“What causes skin tags in armpits?”

Genetics is the cause of skin tags. They usually show up in folds of the skin, such as around the eyes, around the neck, under the arms, and in the groin. Removing some does nothing to prevent new ones from appearing, which they almost inevitably do with time. Fortunately, they are quite easy and pretty quick and nearly painless for a dermatologist to remove. A dozen can be removed in a couple of minutes in experienced hands.