Is it OK to Take a B-Complex Vitamin Along With a Multivitamin Daily?

Taking daily vitamins is a healthy habit to form; however, taking more than you need could lead to trouble. If you take high doses of some B vitamins, you could face serious side effects, including increased risk of heart disease, stroke, stomach ulcers and liver damage. Ask your doctor if you need to take a multivitamin, a vitamin B complex supplement or both.

Recommended Doses

To find out if you can safely combine multivitamins and vitamin B complex supplements, add the totals of the doses of vitamin B in both supplements. Here are the recommended daily allowances, or RDA, for the B vitamins most commonly used in B complex formulas: vitamin B-1, 1.1 mg to 1.5 mg; vitamin B-2, 1.1 mg to 1.6 mg; vitamin B-3, 14 mg to 17 mg; vitamin B-5, 5 mg to 7 mg; vitamin B-6, 1.3 mg to 2.0 mg; vitamin B-12, 2.4 mg to 2.8 mg. In general, men need more vitamin B than women, but pregnant and breastfeeding women as well as older adults also might need higher amounts.

Some Benefits of Higher Doses

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Taking a multivitamin plus vitamin B complex that increases your intake of vitamin B beyond the RDA might prove prudent, but ask your doctor first. Reasons to take extra vitamin B-1 include thiamine deficiency, prevention of cataracts and to alleviate symptoms of alcohol withdrawal. Doctors might prescribe niacin, or vitamin B-3, in amounts up to 4 g a day to treat high cholesterol or prevent heart disease in people with high cholesterol. Other reasons to take niacin include slowing the progression of Alzheimer's disease and delaying the progression of Type 1 diabetes. You can take up to 10 mg of vitamin B-5 daily as a supplement. Vitamin B-6 in doses higher than the RDA can treat B-6 deficiency, premenstrual syndrome, kidney disease and prevent a vision problem called macular degeneration.

Insufficient Evidence

Popular reasons for taking vitamin B complex supplements with or without multivitamins include efforts to increase athletic performance, improve mood, pass drug screening tests and improve orgasm. The long list of other possible uses for vitamin B complex includes treating AIDS, attention-deficit hyperactivity disorder, alcoholism and acne. Evidence for such uses ranges from insufficient to nonexistent. Don’t take vitamin B based on anecdotes from friends or rumors on the Internet. Taking too much vitamin B can prove toxic.

Risks

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Don’t take vitamin B complex supplements and multivitamins without consulting a medical professional and don’t exceed dose recommendations unless a doctor specifically recommends that you do so. Long-term use of some B vitamins can cause vision loss and nerve damage and worsen kidney and liver disease. Short-term use of some B vitamins in high doses also can put your health in jeopardy. In 2005, for instance, more than 3,000 people in the United States who took niacin in high doses contacted poison control centers with symptoms of serious overdose.