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Dimenhydrinate for >65 y/o

Question# 746

Do PCP need to consult a BHP for patients >65 yo for gravol? or is it appropriate it give 25mg.


We’ve heard your frustration as you try to follow the Standards in the face of sometimes conflicting information. Dr. Austin will be speaking to this in Fall CME 2023.

The addition of ondansetron to the Patient Care Standards to treat nausea and vomiting was meant as a safer alternative to dimenhydrinate - Gravol - in older patients.

But the rollout of ondansetron has been complicated by supply shortages and confusion about how best to treat patients 65 and older with nausea and vomiting.

Evidence shows that older adults are at risk for increased anticholinergic effects such as somnolence, confusion, delirium, and urinary retention with medications like dimenhydrinate. This is because chronic disease processes can affect drug metabolism.

Another complicating factor is that older people are sometimes on complex pharmaceutical regimes. Many medications interact with dimenhydrinate and may worsen its adverse effects. For these reasons, ondansetron is going to be the safest antiemetic for your older patients in most cases.

In motion sickness, remember that ondansetron has little effect. You’ll want to look to dimenhydrinate for nausea or vomiting caused by inner ear imbalances during motion and weigh the risk benefit of the potential adverse effects.

For a patient who’s 65 or older, you need to patch if you’re considering dimenhydrinate. The Patient Care Standards do not provide standing orders for dimenhydrinate in patients 65 or older unless ondansetron is not available. So, by calling a base hospital physician you can discuss the appropriateness and risks of dimenhydrinate for these patients.

The therapeutic dose of dimenhydrinate is 25 to 50 milligrams. For the older patient, be sure to consider an initial lower dose. 25 mg of dimenhydrinate is often a safer option that still offers the therapeutic benefits with less potential for adverse effects. You can always give more, but you can’t take away what you’ve already given.

To summarize, regardless if you are an ACP or a PCP, you must patch to a BHP to administer dimenhydrinate to a patient greater than 65 years of age unless Ondansetron is unavailable. It would be wise to ask to administer a dose of 25 milligrams for the reasons stated above.


Dr. Austin's Fall CME 2023 Video:

Medical Directive Category



07 November 2023

ALSPCS Version




Please reference the MOST RECENT ALS PCS for updates and changes to these directives.