely Trusted Source to have darkening under their arms than people with lighter skin.
AN sometimes runs in families. You inherit it via a faulty gene. You’re more likely Trusted Source to have dark patches on your skin if you have a parent, sibling, or other close relative with the condition.
Although AN is usually genetic or tied to an underlying condition, there’s some evidence Trusted Source to suggest that hair removal may also be a culprit. It’s thought that irritation from repeated shaving or plucking might stimulate excess melanocyte production.
To avoid irritating your underarms, lubricate the skin with a gentle soap or shaving cream before shaving. Apply an unscented moisturizing cream afterward.
You may also be more likely to develop AN because of:
Carrying extra weight makes your body more resistant to the effects of insulin. This hormone helps regulate your blood sugar. High levels of insulin in your blood can lead to increased production of skin pigment cells.
More than half of adults Trusted Source who are 200 percent or more over their ideal body weight experience darkening in their underarms and other skin folds.
Type 2 Diabetes
Obesity is also a risk factor for type 2 diabetes, a disease of high blood sugar. People who develop type 2 diabetes are at an increased risk of AN.
Some conditions that disrupt insulin levels can lead to AN.
Polycystic Ovary Syndrome
Hypothyroidism, an underactive thyroid gland
Certain medications increase your insulin levels, which can lead to underarm darkening.
Corticosteroids, Such as Prednisone (Rayos)
Human Growth Hormone
Birth Control Pills
High-dose Niacin (Niacor)
In rare casesTrusted Source, sudden skin darkening could be a sign of cancer. When this happens, it often affects the stomach, liver, or colon. These tumors increase levels of growth factors that stimulate skin pigment cells.
When AN is caused by cancer, it’s called malignant acanthosis nigricans. You’ll likely see dark patches around your mouth.
How is it treated?
Often, treating the medical condition that caused your dark underarms will fix the issue. A combination of medicines and home remedies could help lighten the color.
Lifestyle changes and Home Remedies
Obesity is one of the leading causes of dark underarms. Losing weight can often fix the problem. Weight loss is an effective way to treat diabetes, too. Talk to your doctor about diet and fitness strategies to help you get down to a healthy weight for your height.
If you suspect that a medication you’re taking is causing your dark underarms, talk to your doctor about switching to another one.
A few natural remedies have been promoted for lightening pigmented skin, including:
Sea Cucumber Extracts
Milk Thistle Extract