Formication in menopause: the sensation of insects crawling on skin

What it feels like

Crawling, tingling, prickling or the distinct sense of something moving across or just beneath the skin, with nothing visible and nothing there.

It commonly affects the arms, legs, scalp and torso, tends to be worse at night and when still, and often arrives alongside or just before a hot flash.

It is unsettling in a specific way, because the brain interprets it as an external cause. Many people check their skin repeatedly before accepting there is nothing on it, and a number do not mention it for fear of how it sounds.

What is thought to cause it

The evidence here is thinner than for hot flashes and this page will not overstate it.

The leading explanation is that estrogen influences the function of peripheral sensory nerves, and its decline produces aberrant firing interpreted as touch. The close association with hot flashes suggests a shared origin in the autonomic and hypothalamic changes underlying vasomotor symptoms.

A contributing factor is more concrete: skin becomes drier and the barrier weaker after menopause, and dry skin is itself more prone to itching and abnormal sensation.

What else causes it

Formication has a well-described differential and several items on it are common, treatable and easily missed:

• Vitamin B12 deficiency, a classic cause of abnormal skin sensation, and more common with age and with long-term acid-suppressing or metformin use
• Thyroid disease, in either direction
• Diabetes and prediabetes, through small fibre neuropathy
• Iron deficiency, which also causes restless legs
• Medication effects and withdrawal, including from alcohol, opioids and stimulants
• Anxiety states, which amplify bodily sensation generally
• Actual skin conditions including scabies and eczema, which is why an examination is part of the assessment

What helps

There is no specific treatment, because there is no established mechanism to target. What is reported is that it often improves when vasomotor symptoms are treated, consistent with their close association.

Practical measures worth trying: consistent emollient use, since dry skin amplifies it; avoiding hot water and soap-based cleansers; keeping the bedroom cool, since it is typically worse at night and worse when overheated.

As with the electric shock sensations covered elsewhere, a substantial part of the burden is fear of what it means. Knowing it is a documented and benign menopausal symptom does real work on its own.

When to see someone

Ask for vitamin B12, ferritin, thyroid function and HbA1c if it persists. That panel is cheap and covers most of the treatable alternatives.

See someone promptly if there is numbness or weakness alongside it, if it follows a specific nerve distribution, if there is a visible rash, or if it is accompanied by problems with balance or walking.