Deficiency of one or more of these B vitamins, and tingling, burning or numbness from peripheral neuropathy, including in diabetes, alcohol-related nerve damage, and neuropathy linked to poor diet or long-term medicines.

Each vitamin has its own job in the nerve. Thiamine lets cells turn glucose into usable energy, which nerves depend on heavily. Pyridoxine is needed to make the neurotransmitters that carry signals between them. Vitamin B12 maintains myelin, the insulating sheath that lets a nerve conduct quickly. Replacing what is missing supports repair, though it cannot reverse damage that is already established.

Usually well tolerated. Nausea, stomach upset, headache or a rash occur occasionally, and injections can sting. Vitamin B12 turns the urine a harmless bright colour.

High doses of vitamin B6 taken for months can themselves cause nerve damage with numbness and unsteadiness, so do not exceed the prescribed dose or take extra B6 on top. Folic acid and B12 can mask each other's deficiency, so the cause of any deficiency should be identified rather than assumed. Tell your doctor about kidney disease, or if you take levodopa, which B6 can interfere with.