Skin tags, sometimes called “tag moles” because of their mole-like appearance, are small benign growths caused primarily by friction, metabolic changes, and hormonal shifts. They are not true moles. While moles form from pigment-producing skin cells, skin tags develop from loose collagen fibers and blood vessels that get pushed outward beneath the skin’s surface, creating a soft, flesh-colored flap that often hangs by a thin stalk.
Skin Tags vs. True Moles
The confusion between skin tags and moles is understandable. Small moles on a stalk can look nearly identical to skin tags, and without a biopsy, even clinicians sometimes can’t distinguish between the two. The key visual differences: moles tend to be flat or slightly raised with a distinct pigmented color (brown, black, or dark pink), while skin tags are usually skin-colored or slightly darker, soft to the touch, and dangle from a narrow base. Skin tags also cluster in areas where skin rubs against itself or against clothing, while moles can appear virtually anywhere.
Under a microscope, the distinction is clear. Skin tags are made up of loosely arranged collagen fibers with dilated blood vessels and lymphatic channels, all covered by a thin outer layer of skin. Moles, by contrast, are clusters of melanocytes, the cells that give skin its color. This structural difference matters because it points to completely different causes.
Friction Is the Primary Trigger
Repeated rubbing of skin against skin or against fabric is the most common cause of skin tags. That’s why they tend to appear in very specific spots: the neck, armpits, under the breasts, the groin, and along the eyelids. These are all areas where skin folds create constant low-grade irritation throughout the day.
The mechanical process works something like this: persistent friction signals the skin to reinforce itself, prompting fibroblasts (the cells that produce collagen) to proliferate. Over time, the collagen accumulates loosely in a small pocket of dermis, and the overlying skin contracts around it, pushing the growth outward into a protruding tag. Once a skin tag forms, continued friction from clothing, jewelry, or seatbelts can cause it to grow larger, bleed, or become irritated. Necklaces are a particularly common culprit for neck tags, and restrictive or synthetic clothing can worsen tags in skin folds.
Insulin Resistance and Metabolic Factors
Skin tags are one of several visible skin signs linked to insulin resistance. Research dating back to the late 1980s found that 61% of people studied with skin tags also had elevated insulin levels. The connection has been confirmed repeatedly since then, and skin tags are now recognized alongside darkened skin patches (acanthosis nigricans) as a clinical marker that may point to metabolic issues.
The biology behind this link is straightforward. When insulin levels stay chronically high, the excess insulin activates growth factor receptors on skin cells and the connective tissue cells beneath them. This triggers both types of cells to multiply faster than normal. At the same time, high insulin reduces levels of a protein that normally keeps cell growth in check. The result is small, unchecked bursts of tissue growth that show up as skin tags. If you’ve noticed a sudden increase in skin tags, especially in combination with weight gain or darkened patches of skin on your neck or armpits, it may be worth having your blood sugar and insulin levels checked.
Hormonal Changes During Pregnancy
Many people notice new skin tags appearing during pregnancy, particularly in the second and third trimesters. Two factors converge to make this happen. First, rising levels of estrogen and progesterone stimulate the same growth pathways involved in insulin-related tag formation, directly promoting tissue proliferation. Second, as the body changes shape, new areas of skin-on-skin contact develop, especially around the abdomen, under the breasts, and in the groin. The combination of hormonal stimulation and increased friction makes pregnancy one of the most common times for skin tags to appear. Some of these tags shrink or fall off after delivery as hormone levels normalize, though many persist.
Obesity and Body Weight
Obesity is one of the strongest risk factors for developing skin tags, and it amplifies both of the major causes at once. Carrying excess weight creates more and deeper skin folds, which increases friction in areas like the neck, armpits, and thighs. At the same time, obesity is closely tied to insulin resistance, meaning the metabolic growth signals are often elevated too. People with obesity who lose significant weight sometimes find that new skin tags stop appearing, though existing ones typically need to be physically removed.
Genetics and Family History
Some people seem predisposed to developing skin tags regardless of their weight or metabolic health. While skin tags are extremely common in the general population and no single gene has been identified as a universal cause, having multiple family members with skin tags does suggest a hereditary component. In rare cases, a large number of skin tags appearing alongside other unusual skin growths can be associated with inherited genetic conditions. One example is Birt-Hogg-Dubé syndrome, an inherited condition originally described in part by the presence of skin tags, though skin tags alone are far too common to be diagnostic of any syndrome.
When Skin Tags Need Attention
Skin tags are harmless and don’t need to be removed for medical reasons. According to the American Academy of Dermatology, removal is only recommended when a skin tag becomes irritated or bleeds repeatedly, causes pain (especially sudden pain, which can signal the stalk has twisted and cut off blood flow), or develops on an eyelid where it interferes with vision. Tags that constantly catch on jewelry, clothing, or razors fall into the irritation category and are reasonable to have removed by a dermatologist.
The more important reason to pay attention to skin tags is what they might signal about your overall health. A growing cluster of new skin tags, particularly around the neck and armpits, can be an early visible sign of insulin resistance or prediabetes, sometimes appearing years before blood sugar levels become obviously abnormal. If you’re developing them in increasing numbers, the tags themselves are the least of the concern. They’re worth treating as a prompt to look at the bigger metabolic picture.