There are side effects to almost any vitamin if you ingest too much, but there are also side effects if you get too little. Side effects from high levels of B-vitamin, well above the RDA are very rare when taken orally. This is due to the fact that they are water soluble, which allows you to excrete excess amounts through urine. The B vitamins include: B1 (thiamine), B2 (riboflavin), B3 (niacin), B5 (Pantothenic acid), B6 (pyridoxamine), folic acid (B9) and cobalamin (B12). Validated adverse reactions to B vitamins are generally confined to vitamins B3 (niacin), B6 and injections of B1 (thiamine), although rare. These side effects can range from drops in blood pressure, disruption in nerve transmissions to rashes and skin flushing. In order to avoid side effects of B vitamins, make sure you stay within established safe/necessary ranges (see below) - especially when taking vitamins B3 and B6. The goal is to make sure you get proper daily amounts of the necessary B vitamins unless advised otherwise by a qualified physician. This goal is accomplished by taking a daily multivitamin and mineral formula that contains the necessary B vitamins shown below.
• B1: 2-30mg/day
• B2: 5-30mg/day
• B3 (Niacinamide): 30-50mg/day
• B6: 6-50mg/day
• Folic acid: 400-900mcg/day
• B12: 6-50mcg