Do children’s Benadryl and gravol have the same effective ingredient?
Gravol, or Dimenhydrinate, is actually diphenhydramine chemically joined to another compound. Children's Benadryl is diphenhydramine. The body breaks down dimenhydrinate into diphenhydramine as the active ingredient in the body.
Both have the same active ingredient and are first generation antihistamines, but Benadryl is marketed for allergies and Gravol for nausea and motion sickness.
Good
Based on Health Canada's official drug product database and labelling standards, which are regulatory-grade sources rather than clinical trials, but are authoritative for ingredient identity questions.
What the evidence says
Children's Benadryl and Gravol are more closely related than you might think. Benadryl's active ingredient is diphenhydramine. Gravol's active ingredient is dimenhydrinate, which is actually made of diphenhydramine chemically combined with another substance called 8-chlorotheophylline.
Health Canada's official drug database confirms this. Children's Benadryl Allergy Liquid is listed with diphenhydramine as its single active ingredient, while Gravol products are listed separately under dimenhydrinate, each with its own unique ingredient code.
Because dimenhydrinate breaks down into diphenhydramine in the body, both medicines have the same active antihistamine ingredient and can make a child drowsy. But they are marketed for different jobs. Benadryl is meant for allergy symptoms like itching, sneezing and hives. Gravol is meant for nausea and motion sickness, especially the queasy feeling from car or boat travel.
Because the two drugs overlap in how they work, giving both at the same time is not a good idea without checking with a doctor or pharmacist first. Doing so could double up on the sedating and other side effects, such as drowsiness or, in rare cases, restlessness.
Health Canada has also flagged safety concerns about diphenhydramine-containing products in young children, including cases of accidental overdose and side effects like agitation or fast heart rate, particularly when caregivers were unaware of the risks. This is a good reason to always check doses carefully and talk to a pharmacist before combining any two antihistamine-type products.
Sources
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Guideline
Dimenhydrinate Labelling Standard
Health Canada
Sets Canadian rules for dimenhydrinate (Gravol) as a distinct medicinal ingredient.
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Guideline
Health Product InfoWatch: diphenhydramine safety review
Health Canada
Health Canada review of serious adverse events with diphenhydramine in children.
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Guideline
Diphenhydramine (oral) medication information
HealthLink BC
Canadian consumer guide identifying diphenhydramine as Benadryl's ingredient.
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Guideline
Dimenhydrinate (oral) medication information
HealthLink BC
Canadian consumer guide identifying dimenhydrinate as Gravol's ingredient.
✓Reviewed by CH, MD, FRCPC
Reviewed by a specialist physician certified by the Royal College of Physicians and Surgeons of Canada, who has read this answer against the sources listed above and confirmed it reflects them. That is not medical advice about your child. How we review
Answer checked September 2, 2026