Skin tags form in the armpit because it’s one of the body’s highest-friction zones. Skin rubs against skin with every arm movement, and that constant irritation triggers small, benign growths made of loose collagen fibers and tiny blood vessels. The armpit is one of the most common locations for skin tags, alongside the neck, groin, and under the breasts, all spots where skin folds create persistent contact.
How Friction Creates a Skin Tag
A skin tag is essentially a small pouch of skin that gets pushed outward. Repeated rubbing stimulates the outer layer of skin to thicken and the underlying connective tissue to loosen and bulge. Blood vessels dilate to supply the growing tissue, which is why skin tags bleed more than you’d expect for their size if nicked or cut. Over time, the tag develops a narrow stalk connecting it to the surrounding skin.
Clothing adds to the problem. Tight or synthetic fabrics in the underarm area increase friction beyond what skin-on-skin contact alone produces. If you already have a small tag, ongoing friction from sleeves or bra straps can cause it to grow larger.
Weight, Metabolism, and Skin Tags
Carrying extra weight is one of the strongest predictors of skin tags, and it works through two pathways. First, more body weight means more skin folds and more friction. Second, excess weight is closely tied to insulin resistance, which appears to drive skin tag formation independently of friction.
The metabolic connection is significant. A study from Eastern India found that people with skin tags were over 11 times more likely to have metabolic syndrome (a cluster of conditions including high blood sugar, high blood pressure, and excess abdominal fat) compared to people without skin tags. In a separate Irish study of patients in a weight management clinic, 85 out of 100 participants had skin tags on their neck or armpits. Among those with type 2 diabetes, 94.6% had skin tags, compared to 79.4% of those without diabetes. Nearly 59% of participants with skin tags had diabetes, versus just 13% of those without any tags.
This doesn’t mean a skin tag signals diabetes. Most skin tags are nothing more than a friction-related nuisance. But if you’re developing multiple skin tags, especially in several body areas at once, it may be worth checking your blood sugar and metabolic health with your doctor.
Hormonal Changes During Pregnancy
Pregnancy is a well-known trigger. Rising levels of estrogen and progesterone stimulate skin cell growth, and the combination of hormonal shifts with pregnancy-related weight gain creates ideal conditions. As the body expands, new skin folds form in the armpits, under the breasts, and along the neck, increasing friction right when hormones are already priming the skin to grow. Skin tags that appear during pregnancy sometimes shrink or fall off after delivery, though many persist.
Genetics and Age
Some people are simply more prone to skin tags than others. They tend to run in families, and they become more common with age. Most people who develop them are over 30, and prevalence continues to rise through middle age. If your parents dealt with skin tags, your chances are higher regardless of your weight or activity level.
How to Tell It’s Actually a Skin Tag
A skin tag is soft, flesh-colored or slightly darker, and hangs from the skin on a thin stalk. It moves freely when you touch it and is painless unless something snags it. They typically range from a few millimeters to about the size of a grape, though most stay small.
A few other growths can appear in the armpit and look similar at first glance:
- Warts are caused by a virus and tend to have a rough, bumpy surface. They sit flat against the skin rather than dangling from a stalk.
- Moles are usually darker, flatter, and more firmly attached. A mole that changes in size, shape, color, or symmetry warrants a dermatologist’s evaluation, since those changes can signal skin cancer.
- Swollen lymph nodes feel like firm lumps under the skin rather than growths on the surface. They’re deeper and often tender.
If a growth in your armpit is hard, painful, rapidly changing, or multicolored, it’s worth getting a professional look. A straightforward skin tag, though, is almost always harmless.
Why You Shouldn’t Remove It Yourself
It’s tempting to snip a skin tag with scissors or tie it off with string, but dermatologists at UCLA Health warn against it. Skin tags have their own blood supply, and sometimes nerves. Cutting one at home can cause surprisingly heavy bleeding that’s difficult to stop, along with a real risk of infection. Tying off a tag with thread or dental floss can lead to prolonged pain and tissue damage if done incorrectly.
Professional Removal Options
If a skin tag bothers you cosmetically or keeps getting irritated by clothing, a dermatologist can remove it quickly in the office. The three most common approaches, according to the American Academy of Dermatology:
- Freezing (cryosurgery): Liquid nitrogen is applied to the base of the tag, destroying the tissue. A small blister or scab forms and falls off within a week or two, taking the tag with it.
- Electrodesiccation: A tiny needle delivers an electrical current that destroys the tag. A scab forms and heals within one to three weeks.
- Snipping: The area is numbed, and the tag is cut off with sterile scissors or a blade. A solution is applied to stop bleeding immediately.
All three methods are quick, with minimal discomfort and short healing times. Insurance typically doesn’t cover removal since skin tags are considered cosmetic, but the procedure is relatively inexpensive.
Reducing Your Risk of New Skin Tags
You can’t eliminate the possibility entirely, especially if genetics are working against you, but a few practical steps lower the odds. Keeping the armpit area dry and reducing friction helps. Loose-fitting, breathable fabrics create less irritation than tight synthetic materials. Maintaining a healthy weight reduces both the mechanical friction from skin folds and the metabolic factors that promote skin tag growth. The two most significant metabolic predictors in research were increased waist circumference and low levels of HDL (the “good” cholesterol), both of which respond to regular exercise and dietary changes.