DIMENHYDRINATE

What is dimenhydrinate?

Dimenhydrinate is a first-generation antihistamine commonly used for motion sickness, nausea, vomiting, and vertigo (a sensation that you or your surroundings are spinning). It is similar to meclizine (another over-the-counter antihistamine used for motion sickness and vertigo), but dimenhydrinate is considered to be more sedating. Compared to meclizine, which takes an hour to take effect but lasts 24 hours, dimenhydrinate has a faster onset of action of about 15 to 30 minutes but takes about an hour. Dimenhydrinate can be taken as 50-100 mg every four to six hours as needed for a maximum of 400 mg daily.

How can dimenhydrinate help alleviate certain long COVID symptoms? 

Some patients have reported neurological symptoms of long COVID, such as vertigo and persistent dizziness. While rare, there have been reports of new-onset vertigo associated with a COVID infection.¹ It is known that the SARS-CoV-2 virus can infiltrate the central nervous system and directly invade the brain. The mechanism of its association with vertigo is still unclear. Still, it is thought to be due to the effect of the virus on neural networks impacting our hearing and balance or cytokine storm that occurs when immune cells become hyperactivated and trigger an excess release of inflammatory mediators.² Dizziness can also be due to multiple factors such as dehydration, headache, and lightheadedness due to stress from the infection.

Dimenhydrinate can block certain receptors in the chemoreceptor trigger zone in our brain, which is responsible for causing feelings of nausea and dizziness. This allows for relief of vertigo and dizziness from neurological long COVID symptoms.

What evidence supports dimenhydrinate’s use for long COVID?

More studies are currently needed to explore the use of dimenhydrinate specifically for new-onset vertigo or dizziness after a COVID infection. In addition, patient case reports and anecdotal reports are mixed, with some reporting beneficial effects and others stating partial or no improvement in their vertigo. A case report of a patient treated with dimenhydrinate and beta-histamine (a prescription antiemetic not available in the US) led to partial improvement in vertigo.³ For patients with gastrointestinal effects from COVID, such as nausea and diarrhea, dimenhydrinate can help with oral intake and rehydration.⁴

Overall, dimenhydrinate is a reasonable option to consider for post-COVID vertigo or dizziness and can be trialed with other prescription medications. However, it should not be used chronically if these symptoms persist.

What should you be aware of when taking dimenhydrinate?

Due to its sedating effects, dimenhydrinate should not be taken while driving or operating heavy machinery. Other side effects of the medication include a fast heartbeat or palpitations, dizziness, headache, restlessness, blurred vision, difficulty urinating, or constipation. Some of these side effects can be worsened with other medications and older age. If used more frequently, it should be used with caution in patients with cardiovascular disease, angle-closure glaucoma, and urinary obstruction.

References:

1)      Devaragudi S, Gupta M. Vertigo in the Setting of COVID-19 Infection: A Case Report. Cureus. 2023 Feb 6;15(2):e34708. doi: 10.7759/cureus.34708

2)      Korres G, Kitsos DK, Kaski D, Tsogka A, Giannopoulos S, Giannopapas V, Sideris G, Tyrellis G, Voumvourakis K. The Prevalence of Dizziness and Vertigo in COVID-19 Patients: A Systematic Review. Brain Sci. 2022 Jul 20;12(7):948. doi: 10.3390/brainsci12070948

3)      Menezes IL, Velloso LAF. Early vertigo in a patient with oligosymptomatic and prolonged COVID-19: a case report. Rev Med Minas Gerais. 2022 May 27;32:e-32404. doi: 10.5935/2238-3182.2022e32404.

4)      El Ouali S, Achkar JP, Lashner B, Regueiro M. Gastrointestinal manifestations of COVID-19. Cleve Clin J Med. 2021 Feb 17. doi: 10.3949/ccjm.87a.ccc049