No - a scoping review of 104 papers found thiamine's support is entirely anecdotal or from uncontrolled trials; controlled experiments on insect landing and feeding found no repellency, and the authors conclude thiamine cannot repel arthropods at any dose.
The stakes: trusting a debunked repellent in dengue or malaria country substitutes a placebo for real defense. The same literature's gold standard: topical DEET - safest and most effective across decades of evidence, safe over 2 months of age including pregnancy - with picaridin as the odorless equal. Pymander's escalation routing is built and tested specifically for this class of decision; see the safety architecture working paper .
What to do
Common questions
Does vitamin B repel mosquitoes?
No - this myth has been tested for 80 years and the verdict is now as settled as science gets. Vitamin B1 (thiamine) has been touted as an oral mosquito repellent since 1943, but a scoping review in the Bulletin of Entomological Research traced 104 case reports, studies, and reviews and found the support is entirely anecdotal or from uncontrolled trials that counted itch symptoms instead of actual bites; controlled experiments measuring insect landing and feeding found no evidence of repellency - the authors' conclusion is flat: thiamine cannot repel arthropods at any dosage or route. The stakes are not academic: the review warns that trusting a debunked repellent in dengue or malaria country substitutes a placebo for a real defense. What the same literature calls the gold standard instead: topical DEET - the safest and most effective repellent across decades of studies, safe for anyone over 2 months old including pregnancy - with picaridin as the equally effective odorless alternative. Enjoy B vitamins for what they do inside the body; for the skin that mosquitoes see, only a registered topical repellent changes the math.