What Is Dimenhydrinate?

Dimenhydrinate is an antihistamine that is principally employed to treat or prevent motion sickness and carsickness symptoms or to address symptoms of nausea from conditions like Meniere’s disease. This over-the-counter medication is sometimes available in prescription only strengths, too. Like all medications, this antihistamine has a few noted drug interactions and side effects. Some people may have medical conditions contraindicating its use.

It’s common for antihistamines to treat symptoms like dizziness, vertigo, nausea, and vomiting. They act on areas of the brain that can cause stimulation of vomiting and may help to provide a calming effect that decreases symptoms. In particular, dimenhydrinate is well known for its antiemetic properties, and it is frequently used for mild to moderate motion sickness. Sometimes the drug is indicated to prevent nausea in chemotherapy, but doctors don’t always feel it is effective enough. Other antiemetics with stronger action may be more appropriate in some circumstances.

Most often, people can find over-the-counter formulations of dimenhydrinate. Typically, pills and elixirs are the most common forms. The drug may be sold under different brand names and there may be adult and child formulas. Stronger versions come in injectable and intravenous forms, and some countries may also have prescription strength tablets.

Dimenhydrinate has a short list of side effects. The most noted is drowsiness, which is common with antihistamines. Some people feel an increase in dizziness when they use this drug. Others may continue to have vomiting or upset stomach. Additional side effects include blurred vision, dry mouth, and reduced urination. In rare instances, people experience hallucinations with this drug, but usually only if they well exceed the recommended amounts.

There are drugs and other substances that can interact with dimenhydrinate. Alcohol can definitely cause increased drowsiness or dizziness, and it should be avoided. Many opioid pain relievers, sleep medications, tranquilizers, and psychoactive drugs can cause greater drowsiness. These drugs don’t necessarily need to be avoided, but a doctor’s opinion on using this antihistamine with them should be sought.

Similarly, any ongoing health problem warrants discussion with a doctor prior to using dimenhydrinate. Some patients are advised to avoid this medication. It’s usually not recommended for those with prostate enlargement, bladder problems, or conditions that impact urinary frequency.

Furthermore, patients with heart disease and especially with any type of heart rhythm disorders shouldn’t use this drug. Pregnant women should try this medication only under a physician's guidance. It may also not be appropriate for nursing women because dimenhydrinate passes into breast milk.