Gold Member Badge


  • You're all caught up!

How Much Is Too Much Vitamin B Complex?

author image Karen McCarthy
Karen McCarthy is a health enthusiast with expertise in nutrition, yoga and meditation. She currently studies at the Institute for Integrative Nutrition and has been writing about nutrition since 2012. She is most passionate about veganism and vegetarianism and loves to promote the health benefits of eating fruits and vegetables.
How Much Is Too Much Vitamin B Complex?
Vitamins on a table Photo Credit: redstallion/iStock/Getty Images

Vitamin B complex supplements are a combination of all the B vitamins. These include vitamin B1, or thiamin; vitamin B2, or riboflavin; vitamin B3 or niacin; vitamin B5, or panthothenic acid; vitamin B6, or pyridoxine; vitamin B7, or biotin; vitamin B9, which is folate or folic acid; and vitamin B12, or cobalamin. B vitamins are soluble in water, so excess amounts will not build up in the body, but be excreted through urine. However, large doses of some B-complex vitamins can still cause side effects and health risks.

Video of the Day

Benefits of the Bs

If a blood test shows that you are not deficient in B vitamins, you do not need to supplement with vitamin B complex. If you are deficient, the health risks can be serious. B vitamins are required for basic bodily functions, such as turning food into usable energy and creating red blood cells. Vitamin B complex supplements, taken under the supervision of a doctor, can treat your deficiency and complications associated with it, such as anemia and fatigue.

Signs You May Have Taken Too Much

Some people experience diarrhea, gas and nausea from taking normal doses of vitamin B complex supplements. If you experience excessive itching, hives, swelling, tingling or difficulty breathing, you may be having an allergic reaction and need medical attention. If you've taken too much vitamin B complex, some symptoms you may experience include blurry vision, nausea and vomiting, numbness, high blood sugar, liver problems and skin lesions. Change in urine color to a fluorescent yellow is a normal and harmless side effect of vitamin B complex. If you experience any uncomfortable side effects, see your doctor.

Other Risks

Certain foods are fortified with B vitamins, including breads and cereals. If you're taking tablets that provide 100 percent of your daily recommended intake of B vitamins, you may want to eat fortified foods in moderation -- and watch out for side effects. B vitamins interact with certain medications, so consult with your doctor before taking them if you're on any prescription or over-the-counter medicine.

The Bottom Line

Taking one vitamin B complex tablet a day is not likely to cause toxicity, so you don't have to worry as long as you don't take more than the dosage recommended on the product label. For example, the upper safety limit for vitamin B3 is 35 milligrams daily. If you take a tablet that provides 100 percent of your daily requirement of vitamin B3, which is 16 milligrams, you would be pushing toward the upper limit with 2 tablets. Be sure to see your doctor before choosing a vitamin B complex supplement to make sure it's right for you.

LiveStrong Calorie Tracker
Lose Weight. Feel Great! Change your life with MyPlate by LIVESTRONG.COM
  • Gain 2 pounds per week
  • Gain 1.5 pounds per week
  • Gain 1 pound per week
  • Gain 0.5 pound per week
  • Maintain my current weight
  • Lose 0.5 pound per week
  • Lose 1 pound per week
  • Lose 1.5 pounds per week
  • Lose 2 pounds per week
  • Female
  • Male
ft. in.



Demand Media