B-Complex Vitamins: uses, dosing, side effects & brands
B-Complex Vitamins is a medicine sold in the U.S. under one brand. Below: what the FDA label says, every product that contains it, what the pills look like, and its recall record.
Key facts
- Available as
- Injectable
- Sold as
- Vitamin B Complex
- Generic available?
- Not in our catalog
How b-complex vitamins is dosed
From the FDA label for Vitamin B Complex. Other b-complex vitamins products — different forms, different strengths — are dosed differently. Follow the label for the one you were prescribed.
Usually 0.25 to 2 mL by intramuscular or slow intravenous injection. High concentrations given intravenously may be diluted using parenteral infusion solutions. (See PRECAUTIONS .) Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration, whenever the solution and container permit (see HOW SUPPLIED ).
B-Complex Vitamins side effects
Mild transient diarrhea, polycythemia vera, peripheral vascular thrombosis, itching transitory exanthema, feeling of swelling of entire body, anaphylactic shock and death. Sensitivity to the ingredients listed may occur (see WARNINGS ). Use should be discontinued upon observance of any untoward reaction. Pain upon intramuscular injection may be noted.
Who shouldn’t take b-complex vitamins
Sensitivity to the ingredients listed.
Every b-complex vitamins product we track (1)
Same active ingredient — different manufacturer, form, price and FDA recall record. That last one is what our independent score measures.
Only one: Vitamin B Complex.
What people report to the FDA about b-complex vitamins
The FDA Adverse Event Reporting System (FAERS) collects reports from patients and clinicians. It holds 136 reports naming b-complex vitamins, and the FDA flagged 68% of those reports as serious. The effects reported most often — leaving out reports about overdose, misuse or the condition being treated, which dominate the raw list for common medicines:
- dizziness14 reports
- headache12 reports
- nausea12 reports
- dyspnoea10 reports
- abdominal pain7 reports
- fatigue7 reports
- insomnia7 reports
- pain in extremity7 reports
Read these as a signal, not a rate. A report does not mean b-complex vitamins caused the effect — anyone can file one, and many describe people taking several medicines for several conditions. Crucially there is no denominator: FAERS does not record how many people took the drug, so these counts cannot be turned into “X% of patients” — a bigger number often just means a more widely used or more talked-about drug. Duplicates exist, and publicity drives reporting. For what is actually established, read the FDA label section above.
Source: openFDA drug/event (FAERS), retrieved July 25, 2026.
Related calculators
Frequently asked questions
What is b-complex vitamins?
Vitamin B-Complex 100 Injection is a sterile solution for intramuscular or slow intravenous injection comprised of vitamins which may be categorized as belonging to the vitamin B complex group. Each mL contains: Thiamine Hydrochloride 100 mg, Riboflavin 5’ Phosphate Sodium 2 mg, Pyridoxine Hydrochloride 2 mg, Dexpanthenol 2 mg, Niacinamide 100 mg, with Benzyl Alcohol 2% as preservative, in Water for Injection. Sodium Hydroxide and/or Hydrochloric Acid may have been used to adjust pH.
Can you take b-complex vitamins with other medicines?
It depends on the medicine. We check it against the FDA labels rather than guessing: our interaction checker searches each drug's own label for the other and quotes what it says, naming the section it came from. Run b-complex vitamins against whatever else you take — and remember that a label not naming a drug is not the same as that combination being safe.
What forms does b-complex vitamins come in?
Across the brands we track, b-complex vitamins is currently marketed as injectable, per the FDA's National Drug Code Directory. Each form is dosed differently — follow the label for the exact product you were prescribed.
Is there a generic b-complex vitamins?
We do not currently list a generic-labelled b-complex vitamins product. That does not always mean none exists — it means none appears under a generic name in the FDA data we track. Ask your pharmacist.
Cite this page
- APA
- pharmaranks. (2026, July 24). B-Complex Vitamins: uses, dosing, side effects & brands. https://pharmaranks.com/drugs/b-complex-vitamins
- MLA
- “B-Complex Vitamins: uses, dosing, side effects & brands.” pharmaranks, 24 July 2026, https://pharmaranks.com/drugs/b-complex-vitamins.
We summarise public FDA and NIH sources — for a clinical claim, cite the primary source we link to as well.
Sources: FDA openFDA drug label, National Drug Code Directory, and Enforcement (recall) database. This page reproduces public FDA data and is not medical advice. Dosing is set by your prescriber.
Read the full FDA label for b-complex vitamins on DailyMed (NIH) ↗.