The majority of pregnant women do not complain of morning sickness until the 6th week of pregnancy, 2 weeks after a missed period. But for some women, that nagging feeling can start as early as one week after conception, a full week before a missed period. Changes in hormones account for the queasiness that occurs.
DRUG CLASS AND MECHANISM: Niacin (nicotinic acid, vitamin B3) is a part of the normal diet that is essential to various chemical reactions in the body.
Niacin (nicotinic acid vitamin), or vitamin B3, is an essential vitamin. Adults require a daily dietary intake of about 15 mg. At much higher doses (1000 to 2000 mg per day) niacin is used as a treatment for high cholesterol.