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Vitamin B complex is a collection of water-soluble vitamins, whose presence is necessary for proper growth, development and cell metabolism in general. There are a total of 8 vitamins, that make up the complex. Vitamin B complex members are commonly found in unprocessed fruits and vegetables. Fish, chicken and eggs are also sources of Vitamin B, but those on a vegetarian diet, get the most content. An exception is B12, which is found only in animal products and milk, so vegetarians are at risk of a deficiency.

A deficiency in any of the vitamin B complex members can cause varied diseases, depending on the lack of that complex member. For e.g. Vitamin B3 deficiency can cause pellagra. Vitamin B7 is necessary for infant growth and nervous system development. The benefits of vitamin B complex, on the health of an individual is multiple and manifold. But can you take too much vitamin B? And if so, what are the symptoms of too much vitamin B complex?

Vitamin B Complex Dosage

Too much of Vitamin B complex can cause side effects. But too little can cause a deficiency. To ensure you get the right amount, without overdoing, learn how much is too much Vitamin B, and make sure you stay under the limit. Below is a table with the recommended daily allowance (RDA) for vitamin B complex members:

Name RDA Special Cases
Vitamin B1 (thiamine) 200 mcg - 1.5 mg Pregnant & Lactating 1.4 mg
Vitamin B2 (riboflavin) 1.7 mg Infants 0.4 mg Pregnant 1.4 mg
Vitamin B3 (niacin) Up to 35 mg Infants 2 mg Pregnant 18 mg
Vitamin B5 (pantothenic acid) 5 mg Infants 1.7 mg Pregnant 7 mg
Vitamin B6 (pyridoxine) Up to 100 mg Infants 100 mg Lactating 2 mg
Vitamin B7 (biotin) 35 mcg NA
Vitamin B9 (folic acid) 400 mcg Infants 65 mcg Pregnant 600 mcg
Vitamin B12 (cobalamins) 2.4 mcg Infants 0.4 mcg Lactating 2.8 mcg

Too Much Vitamin B Complex Side Effects

The following symptoms are rare, and their occurrence is mainly due to taking a certain B complex vitamin, alone, and in large quantities. For example, a high intake of Vitamin B-6 (pyridoxine) alone, and no other Vitamin B member. Vitamin B complex members work best, when they are together, on their own if they accumulate, the following symptoms can occur.

Vitamin B1 (Thiamine)
  • Upset stomach
  • High blood pressure
  • Heart palpitations
  • Insomnia and agitation
Vitamin B2 (Riboflavin)
  • Increase in urine production
  • Urine can turn bright yellow or orange
  • Diarrhea
  • Nausea and vomiting
  • Anemia
Vitamin B3 (Niacin)
  • Blurred vision
  • Jaundice
  • Skin rashes and sweating
  • Redness and itching, with throbbing headaches
  • Nausea and vomiting
  • Lowers blood pressure
  • Interferes with glucose levels in the body
  • Elevated liver enzymes
  • Liver inflammation
  • Joint pains
  • Worsens gout
  • Aggravates ulcers, with increase in production of stomach acid
Vitamin B5 (Pantothenic acid)
  • Upset stomach and diarrhea
  • Dehydration
  • Severe fatigue
  • Edema
  • Reduced protein metabolism
Vitamin B6 (Pyridoxine)
  • Feeling of heaviness
  • Trouble in movement
  • Tingling sensations
  • Muscle cramps and spasms
  • Mood problems and depression
  • Decrease in estrogen
  • Drastic changes in blood pressure
  • Heart palpitations
  • Numbness in the limbs
  • Nerve toxicity
  • Liver inflammation
  • Bloating and nausea
  • Vomiting
  • Headaches
  • Loss of appetite and fatigue
  • Skin allergies and acne
  • Stomach pain
  • Insomnia
Vitamin B7 (Biotin)
  • Decrease in insulin release rate
  • Increase in blood sugar
Vitamin B9 (Folic acid)
  • Those with a history of seizures, should not take extra supplements of this vitamin, as it can trigger a seizure
  • It interferes with B12 levels in the body, and can cause a deficiency
  • Bloating of the abdomen
  • Loss of appetite and nausea
Vitamin B12 (Cobalamin)
  • Rashes
  • Numbness on right side of body
  • Heart palpitations
  • Insomnia
The below groups should be cautious, with Vitamin B complex supplements:
  • Those who are trying to conceive
  • Lactating mothers and pregnant women
  • People with stomach ulcers
  • Those suffering from gout, diabetes, liver disease and gallbladder disease
  • Those with a history of medical allergies
  • People who use over-the-counter medicines, herbal or alternative medicines
  • Those with heart and blood pressure problems
  • Recent heart attack patients
The symptoms of too much vitamin B complex, may appear frightening, but there is a much higher risk, that you could have a deficiency of vitamin B than excess. Those who obtain their vitamin B amount from food directly, have little or no risk of toxicity. In fact, if you follow a proper balanced diet, like plenty of green leafy veggies and meats, then your levels are sufficient, not too much or too little. The risk of vitamin B overdosing, is in taking supplements and pills to get your nutrient intake. While supplements are beneficial, care and caution must be exercised, to make sure you don't OVERDO it. Vitamin B12 supplements might be necessary for vegetarians, since vegetables do not contain this member. Before taking any supplements, consult a physician, talk about your medical history and issues, then purchase vitamins on his/hers recommendation. Do not be your own doctor, or listen to others opinions on the subject of supplements.