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Dimenhydrinate (Dimenhydrinate) - Warnings and Precautions



Caution should be used when dimenhydrinate is given in conjunction with certain antibiotics that may cause ototoxicity, since dimenhydrinate is capable of masking ototoxic symptoms, and an irreversible state may be reached.

This drug may impair the mental and/or physical abilities required for the performance of potentially hazardous tasks, such as driving a vehicle or operating machinery.  The concomitant use of alcohol or other central nervous system depressants may have an additive effect. Therefore, patients should be warned accordingly.

Dimenhydrinate should be used with caution in patients having conditions which might be aggravated by anticholinergic therapy (i.e., prostatic hypertrophy, stenosing peptic ulcer, pyloroduodenal obstruction, bladder neck obstruction, narrow-angle glaucoma, bronchial asthma, or cardiac arrhythmias).

The preparation should not be injected intra-arterially.

Pediatric Patients

For infants and children especially, antihistamines in overdosage may cause hallucinations, convulsions, or death.

As in adults, antihistamines may diminish mental alertness in pediatric patients.  In the young child, particularly, they may produce excitation (see CONTRAINDICATIONS ).



Drowsiness may be experienced by some patients, especially with high dosage.  This effect frequently is not undesirable in conditions for which the drug is used.

Information for Patients

Because of the potential for drowsiness, patients taking dimenhydrinate should be cautioned against operating automobiles or dangerous machinery (see WARNINGS ).

Carcinogenesis, Mutagenesis, Impairment of Fertility

Mutagenicity screening tests performed with dimenhydrinate, diphenhydramine, and 8-chlorotheophylline produced positive results in the bacterial systems and negative results in the mammalian systems.  There are no human data that indicate dimenhydrinate is a carcinogen or mutagen or that it impairs fertility.


Pregnancy Category B.

Reproduction studies have been performed in rats at doses up to 20 times the human dose, and in rabbits at doses up to 25 times the human dose (on a mg/kg basis), and have revealed no evidence of impaired fertility or harm to the fetus due to dimenhydrinate. There are no adequate and well-controlled studies in pregnant women.  However, clinical studies in pregnant women have not indicated that dimenhydrinate increases the risk of abnormalities when administered in any trimester of pregnancy.  It would appear that the possibility of fetal harm is remote when the drug is used during pregnancy.  Nevertheless, because the studies in humans cannot rule out the possibility of harm, dimenhydrinate should be used during pregnancy only if clearly needed.

Labor and Delivery

The safety of dimenhydrinate given during labor and delivery has not been established. Reports have indicated dimenhydrinate may have an oxytocic effect.  Caution is advised when this effect is unwanted or in situations where it may prove detrimental.

Nursing Mothers

Small amounts of dimenhydrinate are excreted in breast milk.  Because of the potential for adverse reactions in nursing infants from dimenhydrinate, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother.

Page last updated: 2011-08-23

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