Diphenhydramine Hydrochloride vs Citrate: What's the difference?
The difference between diphenhydramine hydrochloride and diphenhydramine citrate is that the salt used to bind the diphenhydramine, is different. For diphenhydramine hydrochloride the salt is hydrochloride and for diphenhydramine citrate the salt is citrate. This salt can change how quickly and effectively the diphenhydramine dissolves and is absorbed but once it is in the body it has no effect. Essentially 25 mg of diphenhydramine hydrochloride is equivalent to 38 mg of diphenhydramine citrate.
Diphenhydramine is actually available in four different salts:
- Diphenhydramine citrate
- Diphenhydramine hydrochloride
- Diphenhydramine methylbromide
- Diphenhydramine salicylate.
Only diphenhydramine citrate and diphenhydramine hydrochloride are used commercially.
The different salts have different molecular weights (diphenhydramine hydrochloride: 291.8 g/mol, diphenhydramine citrate: 447.5 g/mol) and rates of dissolution and absorption characteristics. Therefore the dosage differs depending on the salt used.
The following oral dosages for adults are given by the manufacturers. Dosages for children vary depending on age or body weight: please consult with a pediatrician.
Allergic rhinitis
- Diphenhydramine citrate: 38mg to 76mg up to every 4-6 six hours as needed. Maximum 456 mg/day
- Diphenhydramine hydrochloride: 25mg to 50 mg up to every 4-6 six hours as needed. Maximum 300 mg/day.
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Cold symptoms, itch (pruritus), or urticaria
- Diphenhydramine citrate: 38mg to 76mg up to every 4-6 six hours as needed. Maximum 456 mg/day
- Diphenhydramine hydrochloride: 25mg to 50 mg up to every 4-6 six hours as needed. Maximum 300 mg/day
Insomnia
- Diphenhydramine citrate: 76mg once at bedtime. Maximum dose 76mg
- Diphenhydramine hydrochloride: 50mg once at bedtime. Maximum dose 50mg
Motion sickness
- Diphenhydramine hydrochloride: 25mg to 50mg up to 3 to 4 times a day as needed
Note that these dosages are for adults who are otherwise healthy and are on no interacting medicines. The dosage of diphenhydramine may need reducing in those with certain medical conditions or taking certain medicines. Diphenhydramine may not be suitable for some
What brands contain diphenhydramine hydrochloride and diphenhydramine citrate?
Common brands containing diphenhydramine and the salt they contain include:
- Advil PM (diphenhydramine citrate)
- Aleve PM (diphenhydramine hydrochloride)
- Bayer PM (diphenhydramine citrate)
- Benadryl (diphenhydramine hydrochloride)
- Dimetapp (diphenhydramine hydrochloride)
- Ivarest (diphenhydramine hydrochloride)
- Sominex (diphenhydramine hydrochloride)
- Tylenol PM (diphenhydramine hydrochloride)
- Unisom (diphenhydramine hydrochloride).
Read next
Does diphenhydramine raise blood pressure?
Increased blood pressure is not a typical side effect of diphenhydramine, a first-generation antihistamine that lowers the effects of histamines in your body. However, in rare cases, the drug may cause hypotension, or decreased blood pressure. This side effect is most likely to occur in people who are over the age of 60. Continue reading
Does Benadryl help with or cause anxiety?
One of the most common side effects with Benadryl is drowsiness, but in some people it can have the opposite effect, known as paradoxical excitation. Instead of feeling sleepy,
you may experience excitation, agitation or insomnia (trouble sleeping), which might make your anxiety symptoms feel worse. This may be more common in young children. Continue reading
Can diphenhydramine be used as a sleep aid?
Diphenhydramine can be used as a short-term sleep aid to help ease occasional sleep problems, such as when you have a cold or cough and it is preventing you from falling asleep. Older adults, children under age 16 and pregnant women should avoid taking diphenhydramine, as the risks to these groups may outweigh the benefits. Continue reading
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Drug information
- Diphenhydramine Information for Consumers
- Diphenhydramine prescribing info & package insert (for Health Professionals)
- Side Effects of Diphenhydramine (detailed)
- Diphenhydramine user reviews (541)
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