From the Guidelines
Antihistamines are effective in treating nausea by blocking histamine receptors in the brain, particularly H1 receptors in the vomiting center and vestibular system, as supported by the most recent evidence from 1 and 1. The most commonly used antihistamines for nausea include dimenhydrinate (Dramamine), meclizine (Antivert, Bonine), and promethazine (Phenergan). For motion sickness, meclizine is typically taken at 25-50 mg doses 1 hour before travel, while dimenhydrinate is usually taken as 50-100 mg every 4-6 hours. Promethazine can be prescribed at 12.5-25 mg every 4-6 hours for more severe nausea. These medications work by preventing histamine from triggering the vomiting reflex and by reducing sensitivity in the inner ear's balance center, which helps with motion-related nausea. They also have anticholinergic properties that further suppress the vomiting center. Side effects may include drowsiness, dry mouth, and blurred vision, so users should avoid driving or operating machinery until they know how the medication affects them. First-generation antihistamines (like those mentioned) are more effective for nausea than newer, non-sedating antihistamines because they cross the blood-brain barrier more readily, as noted in 1.
Some key points to consider when using antihistamines for nausea include:
- The potential for sedation and performance impairment, particularly with first-generation antihistamines, as discussed in 1
- The importance of avoiding driving or operating machinery until the user knows how the medication affects them
- The potential for anticholinergic effects, such as dry mouth and constipation, particularly with first-generation antihistamines
- The need to use caution when prescribing antihistamines to older adults or individuals with certain comorbid conditions, as noted in 1
Overall, antihistamines can be a effective treatment option for nausea, particularly when used in conjunction with other medications and therapies, as supported by the evidence from 1, 1, and 1.
From the Research
Antihistamines and Nausea Treatment
- Antihistamines have been used to manage motion sickness, which often includes symptoms of nausea and vomiting 2.
- The study found that antihistamines are probably more effective than placebo at preventing motion sickness symptoms under natural conditions, with a risk ratio of 1.81 2.
- However, there is no clear evidence on the resolution of existing motion sickness symptoms, including nausea, as no studies reported results on this outcome 2.
- Antihistamines may result in little or no difference in gastric tachyarrhythmia, a physiological measure related to nausea, under experimental conditions 2.
Comparison with Other Treatments
- The evidence is very uncertain about the effect of antihistamines on preventing motion sickness under natural conditions when compared to scopolamine 2.
- Antihistamines may result in little or no difference in the prevention of motion sickness under experimental conditions when compared to antiemetics 2.
- The evidence is very uncertain about the effects of antihistamines on the prevention of motion sickness under experimental conditions when compared to acupuncture 2.