The document discusses vitamin B complex supplements and their potential side effects. It begins by explaining that vitamin B is a group of eight water-soluble vitamins that play vital roles in bodily processes. While supplements are generally safe, overdosing can cause side effects like black stools, abdominal pain, and nausea. Each individual B vitamin is then examined in more detail, outlining recommended daily intakes and possible adverse reactions like flushing, diarrhea or allergic responses from high doses. The document stresses consulting a doctor before taking B complex supplements, especially for pregnant/breastfeeding women or those with medical conditions.

1. Vitamin B Complex Supplement Side Effects
The term 'vitamin B family' refers to a group of eight water-soluble vitamins. Initially, vitamin B was
considered to be a single vitamin. However, research studies that were conducted later, revealed
that vitamin B family is composed of eight vitamins called thiamine (vitamin B1), riboflavin (vitamin
B2), niacin (vitamin B3), pantothenic acid (vitamin B5), pyridoxine (vitamin B6), biotin (vitamin B7),
folic acid (vitamin B9), and cyanocobalamin (vitamin B12).
These vitamins are chemically distinct from each other. Each of these vitamins play a vital role in
bodily processes that are integral to the healthy functioning of the human body.
The supplements that contain all the eight B vitamins are referred to as vitamin B-complex. Unlike
fat-soluble vitamins, vitamin B is flushed out of the body through urine.
Though these supplements are believed to have a low potential for toxicity, transient vitamin B
complex side effects may be experienced by a person who takes this supplement in large doses.
Side Effects of Vitamin B Complex Supplements
Vitamin B complex side effects may only be experienced if the supplements are taken in large doses
or doses that are higher than the tolerable upper intake levels. Common side effects (if any) of a
vitamin B-complex overdose include:
? Black stools
? Abdominal pain
? Constipation
? Nausea
? Vomiting
? Change in the color of urine
? Frequent urination
? Diarrhea
? Redness of skin
? Itching
In very rare cases, the use of these supplements could cause allergic reactions, itching and rashes,
or the development of kidney stones. There may be unreported side effects too. In case you
experience side effects that persist, contact your physician immediately.
Side Effects of Individual B Vitamins

2. While the aforementioned side effects are those of vitamin B complex group, given below are the
possible adverse effects of each component of the B-complex supplements. There may be other
unreported side effects. As mentioned above, if any of the adverse effects are unusually severe or
begin to make you feel very uncomfortable, contact your physician immediately.
Thiamine (Vitamin B1)
Side effects are not likely to occur if this vitamin is taken as per the recommended dietary
allowance. Here is the RDA for thiamine based on age. The values for RDA have been developed by
the Food and Nutrition Board of the Institute of Medicine.Daily RDA for Vitamin B1
Group
Age
RDA (mg/day)
Infants
0-6 months
0.2
6-12 months
0.3
Children
1-3 years
0.5
4-8 years
0.6
Males
9-13 years
0.9
14 years and above
1.2
Females
9-13 years

3. 0.9
14-18 years
1
19 years and above
1.1
Pregnant Women
~
1.4
Lactating Women
~
1.4
? The use of thiamine supplements, in very rare cases, may result in an allergic reaction. This may
result in the development of itching, rashes, or hives.
? In case of a severe allergic reaction, the affected individual may experience dizziness, swelling of
the face or tongue, breathing problems, tightness in the chest, or discoloration of the skin.
? Fluid retention, nausea, restlessness, sweating, and weakness are also among the rare side effects
of a thiamine overdose.
Riboflavin (Vitamin B2)
The following table provides information on the recommended dietary allowance for vitamin B2.Daily
RDA for Vitamin B2
Group
Age
RDA (mg/day)
Infants
0-6 months
0.3
6-12 months
0.4

4. Children
1-3 years
0.5
4-8 years
0.6
Males
9-13 years
0.9
14 years and above
1.3
Females
9-13 years
0.9
14-18 years
1
19 years and above
1.1
Pregnant Women
~
1.4
Lactating Women
~
1.6
? A common and harmless side effect of consuming riboflavin is that it turns the urine into a
yellowish-orange color.
? An overdose may increase frequency of urination and diarrhea.

5. ? If a person is allergic to any of the ingredients of the supplement, he/she may develop an allergic
reaction which may result in hives, breathing problems, and swelling of the face, lips, tongue, and
throat.
Niacin (Vitamin B3)
Side effects are less likely to occur if the vitamin supplement is taken as per the recommended
dietary allowance.Daily RDA for Vitamin B3
Group
Age
RDA (mg/day)
Infants
0-6 months
2
6-12 months
4
Children
1-3 years
6
4-8 years
8
Males
9-13 years
12
14 years and above
16
Females
9-13 years
12

6. 14 years and above
14
Pregnant Women
~
18
Lactating Women
~
17
? Niacin may cause flushing of the skin, which could last for a few hours. Along with flushing of the
skin, the affected individual could experience redness, tingling or burning sensation, sweating, or
chills within 4 hours of taking the supplement.
? Other side effects include dizziness, diarrhea, stomach upset, nausea and vomiting, and heartburn.
? In very serious cases, the affected individual may experience irregular heartbeat, persistent
headache, joint pain, swelling of arms or legs, and blurred vision.
? Other serious but rare side effects include bloody or black stools, intense abdominal pain,
incessant nausea and vomiting, muscle and joint pain, and yellowing of the eyes.
? If a person develops an allergic reaction, he/she may develop hives, itching, and swelling of the
face, lips, tongue, or throat.
Pantothenic Acid (Vitamin B5)
Adverse effects rarely occur if vitamin B5 is taken as per the RDA. Note that the therapeutic range
for all the individual B vitamins may be higher than the RDA.Daily RDA for Vitamin B5
Group
Age
RDA (mg/day)
Infants
0-6 months
1.7
6-12 months
1.8

7. Children
1-3 years
2
4-8 years
3
Males
9-13 years
4
14 years and above
5
Females
9-13 years
4
14 years and above
5
Pregnant Women
~
6
Lactating Women
~
7
? In case of an overdose, the affected individual may suffer from diarrhea.
? In rare cases, an allergic reaction could occur, which may result in hives, itching, swelling of face,
lips, tongue, or throat, trouble breathing, and tightness in chest.
Pyridoxine (Vitamin B6)
Here is the recommended dietary allowance for vitamin B6. The body's need for vitamin B6 can be
met if the dietary sources or supplements are taken as per the RDA.Daily RDA for Vitamin B6

8. Group
Age
RDA (mg/day)
Infants
0-6 months
0.1
6-12 months
0.4
Children
1-3 years
0.5
4-8 years
0.6
Males
9-13 years
1
14-18 years
1.3
19-50 years
1.3
51 years and above
1.7
Females
9-13 years
1
14-18 years

9. 1.2
19-50 years
1.3
51 years and above
1.5
Pregnant Women
~
1.9
Lactating Women
~
2
? In most people, the use of vitamin B6 supplements will not cause any adverse effects, if these are
taken as per the prescribed dosage. However, some people may develop stomach pain, tingling,
drowsiness, headache, nausea, vomiting, and loss of appetite.
? Intake of this vitamin in large doses is known to increase the risk of brain and nerve problems.
? Some people may experience allergic reactions that include development of hives, swelling of face,
lips, tongue, or throat, and breathing problems.
? In rare cases, one may feel disoriented, resulting in poor coordination. The affected individual may
experience numbness or reduced sensation in different body parts, particularly feet and hands which
may further lead to poor coordination. Extreme fatigue is also a serious side effect of an overdose of
this vitamin.
Biotin (Vitamin B7)
There are no reports on toxicity of vitamin B7, but it would be best if this vitamin is taken as per the
RDA.Daily RDA for Vitamin B7
Group
Age
RDA (mcg/day)
Infants
0-6 months

10. 5
6-12 months
6
Children
1-3 years
8
4-8 years
12
Males
9-13 years
20
14-18 years
25
19-50 years
30
51 years and above
30
Females
9-13 years
20
14-18 years
25
19-50 years
30
51 years and above
30

11. Pregnant Women
~
30
Lactating Women
~
35
? There is a lack of evidence on the side effects of a biotin overdose and there are no reports on
toxicity.
? In a study that was conducted on pregnant rats, administration of large doses of biotin caused the
placenta to shrink. This made them susceptible to miscarriage. However, a link between biotin
overdose and miscarriage in pregnant women cannot be drawn on the basis of animal studies.
Folic Acid (Vitamin B9)
If taken as per the recommended doses, folic acid does not cause any side effects. Here is the daily
RDA for folic acid based on age.Daily RDA for Vitamin B9
Group
Age
RDA (mcg/day)
Infants
0-6 months
65
6-12 months
80
Children
1-3 years
150
4-8 years
200
Males

12. 9-13 years
300
14 years and above
400
Females
9-13 years
300
14 years and above
400
Pregnant Women
~
600
Lactating Women
~
500
? Research suggests that an overdose of this vitamin may increase the risk of heart attack in those
who already have heart problems. In another study, it has been found that the risk of lung cancer or
prostate cancer may also increase.
? If a person is allergic to the ingredients of the supplement, he/she may develop an allergic reaction
resulting in rash, hives, swelling of the face, lips or tongue, dizziness, and tightness in the chest.
Cyanocobalamin (Vitamin B12)
Though the tolerable upper intake level has not been established, it would be best to take vitamin
B12 as per the RDA.Daily RDA for Vitamin B12
Group
Age
RDA (mcg/day)
Infants
0-6 months

13. 0.4
6-12 months
0.5
Children
1-10 years
0.7-2
Males
11 years and above
2.4
Females
11 years and above
2.4
Pregnant Women
~
2.6
Lactating Women
~
2.8
? While it is safe for most people, in some cases this vitamin may cause side effects in the form of
diarrhea, itching, and blood clots.
? Severe allergic reactions may cause hives, breathing problems, cramping due to muscle weakness,
fever and chills, swelling of the body, swelling of the face, lips or tongue, chest pain, bleeding, or
bruising.
Things to Consider Before Taking Vitamin B Complex
Before taking B complex supplements, it is advisable to consult your health care provider to find out
if you need to take vitamin B-complex supplements or not. It would be best not to consume these
supplements without consultation, especially under the following circumstances:
? Women who are pregnant or breastfeeding must consult a doctor to know if they need to take
vitamin B. These supplements must be taken as per the prescribed dosage.

14. ? Do inform your doctor if you have a history of stomach ulcer, diabetes, liver problems, or gout.
? Inform your doctor if you are taking other medicines, so as to prevent adverse drug interactions.
? Inform your doctor if you suffer from a drug allergy.
Though the use of vitamin supplements can prove beneficial for those who suffer from a vitamin B
deficiency, do seek medical help if you experience any of the aforementioned vitamin B complex side
effects. You must also try to follow a healthy diet and make the necessary lifestyle changes. It would
be best to include the dietary sources of vitamin B in your diet rather than taking vitamin
supplements.
Disclaimer: This Buzzle article is for informative purposes only and does not, in any way, intend to
replace the advice of a medical expert.
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