"You may have heard that too much niacin can be harmful because of
Internet rumors. The rumors falsely state that by taking a large amount
of niacin, people can flush the chemicals that show they've used
marijuana out of their bodies before they take a drug test. No studies
have shown that niacin can do this, and this can be very dangerous
because it may lead to niacin overdose.
Signs and symptoms of a niacin overdose include:
- Rapid heartbeat
- Skin flushing combined with dizziness
- Itching
- Nausea and vomiting
- Abdominal pain
- Diarrhea
- Severe liver damage (hepatoxicity)
If you're concerned about a potential niacin overdose, talk to your
doctor to make sure you're taking the correct amount. If you think you
may have overdosed, seek medical attention immediately."http://www.mayoclinic.com/health/niacin-overdose/an01644
How big are the pills? The maximum recommended dose is 6000mg per day.