A skin tag is a small outgrowth of normal skin tissue, built from an outer shell of epidermis wrapped around a core of loose connective tissue, collagen fibers, and blood vessels. There is nothing exotic or dangerous in a skin tag; it is assembled from the same ingredients as the skin around it, just arranged differently. The structure is straightforward, but the details of what goes on inside one reveal quite a bit about why skin tags form, why they are almost always painless, and why they occasionally cause trouble.
The Epidermal Shell
The outermost layer of a skin tag is epidermis, the same type of tissue that covers the rest of your body. Under a microscope, though, this epidermis looks different from the surrounding skin. Researchers examining skin tag samples consistently find that the epidermal layer is thickened and overgrown. The surface may show excess keratin buildup, and the rete ridges (the finger-like projections where the epidermis meets the tissue underneath) tend to be elongated and sometimes wavy. One histological study described the epidermis of skin tags as showing hyperplasia, papillomatosis, hyperkeratosis, and acanthosis, all of which are simply different flavors of “thicker and more textured than normal.”1PubMed Central. Skin Tags: A Link Between Lesional Mast Cell Count/Tryptase Expression and Obesity and Dyslipidemia This thickened outer shell is part of what gives a skin tag its fleshy, somewhat rubbery texture when you pinch it.
Despite the overgrowth, the epidermis of a skin tag is benign. It does not show the disordered, atypical cell growth seen in precancerous or cancerous lesions. The cells are normal keratinocytes behaving normally; there are just more of them stacked up than you would find in flat, unstretched skin.
The Connective Tissue Core
Underneath the epidermal shell sits the real bulk of the skin tag: a core of loose connective tissue dominated by collagen fibers. This is the same type of structural protein that gives skin its strength elsewhere on the body. In a skin tag, the collagen is loosely arranged rather than tightly packed, giving the growth its soft, pliable feel. Scattered among the collagen fibers are fibroblasts, the cells responsible for producing and maintaining that collagen scaffold.
One distinctive feature of skin tag tissue is a noticeable reduction in elastic fibers. Elastic fibers are the stretchy components that let skin snap back after being pulled. A study using specialized staining found moderate to marked thinning of elastic fibers across all skin tag specimens examined, with most cases also showing a reduced number of these fibers compared to normal surrounding skin.2International Journal of Pathology and Clinical Research. Reduced and Thinned Elastic Fibers in Skin Tag This loss of elastic fiber likely contributes to the skin tag’s tendency to hang loosely rather than sit flat against the body. Without that elastic scaffolding pulling the tissue taut, the growth can droop on its narrow stalk.
Some larger skin tags also contain fat cells (adipocytes) within the connective tissue core. The presence of fat is more common in bigger growths and helps explain why particularly large skin tags can feel soft and doughy rather than firm.
Blood Vessels and the Stalk
Every skin tag has at least a small blood supply. Tiny blood vessels run up through the stalk (the narrow base that attaches the skin tag to the body) and branch into the growth itself. These vessels are thin-walled capillaries and small venules. In most cases, the blood supply is modest, which is why small skin tags can be snipped off with minimal bleeding.
The stalk is structurally important. It is the narrowest part of the growth, and it contains the blood vessels, connective tissue, and epidermal covering that connect the skin tag to the rest of the body. The stalk is also the weak point: because the blood supply is funneled through such a narrow passage, anything that compresses or twists the stalk can cut off circulation to the growth. When that happens, the results can be dramatic, but more on that below.
Why Skin Tags Rarely Hurt
Most people notice skin tags because they catch on clothing or jewelry, not because the tags themselves cause pain. There is a structural reason for this. Research has found that skin tags typically do not contain cutaneous nerves.3Archives of Dermatology. Skin Tags Do Not Contain Cutaneous Nerves The surrounding skin at the base has normal nerve endings, which is why tugging on a skin tag or twisting it can feel uncomfortable. But the tag itself, the dangling bit of tissue, is essentially a nerve-free zone.
This explains why many people can snip off a small skin tag and feel very little beyond the initial pinch at the base. It also means that skin tags are not sensory organs in any meaningful way. They do not itch on their own (though the friction they cause against surrounding skin can produce irritation), and they do not register temperature or pressure independently.
Mast Cells Inside the Growth
One finding that has attracted research interest is the presence of mast cells in the dermal layer of skin tags. Mast cells are immune cells that release chemical signals involved in inflammation and allergic responses. The same study that described the thickened epidermis also noted upper dermal inflammatory infiltrate containing mast cells.1PubMed Central. Skin Tags: A Link Between Lesional Mast Cell Count/Tryptase Expression and Obesity and Dyslipidemia The researchers explored connections between mast cell density in skin tags and conditions like obesity and abnormal blood lipids.
The exact role of these mast cells is still being worked out. They may be responding to chronic low-grade irritation at the skin surface, or they may be involved in the tissue remodeling that causes the skin tag to form and grow in the first place. Either way, their presence is a reminder that a skin tag is not just inert tissue hanging off the body. It contains active cells capable of participating in immune signaling.
What Makes Skin Tags Grow
Knowing what a skin tag is made of naturally raises the question of what causes that tissue to pile up in the first place. The answer involves several overlapping factors, and the relative contribution of each varies from person to person.
Friction and Mechanical Irritation
Skin tags overwhelmingly appear in areas where skin rubs against skin or clothing: the neck, armpits, groin folds, under the breasts, and along the eyelids. This distribution pattern strongly suggests that friction is a trigger. One case report described a patient who developed multiple skin tags arranged in a linear pattern along a line of habitual friction, providing especially clear evidence that repetitive rubbing can stimulate skin tag formation.4PubMed. Friction induced skin tags The mechanism likely involves chronic low-level irritation prompting fibroblasts and keratinocytes to proliferate and eventually produce the characteristic outgrowth.
Growth Factor Signaling
Insulin-like growth factor 1 (IGF-1) appears to play a meaningful role in skin tag development. One study found significantly higher levels of IGF-1 activity in both the epidermal and dermal layers of excised skin tags compared to normal control skin, with fibroblasts and endothelial cells in the tags showing elevated IGF-1 receptor expression. Certain genetic variants in the IGF-1 gene were also more common in patients with skin tags, and those variants were linked to developing multiple skin tags rather than just one or two.5PubMed Central. Role of insulin-like growth factor-1 in skin tags: a clinical, genetic and immunohistochemical study in a sample of Egyptian patients
A separate study confirmed this picture by looking at IGF receptors specifically. Skin tag tissue showed significantly higher expression of both IGF-1 and IGF-2 receptors compared to controls, and increases in serum insulin, serum IGF-1, and insulin resistance scores were all associated with higher receptor expression in the tissue.6PubMed Central. The role of insulin-like growth factor in Acrochordon Etiopathology This connection between insulin, IGF-1, and skin tag growth helps explain why skin tags are more common in people with insulin resistance, type 2 diabetes, and obesity. The growth factor environment in those conditions essentially gives skin cells a stronger signal to proliferate.
Human Papillomavirus
A more surprising component sometimes found inside skin tags is HPV DNA. This does not mean skin tags are warts (they are structurally different), but HPV may play a supporting role in some cases. One study detected HPV DNA (types 6 and 11, which are low-risk strains associated with benign growths) in about half of the skin tag samples tested, while surrounding normal skin tested negative.7PubMed. Human papillomavirus and skin tags: Is there any association? Another study using similar methods found HPV 6/11 DNA in an even higher proportion of samples.8PubMed. The detection of human papillomavirus DNA in skin tags
The detection rates vary widely between studies, which suggests that HPV is probably not a universal cause of skin tags but may contribute to their development in a subset of cases. The virus could promote the same kind of epidermal overgrowth seen in warts, but in the context of skin tags, the growth pattern produces a soft, pendulous polyp rather than a rough, flat wart. Whether HPV is an active driver or just a bystander virus that colonizes already-formed tags is still debated.
Skin Tags and Metabolic Health
Because insulin and IGF-1 are so closely tied to skin tag growth at the cellular level, skin tags have attracted attention as possible outward markers of metabolic problems. Several studies have investigated whether having skin tags predicts conditions like metabolic syndrome, elevated blood lipids, or cardiovascular risk factors.
One study found that the percentage of patients with metabolic syndrome was substantially higher among those with skin tags than among controls without skin tags. The same study identified the presence of skin tags as an independent factor associated with elevated homocysteine and endothelin-1 levels, both of which are markers related to cardiovascular risk.9PubMed Central. The Evaluation of the Impact of Age, Skin Tags, Metabolic Syndrome, Body Mass Index, and Smoking on Homocysteine, Endothelin-1, High-sensitive C-reactive Protein, and on the Heart However, another study using multivariate analysis found no significant association between the number of skin tags and the individual components of metabolic syndrome once other variables were accounted for.10PubMed Central. Association of Skin Tag with Metabolic Syndrome and its Components: A Case–control Study from Eastern India
The picture, in short, is mixed. Having many skin tags, especially if they appeared relatively quickly, is worth mentioning to a doctor during a routine checkup. But a few skin tags on the neck do not by themselves mean anything alarming about your blood sugar or heart health. They are common enough in the general population that most cases are unrelated to any systemic disease.
When a Skin Tag Turns Dark
Occasionally, a skin tag will suddenly change color, turning dark brown, purple, or black. This is usually alarming to see but is almost always caused by something mundane: torsion. When the narrow stalk twists, the blood supply gets pinched off. Without incoming blood, the tissue dies. The skin tag undergoes ischemic necrosis, producing acute inflammation and the characteristic darkening.11Actas Dermo-Sifiliográficas. Infarcted Giant Skin Tag
An infarcted skin tag can be tender and swollen at the base, and it may eventually fall off on its own as the dead tissue separates. In clinical practice, doctors sometimes encounter these and need to distinguish them from melanoma or other pigmented skin lesions, since a darkened lump of tissue on the skin understandably raises concern. The key clue is usually the stalk: a twisted, inflamed peduncle connected to a suddenly darkened growth is the hallmark of skin tag torsion rather than a malignant process. Still, any sudden color change in a skin growth warrants a professional look.
How Structure Guides Removal
The structure of a skin tag directly determines how it is best removed. Because the growth hangs from a narrow stalk with a small blood supply and no nerve fibers inside the tag itself, snipping the stalk with scissors is a remarkably straightforward procedure. A randomized trial comparing scissor excision to laser treatment for skin tags on the neck and armpits found that scissor snipping produced a higher complete healing rate at twelve weeks, lower pain scores, and greater patient satisfaction. Roughly two-thirds of patients preferred scissors for future treatments.12PubMed. Removal of skin tags: scissor excision versus non-ablative 532nm-LBO-laser in a randomized intraindividual controlled observer-blinded clinical trial
The laser had its advantages: it was faster and bloodless, and required no wound dressing. But the treated tags stayed attached as necrotic tissue for up to three weeks before falling off, and the laser-treated sites had higher rates of redness and pigmentation changes. Scissor excision, by contrast, removes the entire structure immediately. Once the stalk is cut, the epidermis at the base heals the way any small wound does, and the tag is gone.
Cryotherapy (freezing) and electrocautery (burning) are other common approaches that work by destroying the tissue in place. Both can cause pigment changes in the surrounding skin, which makes them less ideal for cosmetically sensitive areas like the neck and face. The choice between methods comes down to the size and location of the tag, patient preference, and what equipment is available.
Skin Tags in Rare Genetic Conditions
For most people, skin tags are a minor cosmetic nuisance with no deeper medical significance. But in rare cases, frequent or widespread skin tags can be a feature of a genetic syndrome. Birt-Hogg-Dubé syndrome, caused by mutations in the folliculin gene on chromosome 17, is one such condition. It is inherited in an autosomal-dominant pattern and presents with small benign growths of the hair follicle, along with skin tags, typically clustered on the face, neck, and upper trunk.13PubMed Central. Birt–Hogg–Dubé Syndrome: A Rare Genodermatosis Presenting as Skin Papillomas Beyond the skin findings, the syndrome carries risks for lung cysts, spontaneous collapsed lung, and certain kidney tumors, making it important to identify even though it is uncommon.
The skin tags in Birt-Hogg-Dubé syndrome are structurally similar to ordinary skin tags under a microscope. What sets them apart clinically is the pattern: if you have dozens of soft growths concentrated on the face and upper body, especially with a family history of similar skin findings or lung problems, a genetic evaluation could be worthwhile. For the vast majority of people with a handful of skin tags in friction-prone areas, however, this kind of workup is unnecessary.