Medications That Can Cause Numbness

Metformin and Peripheral Neuropathy

Long-term metformin use is associated with biochemical vitamin B12 deficiency that can lead to peripheral neuropathy, especially in patients with anemia or existing neuropathy symptoms 1, 2
The American College of Physicians recommends that patients on long-term metformin therapy should be monitored for vitamin B12 deficiency, as it can cause peripheral neuropathy 1, 2
Metformin use at high doses, such as 2g daily, increases the risk of vitamin B12 deficiency and peripheral neuropathy 2

Metformin-induced neuropathy typically presents as numbness and tingling in a "stocking-glove" distribution (hands and feet) 3, 4
The American Diabetes Association notes that metformin-induced neuropathy can present with impaired vibratory sensation and proprioception 3

Atorvastatin may potentially cause peripheral neuropathy, though this is less common than with metformin 5
The American Heart Association states that atorvastatin is not typically associated with numbness as a common side effect, but high doses may increase the risk 5
Vitamin B12 supplementation at a dose of 2500 mcg daily is protective against neuropathy, not causative 6

The American College of Physicians recommends continuing vitamin B12 supplementation at a dose of 2500 mcg daily to counteract metformin-induced B12 deficiency 2
Neurological assessment is recommended to evaluate small-fiber function, large-fiber function, and protective sensation in patients with metformin-induced neuropathy 3

Diabetic peripheral neuropathy and metformin-induced B12 deficiency neuropathy can present similarly, making diagnosis challenging 3
The American Diabetes Association notes that with adequate vitamin B12 replacement, symptoms of metformin-induced neuropathy may stabilize, but objective findings often do not completely improve 3

The American College of Emergency Physicians recommends seeking immediate medical attention if numbness is accompanied by weakness, severe pain, or rapid progression of symptoms 5
Symptoms of severe B12 deficiency, such as confusion, memory problems, or difficulty walking, require immediate medical attention 6