Why Skin Tags Keep Multiplying on Your Neck and Underarms, and How Laser Removal Actually Works

You've probably felt it while putting on a necklace or shaving your underarms: a tiny bit of loose skin under your fingertip that wasn't there before. It doesn't hurt and it's the same color as the rest of your skin, so it's easy to brush off. Then a few months later, that one has turned into two or three.

That little bump has a name: a skin tag. The medical term is acrochordon, which basically just means a soft, dangling piece of fibrous tissue. There's a real reason they show up almost exclusively on the neck and underarms, and there's an equally real explanation for why lasers can make them disappear for good.

Why do skin tags love the neck and underarms so much?

A skin tag is a small growth that pokes slightly above the surface of the skin, anywhere from smaller than a grain of rice to about the size of a pea, and it's almost always painless.

They tend to show up in the same handful of spots: the neck, underarms, groin, and eyelids. What these areas have in common is that skin folds against skin, or a collar or piece of jewelry rubs against them over and over, several times a day.

A necklace chain brushes the same narrow line on the front of your neck all day long. Every time you move your arm, skin meets skin at the underarm. Compare that to skin tucked under loose clothing that barely moves, and the total amount of friction is on a completely different scale.

That's also why flatter, less mobile spots like the back or calves rarely grow skin tags. In other words, it's not random where they cluster. It comes down directly to how much physical rubbing that particular patch of skin takes on.

How does friction actually turn into a skin tag?

Skin has a built-in defense reflex: when a spot gets irritated repeatedly, it tries to thicken itself up to protect against further damage. Every time a necklace, a bra strap, or a collar rubs the same patch, the cells in the outer layer (the epidermis) keep picking up that irritation signal.

That signal travels down into the dermis, the deeper layer of skin. There, cells called fibroblasts, which produce collagen (the protein fiber that acts like a supporting beam for skin), get switched into overdrive by repeated stimulation. They start pulling small blood vessels and collagen fibers together in one concentrated spot. The result is a tiny bump rising up right there, a skin tag. Think of it like holding a magnifying glass on one point long enough that the surface underneath starts to bulge.

It's a similar process to how a callus forms on your palm. The difference is that the palm is flat, so the thickened skin just spreads out and stays level. But the neck and underarms are folded, so that same thickened tissue has nowhere to spread and pushes upward instead. Same underlying reaction, different result depending on whether the surface is flat or creased: a flat callus in one case, a raised tag in the other.

The key isn't one hard knock, it's a weak, low-grade irritation repeated daily. A single firm press heals quickly. But a mild rub that keeps landing on the same spot for 6 months to 2 years pushes the tissue there into a permanent state of rebuilding itself, and that eventually hardens into a small bump.

Why do skin tags become more common as we age?

Skin is taut when we're young, so there's less folding, and abundant collagen means irritation rarely leaves a lasting mark. As collagen production drops and skin loses elasticity with age, that changes.

Sagging skin means the folds at the neck and underarms deepen, which means more surface area is now rubbing against itself or against clothing. More friction opportunities translate into a higher chance of new skin tags forming. Pregnancy and weight gain, which also increase skin folding, are reported to raise the risk through the same mechanism.

Skin tags also show up more often in people who've gained weight or who have insulin resistance (a state where the hormone that lowers blood sugar isn't working as efficiently as it used to). Extra fullness around the neck means more folds, so a change in body shape becomes just another route to more friction.

That's why skin tags become noticeably more common after middle age than in your twenties. Someone with just one or two on the neck in their younger years often finds them spreading to the underarms and around the eyes later on, and that's really two changes, declining collagen and deepening folds, compounding together.

How can you tell a mole apart from a skin tag?

They can look alike at a glance, but a closer look and a light touch usually settles it. Check for these:

• Smooth surface, apricot to skin-toned color: skin tags are made mostly of fibrous tissue and blood vessels rather than pigment-producing cells, so a deep brown or black color is unusual for them.
• A slight wobble when you pinch it: skin tags hang off the skin by a thin stalk, so they move a little when you grip them, while moles sit flat against the skin and don't budge.
• Size and shape stay the same over time: skin tags usually stay small once they form, while a mole with a jagged border or one that's growing quickly is a sign worth getting checked.

The reason for these differences comes down to what each bump is actually made of. A mole is a cluster of pigment cells sitting under the skin, while a skin tag is fibrous tissue and blood vessels pushed up above it, so the color and the feel are different from the start.

If a growth suddenly darkens or starts changing size quickly, don't assume it's just another skin tag. Get it checked at a clinic.

How does laser removal actually get rid of a skin tag?

The go-to method at most clinics is a CO2 laser. Its light is at a wavelength that water in our bodies absorbs extremely well, so when it hits a skin tag, the water inside boils and evaporates almost instantly. It's the same principle as focusing sunlight through a magnifying glass onto a single point of paper: the energy is concentrated tightly enough to vaporize just the unwanted tissue and nothing else.

An Er:YAG laser works on a similar principle but uses a wavelength that shaves tissue away more shallowly and precisely. Because it transfers less heat to the surrounding tissue, it tends to bleed less, with a healing period of around 5 to 7 days. Both are done under numbing cream, and the procedure itself typically wraps up in 5 to 15 minutes.

Because skin tags tend to form on thin-skinned areas like the neck, even a small amount of extra depth from the laser risks scorching the healthy skin underneath. That's why it matters to have an experienced provider dial in the power and exposure time to match the exact size of each tag.

How does electrocautery differ from laser removal?

Electrocautery uses electricity instead of light. A high-frequency current runs through a fine needle tip, generating heat right at that point, and the heat coagulates the proteins in the tissue to burn away the skin tag. Where a laser converts light energy into heat, electrocautery goes straight to the heat generated by electrical resistance.

When there are several small, shallow skin tags clustered together, electrocautery is often the preferred choice because it can clear multiple tags quickly in one sitting.

For example, if the underarm has a dozen or more tiny, poppy-seed-sized tags packed close together, going through them one by one with electrocautery is usually faster and less uncomfortable overall than treating each one individually with a laser.

Why do skin tags keep coming back even after treatment?

Laser and electrocautery both remove the visible skin tag tissue that's there right now. What they don't touch is the underlying cause: the repeated friction and the age-related loss of skin elasticity that created the tag in the first place.

So if the same habits continue after treatment, a necklace or collar rubbing the same spot day after day, new skin tags can form again in the same area or nearby. Say someone clears five or six tags off their neck in one session; if the shirt collar keeps hitting that same line, it's common to feel a new small bump nearby again 6 to 12 months later. This isn't really the old tag returning. It's closer to a fresh one forming because the same friction conditions are still in place.

What's the right aftercare once the tags are removed?

Cutting down on the friction that caused the tags in the first place goes a long way toward preventing new ones.

• Looser clothing, necklaces, and scarves help reduce friction. Less repeated rubbing on the same spot means fewer chances for a new skin tag to form. Letting a necklace hang a bit looser instead of clasping it tight, or switching to a wider, softer bra style instead of one that digs into the underarm, can noticeably cut down on the irritation that area takes on.
• Sun protection on the treated area matters. Freshly treated skin is more prone to hyperpigmentation (a brownish mark that can linger for a long time), and sun exposure can make that mark last even longer.
• Never try to pull a skin tag off by hand or tie it off with thread. Removing it without proper sterilization can lead to bleeding or infection, so even a tiny tag is safer left to a clinic.

References

Korean Dermatological Association, Ministry of Food and Drug Safety (MFDS), American Academy of Dermatology (AAD), and U.S. Food and Drug Administration (FDA).