From the Guidelines
Meclizine, as a first-generation antihistamine, is associated with significant side effects, including sedation, performance impairment, and anticholinergic effects, which can be potentially dangerous, especially in older adults and when combined with other CNS-active substances 1. Meclizine can cause several side effects, including:
- Drowsiness and fatigue
- Dry mouth and eyes
- Constipation
- Inhibition of micturition
- Increased risk for provocation of narrow angle glaucoma
- Blurred vision
- Headaches
- Confusion and difficulty urinating in more severe cases
- Allergic reactions such as rash or itching These side effects are more pronounced in older adults, who are more sensitive to the psychomotor impairment promoted by first-generation antihistamines, and are at increased risk for complications such as fractures and subdural hematomas caused by falls 1. The use of meclizine should be approached with caution, especially in older adults, due to the potential for adverse anticholinergic effects and the increased risk of falls and other complications 1. It is essential for patients to be aware of the potential side effects of meclizine and to avoid driving or operating heavy machinery until they know how the medication affects them, as the sedating effects can be significant 1. Additionally, patients should avoid consuming alcohol while taking meclizine, as it can intensify drowsiness and other side effects. Overall, the potential benefits of meclizine must be carefully weighed against the risks of side effects, particularly in vulnerable populations such as older adults 1.
From the FDA Drug Label
The following adverse reactions associated with the use of meclizine hydrochloride were identified in clinical studies or postmarketing reports. Because some of these reactions were reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure. Anaphylactic reaction, drowsiness, dry mouth, headache, fatigue, and vomiting. On rare occasions blurred vision has been reported. Advise patients that meclizine hydrochloride tablets may cause anaphylactic reaction, drowsiness, dry mouth, headache, fatigue, vomiting and, on rare occasions, blurred vision
The side effects of meclizine include:
- Anaphylactic reaction
- Drowsiness
- Dry mouth
- Headache
- Fatigue
- Vomiting
- Blurred vision (on rare occasions) 2 2
From the Research
Meclizine Side Effects
- The side effects of meclizine, an antihistamine, are not extensively discussed in the provided studies, but some information can be gathered from the texts:
- Meclizine is compared to other antihistamines and scopolamine in terms of efficacy and side effects in the treatment of motion sickness 3, 4.
- A study on the effects of meclizine on motion sickness revisited found that meclizine led to a relative increase in torsional velocity compared to placebo during vestibular stimulation, but its use may be counterproductive in high-acceleration environments 5.
- Meclizine metabolism and pharmacokinetics were studied, and it was found that CYP2D6 is the dominant enzyme for metabolism of meclizine, and its genetic polymorphism could contribute to the large interindividual variability 6.
- Common side effects of antihistamines, which may also apply to meclizine, include:
- It is essential to note that the provided studies do not directly focus on the side effects of meclizine, and more research would be necessary to fully understand its side effect profile.