Vitamin B complex: side effects, limits, and who should be cautious
The essentials at a glance
Most B vitamins have no established upper limit. Three do: vitamin B6, niacin, and folic acid. In 2023, the European Food Safety Authority (EFSA) set an upper limit of 12 milligrams per day for adults for vitamin B6; previously, it was 25. The critical issue is nerve damage in the hands and feet.
Water-soluble means excretable, not unlimited. Anyone who takes a supplement is choosing not the nutrient, but an amount. This article cites the figures published by the authorities and explains which complaints are actually documented and which are merely passed around.
Chapter 2 explains why solubility says nothing about safety. Chapter 5 compares recommended intake and upper limits. Chapter 6 addresses the question of weight, while Chapter 8 explains who should ask before taking the first capsule.
What to expect in this article
1. One third take supplements, hardly anyone knows the limits
2. Water-soluble does not mean unlimited
3. Vitamin B6: the nerves set the limit
4. Niacin and folic acid: two more vitamins with a limit
5. Recommended intake, maximum amount, and upper limit at a glance
6. Does vitamin B12 make you gain weight? What the evidence shows
7. How to recognize that you are taking too much
8. Who a B-complex supplement is suitable for and who should ask first
9. What applies to Vitamin B-Complex Energize
10. Measure instead of guessing
11. What you can do now
Frequently asked questions
Sources
One third take supplements, hardly anyone knows the limits
A B-complex supplement rarely ends up in the shopping cart after lengthy research. Usually, it starts with a period of little sleep, a switch to a plant-based diet, or something someone says among friends and acquaintances. In 2024, the German Federal Institute for Risk Assessment (BfR) quantified how widespread this is: “About one third of adults regularly take dietary supplements, with vitamin and mineral supplements being particularly popular.” NEM is the German abbreviation for dietary supplements.
Anyone looking into whether this can be harmful will find two camps. One says B vitamins are water-soluble and therefore harmless. The other warns of nerve damage. Both contain an element of truth, and both are misleading as long as no number is attached. Such numbers exist for three of the eight B vitamins.
The numbers that matter
One third
of adults regularly take dietary supplements, according to the BfR, particularly vitamin and mineral supplements.
12 mg
Vitamin B6 per day as the EFSA upper limit for adults. Until 2023, the older value of 25 milligrams was shown here.
0.9 mg
Vitamin B6 per recommended daily serving of a supplement, proposed by the BfR for people aged 15 and over.
10 mg
Nicotinic acid per day as the upper limit for adults. The endpoint behind this is what is known as flushing.
Source: BfR, 2024 and 2021; EFSA, 2023
Water-soluble does not mean unlimited
The phrase “you just pee it out” describes what water-soluble means: the body stores very little of these vitamins, and excess amounts leave through the urine. For thiamine, riboflavin, pantothenic acid, and biotin, no upper limit is documented in the material reviewed here.
Excretion is still no guarantee of safety. It only says something about how long a substance remains in the body, not about what it does during that time. Effects have been described for vitamin B6 and niacin that do not depend on whether the substance is stored.
Key takeaway
Solubility describes how a substance leaves the body. It says nothing about the amount above which it has undesirable effects.
Two terms that are constantly confused
The authorities' assessments list two figures side by side that have nothing to do with each other. Anyone who confuses them may consider a completely harmless supplement concerning, or vice versa.
UL and maximum amount are two different figures
UL, the upper limit
UL stands for Tolerable Upper Intake Level. It refers to the total daily amount from all sources that, according to EFSA's assessment, remains free of known adverse effects even over the long term. The UL is neither a recommendation nor a target, but an upper limit.
Maximum amount, the recommendation for supplements
The maximum amount is the BfR's recommendation for how much a single food supplement should add per recommended daily serving. It is well below the UL because food counts too: What comes in through whole grains, meat, legumes, and fortified foods has already been consumed before the first capsule is counted.
What the individual B vitamins do in the body is explained in detail in our article on the effects, benefits, and safety of the vitamin B complex. Why the eight vitamins occur as a group in the first place and where they work together in metabolism is the subject of the article Understanding B vitamins as a whole. Here, we focus exclusively on the other direction: the upper limit.
Vitamin B6: the nerves set the limit
Vitamin B6 is the only B vitamin whose assessment has shifted noticeably in recent years. In 2000, the Scientific Committee on Food set an upper limit of 25 milligrams per day. In 2023, EFSA reassessed it and lowered it to 12 milligrams for adults. The panel identifies peripheral neuropathy as the critical effect - damage to nerves outside the brain and spinal cord, occurring primarily in the hands and feet.
It is important to clarify whom this affects at all. In 2023, EFSA noted that, based on the available consumption data, the EU population hardly exceeds the upper limit, with one exception: regular users of food supplements containing high doses of vitamin B6. It is not possible to reach these amounts through food alone. Anyone who reaches them does so through a supplement.
Documented source
“The German Federal Institute for Risk Assessment (BfR) recommends a maximum amount of 0.9 milligrams (mg) of vitamin B6 per recommended daily intake of a food supplement product for people aged 15 and over”
German Federal Institute for Risk Assessment
2024 update: Proposed maximum levels for vitamin B6 in foods, including food supplements, 2024
A factor of thirteen lies between 0.9 and 12 milligrams, and that is not a contradiction. The 12 milligrams are the upper limit for the total from all sources, while 0.9 milligrams is the proposed amount for addition to a single supplement. The BfR explicitly justifies the reduction with the new EFSA assessment and again cites the occurrence of peripheral neuropathies as the endpoint.
The converse is also true: tingling in the fingers is not proof of too much vitamin B6. It can have many causes, and insufficient intake is one of them. We have compiled the signs that point in this direction in Vitamin B6 deficiency and its symptoms. The assessment belongs in medical practice, not in a search engine.
Niacin and folic acid: two more vitamins with a limit
Niacin, the third B vitamin, occurs in two forms in supplements, and the difference determines tolerability. Nicotinic acid is the acidic form, nicotinamide the amide form. Both are simply listed as niacin on the label, but the BfR assesses them separately.
For nicotinic acid, the BfR specified a maximum level of 10 milligrams per day for adults in 2021. The toxicological endpoint behind this is the occurrence of flushing: a sudden widening of small blood vessels perceived as a wave of heat with reddening of the face and upper body. The BfR notes that this effect has only been observed in connection with isolated nicotinic acid or nicotinic acid added to foods, but not in connection with naturally occurring niacin levels in foods. For addition to food supplements, the institute proposes 4 milligrams per recommended daily intake.
For nicotinamide, the proposed amount of 160 milligrams per recommended daily intake is many times higher. The BfR attaches one condition to this: for preparations containing more than 16 milligrams of nicotinamide per recommended daily intake, it recommends a warning that pregnant women should refrain from taking such products. Anyone who is pregnant and has a B-complex supplement in the cupboard can find the form of niacin in the ingredients list.
For folic acid, the situation is simpler and the figure is lower. In 2024, the BfR derived a maximum amount of 200 micrograms of folic acid per daily dose of a food supplement, or an equivalent amount of other approved folate sources. For comparison: the D-A-CH recommendation (the joint reference values of the nutrition societies of Germany, Austria, and Switzerland) for adults is 300 micrograms of folate equivalents per day. Folate equivalent is a calculated quantity that puts natural folate from foods and synthetic folic acid on a common scale because the body utilizes the two differently efficiently.
One group is explicitly exempt from this. For women wishing to conceive, the BfR additionally recommends 400 micrograms of folic acid per day alongside a folate-rich diet. This recommendation stands alongside the general maximum amount; it does not conflict with it.
Chapter at a glance
Three of the eight B vitamins have a numerical limit in the assessments by EFSA and BfR: vitamin B6, niacin, and folic acid. For vitamin B6, the endpoint is nerve damage in the hands and feet; for nicotinic acid, it is flushing, which has only been described for the isolated acid form. For folic acid, the issue is not an adverse effect, but how much a preparation should add to food. For thiamine, riboflavin, pantothenic acid, biotin, and vitamin B12, these assessments contain no such figure.
Need, maximum amount, and upper limit at a glance
The following table places three figures side by side that are constantly mixed up in everyday life: what the body needs, how much a single preparation should add at most, and where the upper limit for everything combined lies. Where the reviewed material contains no figure, this is stated as well.
| Criterion | Recommended intake | Maximum amount per daily dose of a preparation | Overall maximum daily amount | Known adverse effect when taken in excess |
|---|---|---|---|---|
| Vitamin B6 | 1.6 mg for men, 1.4 mg for women (German Nutrition Society, DGE, 2019) | 0.9 mg from age 15 (BfR, 2024) | 12 mg for adults (EFSA, 2023) | Peripheral neuropathy, i.e. damage to the nerves in the hands and feet |
| Niacin as nicotinic acid | 15 mg equivalents for men, 12 mg equivalents for women aged 25 to 51 (DGE, 2015) | 4 mg (BfR, 2021) | 10 mg for adults (BfR, 2021) | Flushing, a wave of heat with reddening of the face and upper body |
| Niacin as nicotinamide | As above; the recommendation applies to niacin overall (DGE, 2015) | 160 mg; from 16 mg, with a warning for pregnant women (BfR, 2021) | not substantiated in the reviewed material | No flushing described; this effect is linked to the acid form |
| Folic acid | 300 µg dietary folate equivalents for adults, plus 400 µg when trying to conceive (BfR, 2024) | 200 µg or an equivalent amount from other approved folate sources (BfR, 2024) | not substantiated in the reviewed material | not substantiated in the reviewed material |
Vitamin B12, biotin, thiamine, riboflavin, and pantothenic acid are deliberately not included in this table. The reviewed assessments contain no upper limit of this kind for them, and an empty row would be more misleading than no row at all. The article on the effects and dosage of a B-complex with biotin shows how the amounts of individual vitamins are distributed in a finished supplement.
Does vitamin B12 make you gain weight? What the assessments show
Few questions appear as often in searches about B vitamins as the one about weight, and in both directions. One narrative says that a vitamin B12 deficiency makes you gain weight. The other says that the supplement makes you gain weight. Both continue to be passed on with the same certainty.
In the EFSA and BfR assessments reviewed for this article, weight gain is listed neither as an adverse effect of vitamin B12 nor as an adverse effect of a B-complex. We found no evidence for this, which is why this article contains no number, no percentage, and no sentence beginning with “Studies show”.
This is neither an all-clear nor a confirmation, but information about the available evidence. Someone who starts taking a supplement during a period of exhaustion and, during that same period, sleeps less, eats differently, and exercises less has made several changes at once. The supplement is the most visible of these, but not necessarily the most effective. How much vitamin B12 is needed at all and where it comes from is explained in How to properly meet your daily vitamin B12 requirement.
How to recognize that you are taking too much
Two signs are specifically named in the assessments, and only two. For vitamin B6, it is peripheral neuropathy, meaning nerve damage in the hands and feet that can manifest as tingling or numbness. For nicotinic acid, it is flushing, skin reddening accompanied by a feeling of heat.
Everything else circulating online belongs in a different category. Nausea after taking it is described, as is intensely yellow urine caused by riboflavin. For both, the reviewed material contains no dosage information and no regulatory assessment. The yellow color is a color effect, not a warning sign.
Water-soluble means excretable, not unlimited.
When to consult a doctor
Tingling or numbness in the hands and feet
This is the endpoint that the EFSA used in 2023 to justify the maximum level for vitamin B6. Take the preparation to your appointment so that the daily dose on the label can be discussed.
Persistent exhaustion without an apparent reason
Exhaustion can have many possible causes, and very few of them are resolved by a preparation. It should be medically assessed before considering supplementation.
Pregnancy or trying to conceive
Specific recommendations apply here, such as the BfR's advice for preparations containing more than 16 milligrams of nicotinamide and the folic acid recommendation when trying to conceive. This assessment belongs in a medical consultation.
Who a B complex is suitable for and who should ask first
In 2024, the BfR stated the starting point plainly: “As a rule of thumb, a balanced and varied diet provides a healthy body with sufficient essential nutrients.” A preparation is therefore the exception, for which there should be a reason, not the norm.
A B complex is suitable if …
you have changed your diet and largely eliminated animal-based foods.
you have read the daily dose on the label and can compare it with the figures in the table above.
you are not taking a second preparation with the same vitamins, because otherwise the amounts will add up.
you have a measurement rather than a suspicion.
Ask first if …
you are pregnant. For preparations containing more than 16 milligrams of nicotinamide per recommended daily intake, the BfR recommends an explicit warning advising pregnant women not to use them.
you have nerve symptoms, such as tingling or numbness in your hands and feet. These symptoms should be medically assessed before adding a preparation.
you take medication. Interactions should be clarified by a doctor's office or pharmacy, not by the package leaflet of a food supplement.
you combine several preparations. Maximum levels apply to each product; your body adds them together.
What applies to Vitamin B-Komplex Energize
A word belongs here about our own product. mybody®x (MYBODY Lab GmbH) itself offers a preparation with seven B vitamins, Vitamin B-Komplex Energize, and the rule from this article applies to it just as it does to any other product: The daily dose on the label is what matters, and it should be compared with the figures in the table above. We are not claiming here that the amounts are below the maximum levels. We do not have the amounts per daily dose for this product, so that is what we state rather than estimating.
The vitamins are formulated as micelle drops. Micelles are tiny spheres made of a fat and water shell that encloses an active ingredient. We do not say whether this improves absorption, because we have no evidence for it.
What a manufacturer may say about B vitamins is regulated at the European level and narrowly defined. Permitted claims include “contributes to the reduction of tiredness and fatigue,” “contributes to the normal function of the nervous system,” or “contributes to normal psychological function.” Each of these claims is subject to a condition of use: The food must be at least a “source of” the respective vitamin, meaning it must contain 15% of the reference intake per 100 grams, per 100 milliliters, or per serving (Regulation (EU) No 432/2012, Official Journal L 136 of 25.05.2012). This is a statement about a food and its composition, not a statement about what happens to you.
Food supplement
Vitamin B Complex | Energize
Seven B vitamins as micellar drops, developed and manufactured in Switzerland. The supplement does not replace a measurement and does not tell you whether you are deficient in anything. The daily dose is stated on the label and should be compared with the maximum amounts in the table above.
no finding is generated
in Switzerland
Measure instead of guessing
The uncomfortable truth behind the entire question of side effects is this: People who buy a supplement often do not know whether they are deficient in anything at all. A supplement is purchased because a condition seems to require an explanation, not because a measurement suggests it. Afterwards, people discuss threshold values without knowing what the starting point was.
A measurement reverses this sequence. It provides a data point that makes it possible to meaningfully consider whether you need more, and it gives you something to present during a consultation with your doctor. What such a test covers and what it does not is explained in our article on the vitamin B test. A result is not a finding or a diagnosis. It is a starting point.
What you can do now
Take your supplement out of the cupboard and read the back. You are looking for three details: the amount of vitamin B6 per daily dose, the form of niacin, namely nicotinic acid or nicotinamide, and the amount of folic acid. Compare these three lines with the table in Chapter 5. In two minutes, you will have clarified what might otherwise remain a vague discomfort for weeks.
If you take several supplements, add up the vitamins. Maximum amounts are recommendations for a single product; your body does not recognize this distinction. And if tingling or numbness occurs, that is not a reason for further research, but for making an appointment.
At first, the question was whether B vitamins are harmless because they are water-soluble. The more honest question is how much you are taking and how you know you need it. Your label answers the first question. A measurement answers the second.
Frequently asked questions
Can you overdose on a vitamin B complex?
There is a numerical upper limit for three of the vitamins included. For vitamin B6, EFSA gives an upper limit of 12 milligrams per day for adults in 2023, while for nicotinic acid the BfR stated an upper limit of 10 milligrams per day in 2021. For thiamine, riboflavin, pantothenic acid, biotin, and vitamin B12, these assessments contain no such figure. Only the daily dose on the label shows whether your supplement is approaching the limits.
Why does a B complex turn urine yellow?
This effect is described for riboflavin, or vitamin B2. The substance itself is yellow, and anything the body does not use leaves it through the urine. In the EFSA and BfR assessments reviewed for this article, the discoloration is not listed as an adverse effect and is not linked to any dosage. It shows that something is being excreted, not that a limit has been exceeded.
Can I take a B complex during pregnancy?
This decision belongs in a medical or gynecological practice, not in a guide. What can be stated here based on evidence is that in 2021 the BfR recommended that supplements containing more than 16 milligrams of nicotinamide per recommended daily intake should carry a notice advising pregnant women to avoid taking such products. For women wishing to conceive, in addition to a folate-rich diet, the institute also recommends 400 micrograms of folic acid per day as of 2024. Take the label with you to your appointment.
What is the difference between nicotinic acid and nicotinamide?
Both are forms of niacin, or vitamin B3, and they often appear under the same name on the label. The difference is significant for tolerability. In 2021, the BfR proposed 4 milligrams of nicotinic acid per recommended daily intake for use in supplements, compared with 160 milligrams for nicotinamide. According to this assessment, flushing, meaning a wave of heat with redness, is linked to the isolated acid form and was not observed with natural niacin levels in foods.
What happens if I take several supplements at the same time?
The BfR's maximum levels always refer to the recommended daily intake of a single product. If you take a multivitamin, a B complex, and an individual vitamin at the same time, the amounts add up in your body without any one label showing this. Add up the amounts before comparing them with the figures in Chapter 5, and include fortified foods such as breakfast cereals.
Next step
The value first, then the decision
A search query and the back of a package cannot show whether you are deficient. A measurement can. If you already take a supplement, the label shows the amounts relevant to this article.
Take the vitamin B test View productRead more
You might also be interested in
The other side of the same question: what amount makes sense and what it is based on.
The B vitamin with the biggest promises and the thinnest evidence base.
Sources
- EFSA NDA Panel: Scientific opinion on the tolerable upper intake level for vitamin B6, EFSA Journal 2023;21(5):e08006 (as of 2023) - pmc.ncbi.nlm.nih.gov
- German Federal Institute for Risk Assessment: 2024 update, proposed maximum levels for vitamin B6 in foods, including food supplements (as of 2024) - bfr.bund.de
- German Federal Institute for Risk Assessment: Proposed maximum levels for niacin in foods, including food supplements, Annex to Opinion 009/2021 (as of 2021) - bfr.bund.de
- German Federal Institute for Risk Assessment: 2024 update, proposed maximum levels for folic acid in foods, including food supplements, Opinion 009/2024 (as of 2024) - bfr.bund.de
- German Federal Institute for Risk Assessment: Updated proposed maximum levels for vitamins and minerals in food supplements and fortified foods, Opinion 006/2024 (as of 2024) - bfr.bund.de
- European Commission: Regulation (EU) No 432/2012, Annex, OJ L 136 of 25.05.2012 (as of 2012) - Official Journal reference, no link
The maximum value of 12 milligrams of vitamin B6 and the information about high-dose users come from [1]. The maximum amount of 0.9 milligrams and the explanation concerning peripheral neuropathies are provided in [2]. All information on niacin, namely nicotinic acid, nicotinamide, flushing, and the advice for pregnant women, comes from [3]. The folic acid values and the D-A-CH recommendation are provided in [4], while the information on the prevalence of food supplement use and the rule of thumb for nutrition come from [5]. The permitted claims and their conditions of use follow [6]. The reference values for vitamin B6 (DGE, 2019) and niacin (DGE, 2015) in the table come from the reference values of the German Nutrition Society. Product information and the price on the mybody®x product page were checked on 09.09.2026.
mybody®x editorial & specialist team
Food supplement B vitamins Maximum amounts
This article was compiled by the mybody®x specialist team and is supported exclusively by publications from EFSA, BfR, and DGE. The contributors are listed on the authors page.
Published on 09.09.2026 · Last updated on 09.09.2026
The content is provided for general information and does not replace medical advice, diagnosis, or treatment. Reference ranges depend on the laboratory, method, and age - the information on your report is always authoritative.
Our products are not intended to diagnose, treat, cure, or prevent diseases.
Share now:
Lactose tablets: how they work and when they may be appropriate
Vitamin D supplements: drops, capsules, or tablets, D2 or D3