Can You Overdose On Vitamin B?

It is possible to overdose on vitamin B. Some of the B vitamins are more toxic than others and some prove more prone to misuse. Some drug users, for example, suffer severe side effects when they take large doses of vitamin B-3 in attempts to foil the results of urine screening tests. Some medical reasons exist for taking large amounts of some B vitamins, but these uses also pose health risks. Talk to your doctor before taking vitamin B in doses beyond their recommended daily allowance.

Vitamin B-3 Overdose

In 2005, poison control centers around the U.S. logged an unusually high number of calls -- more than 3,100 -- from people who had taken vitamin B-3 for non-medical reasons, including efforts to pass drug-screening tests. Symptoms, some of which required medical care, included nausea, rapid heartbeat, vomiting and rashes. Callers reported taking up to 8,000 mg of niacin -- 500 times the recommended daily allowance. Majoj Mittal, an emergency room doctor at Children's Hospital in Philadelphia, notes that one overdose of vitamin B-3 was so severe that the patient required a liver transplant, according to his report in an April 2007 issue of "Annals of Emergency Medicine."

Brain and Nerve Damage

If you take an overdose or vitamin B-6, also called pyridoxine, you might face side effect such as sleepiness, vomiting, stomach pain, tingling and loss of appetite. If you take high doses of vitamin B-6 for a long time, more serious side effects include nerve and brain problems. Medical reasons that may make it appropriate to take high doses of vitamin B-6 include vitamin B-6 deficiency, anemia and reducing levels of homocysteine, an enzyme connected to heart disease. You might also find vitamin B-6 helpful for treating premenstrual syndrome and pregnancy-related nausea. But, because of the potential for serious side effects, you should talk to your doctor before taking vitamin B-6 in amounts higher than the RDA.

Lesser Side Effects

Overdoses of some B vitamins pose fairly minor side effects. If you take too much vitamin B-2, also known as riboflavin, your urine output may increase and may turn orange. High doses of vitamin B-2 could also give you diarrhea. Thiamine -- vitamin B-1 -- poses rare allergic reactions and skin irritations but is usually safe when taken in appropriate amounts. Vitamin B-5 -- pantothenic acid -- may cause diarrhea if you take an overdose. If you have hemophilia, you could suffer more serious problems -- vitamin B-5 could make it harder to control bleeding.

Considerations

Most people get enough vitamin B in their diets. You may not need to take any vitamin B -- let alone enough to cause symptoms of an overdose -- if you regularly consume meat, poultry, fish, eggs and dairy products. You can also find some of the B vitamins in plant foods -- nuts, beans and whole grains -- but vegans may not get enough vitamin B-12 from their diets. Older adults may also benefit from vitamin B-12 supplements. If you drink excessive amounts of alcohol, you may also need supplements of some B vitamins. Talk to your doctor about whether supplements of any B vitamins might help you and seek immediate medical treatment if you take an overdose.