Vitamin B1- none reported.

Vitamin B2- none reported.

Vitamin B3- Lovastatin- coadmin of niacin may result in rhabdomysis - one report Sulfinpyrazones uricosuric effect may be inhibited.

Vitamin B5- none reported.

Vitamin B6- levodopa- pyridoxine reduces levodopas effectiveness.

With Phenobarbital- phenobarbital serum levels may be decreased.

With Phenytoin- phenytoin serum levels may be decreased.

Drug/lab test interactions:

Vitamin B3- decreased glucose tolerance,abnormalities of hepatic function tests,hyperuremia.

Vitamin B1- feeling of warmth, pruritus, urticaria, weakness, sweating, restlessness, tightness of throat, angioneurotic edema, cyanosis, pulmonary oedema, haemorrhage into GI tract, cardiovascular collapse, death. Some tenderness and induration may follow IM use.

Vitamin B2- none reported.

Vitamin B3- flushing,pruritus, GI distress appear frequently with nicotinic acid oral therapy. Activation of peptic ulcer, nausea, vomiting, abdominal pain, diarhoea. Severe generalised flushing, sensation of warmth, keratosis nigricans, pruritus, skin rash, dry skin, tingling. Toxic ambyopia, hypotension, transient headache, artial fibrillation and other cardiac arrhythmias.

Vitamin B5- none reported.

Vitamin B6- sensory neuropathic syndromes, unstable gait, numg feet, awkwardness of hands, perioral numbness, decreased sensation to touch, temperature and vibration, parathesia, somnolence, low serum folic acid levels.

Vitamin B1- thiamine hcl.- hypersensitivity to thiamine

Vitamin B2- Riboflavin- none reported. Vitamin B5- Calcium patothenate- none reported.

Vitamin B3- Nicotinic acid- hepatic dysfunction, active peptic ulcer.

Vitamin B6- Pyridoxine- hypersensitivity to pyridoxine.

Special precautions:

Vitamin B1- sensitivity reactions can occur. Deaths have resulted from IV use. An interdermal test dose is recommended in patients with suspected sensitivity.

Risks to fetal abnormalities reported, use during only if clearly needed. Use with caution in nursing women.

Vitamin B2- Ribloflavin deficiency seldom occurs alone, often associated with B vitamins. May cause yellow/orange discolouration of urine.

Vitamin B3- schizophrenia- no convincing evidence to support megadoses of nicotinic acid in the treatment of schiziphrenzia. High doses are associated with considerable toxicity. Use doses in excess of nutritional requirements during pregnancy and lactation only when clearly needed and when the potential benefits outweigh the potential hazards to the fetus or nursing infant.

Vitamin B6- pregnancy and lactation- pyridoxine requirements are increased during pregnancy and lactation. Pyridoxine varies in concentration in breast milk in response to changes in maternal intake of the vitamin. Admininster high doses with caution.