Who Should Not Use Meclizine?

October 14, 2025 •

4 min read

Meclizine is an antihistamine commonly used for motion sickness and vertigo [1.2.5]. However, due to its anticholinergic properties and potential for drowsiness, there are specific populations who should not use meclizine or should use it only with caution [1.4.3, 1.7.2].

Quick Summary

Certain individuals should avoid meclizine, including those with allergies to it, specific medical conditions like glaucoma or an enlarged prostate, and children under 12. Caution is advised for older adults and those taking other CNS depressants.

Key Points

Allergic Reactions: Individuals with a known hypersensitivity to meclizine should not use it [1.3.1].
Certain Medical Conditions: People with glaucoma, asthma, or an enlarged prostate should avoid meclizine as it can worsen these conditions [1.7.1, 1.7.3].
Older Adults: Use in adults 65 and older is generally not recommended due to increased risks of falls, confusion, and cognitive impairment [1.4.3, 1.4.5].
Children: Meclizine is not recommended for children under 12 years old as its safety and efficacy have not been established [1.9.3, 1.9.4].
CNS Depressants: Do not combine meclizine with alcohol, opioids, sedatives, or other CNS depressants due to the risk of severe drowsiness [1.2.2, 1.3.1].
Impaired Alertness: Meclizine can cause significant drowsiness and impair thinking and reaction times; avoid driving until you know how it affects you [1.2.2, 1.3.1].
Pregnancy and Breastfeeding: Use during pregnancy or while breastfeeding should only be done after consulting a healthcare provider [1.3.6, 1.5.1].

Understanding Meclizine and Its Function

Meclizine is a first-generation antihistamine that is widely available both over-the-counter and by prescription to manage nausea, vomiting, and dizziness associated with motion sickness and vertigo [1.2.5, 1.3.2]. It works by blocking histamine H1 receptors and has a marked effect on the vestibular system, which is responsible for our sense of balance [1.3.6, 1.9.1]. While effective for many, meclizine's primary mechanisms also lead to side effects and risks that make it unsuitable for certain individuals. Its anticholinergic properties, which block the neurotransmitter acetylcholine, can interfere with various bodily functions [1.4.3]. The most common side effect is drowsiness, which can impair coordination and alertness [1.2.3]. Therefore, understanding the specific contraindications and warnings is crucial for safe use.

Individuals with Pre-existing Medical Conditions

People with certain health issues must be cautious or avoid meclizine altogether because its anticholinergic effects can worsen their conditions [1.3.5].

Glaucoma: Meclizine can increase pressure within the eye, potentially exacerbating narrow-angle glaucoma [1.3.2, 1.7.1]. Patients may experience sudden eye pain or blurred vision [1.2.6].
Asthma and Respiratory Conditions: As an antihistamine, meclizine can thicken mucus in the lungs, which may worsen breathing problems in people with asthma, emphysema, or chronic bronchitis [1.3.1, 1.3.2, 1.7.3].
Enlarged Prostate and Urinary Issues: The drug can make urination more difficult and may worsen urinary retention, a common issue for men with an enlarged prostate (benign prostatic hyperplasia or BPH) [1.3.2, 1.7.3].
Liver or Kidney Disease: Individuals with hepatic or renal impairment should use meclizine with caution. Since the liver metabolizes the drug and the kidneys excrete it, poor function can lead to accumulation of the drug in the body, increasing the risk of side effects [1.3.1, 1.3.5, 1.4.2].
Phenylketonuria (PKU): Some chewable meclizine tablets contain phenylalanine, which can be dangerous for people with PKU, a rare genetic disorder [1.2.3, 1.3.5].

Specific Age Groups

Age is a significant factor in determining the safety of meclizine use.

Children Under 12: The safety and effectiveness of meclizine have not been established in children under 12 years of age. Therefore, its use is not recommended for this age group without direct medical supervision [1.3.4, 1.9.3, 1.9.4].
Older Adults (65 and Over): The American Geriatrics Society (AGS) recommends that older adults avoid meclizine due to an increased risk of side effects like confusion, dizziness, delirium, falls, and dementia associated with its long-term use [1.4.3, 1.8.1]. Older adults are more sensitive to the drug's anticholinergic effects, which can also cause amnesia and urinary retention [1.4.3, 1.4.6].

Pregnancy and Breastfeeding

While epidemiological studies in pregnant women do not show that meclizine increases the risk of fetal abnormalities, animal studies have shown issues at very high doses [1.3.6, 1.5.6]. It is generally considered safe for treating nausea and vomiting during pregnancy but should only be used if clearly necessary and after consulting a healthcare provider [1.3.6, 1.5.3]. It is not known for sure if meclizine passes into breast milk, and large or prolonged doses could potentially affect the infant or reduce milk supply [1.5.1, 1.5.2].

Critical Drug and Substance Interactions

Combining meclizine with other substances that depress the Central Nervous System (CNS) can dangerously increase side effects like drowsiness, dizziness, and impaired coordination.

Alcohol

Drinking alcohol while taking meclizine significantly enhances its sedative effects and should be avoided [1.2.2, 1.3.1]. The combination greatly impairs the ability to drive or operate heavy machinery safely.

Other Medications

Numerous medications can interact with meclizine, amplifying CNS depression. Patients should inform their doctor if they are taking any of the following [1.3.2, 1.6.2, 1.6.3]:

Sedatives, tranquilizers, or sleeping pills (e.g., zolpidem, eszopiclone)
Opioid pain relievers (e.g., hydrocodone, oxycodone)
Benzodiazepines for anxiety (e.g., alprazolam, diazepam, lorazepam)
Other antihistamines (e.g., diphenhydramine)
Muscle relaxants (e.g., cyclobenzaprine)
Certain antidepressants (e.g., amitriptyline, paroxetine)
Antipsychotics (e.g., quetiapine, olanzapine)
CYP2D6 Inhibitors: Meclizine is metabolized by the liver enzyme CYP2D6. Drugs that inhibit this enzyme (like bupropion or fluoxetine) can increase meclizine levels in the blood, leading to more pronounced side effects [1.2.4, 1.3.2].


Drug Class	Interaction Risk with Meclizine	Potential Side Effects	Example Medications
CNS Depressants	High	Increased drowsiness, dizziness, impaired motor skills [1.2.2]	Alcohol, Opioids, Benzodiazepines [1.3.2, 1.6.2]
Anticholinergics	High	Worsened dry mouth, blurred vision, urinary retention [1.6.1]	Scopolamine, Dicyclomine [1.6.1]
CYP2D6 Inhibitors	Moderate	Increased meclizine blood levels and side effects [1.2.4, 1.6.6]	Bupropion (Wellbutrin), Fluoxetine (Prozac) [1.3.2, 1.6.6]
MAOIs	High	Interaction can prolong and intensify anticholinergic effects [1.3.3]	Isocarboxazid, Phenelzine [1.3.3]

Conclusion

While meclizine is a useful medication for managing symptoms of motion sickness and vertigo, it is not suitable for everyone. Individuals with a history of hypersensitivity to the drug, children under 12, and those with specific medical conditions like glaucoma, asthma, and BPH should avoid it [1.3.1, 1.7.1, 1.9.3]. Older adults are strongly cautioned against its use due to a higher risk of significant side effects, including falls and cognitive impairment [1.4.3, 1.4.5]. Furthermore, the potential for severe drowsiness is amplified when meclizine is combined with alcohol or other CNS depressant medications [1.2.2]. Always consult with a healthcare professional to determine if meclizine is a safe choice based on your health profile and current medications.

For more detailed information from a reliable source, you can visit the Mayo Clinic's page on Meclizine.

Frequently Asked Questions

No, you should avoid drinking alcohol while taking meclizine. The combination can significantly increase drowsiness and other side effects [1.3.1, 1.2.2].

Generally, meclizine is not recommended for adults aged 65 or older. The American Geriatrics Society's Beers Criteria lists it as a medication to avoid in this age group due to a higher risk of confusion, falls, delirium, and cognitive decline [1.4.3, 1.4.5].

People with glaucoma, asthma or other lung diseases, an enlarged prostate, or urination problems should use meclizine with caution or not at all, as it can worsen these conditions [1.3.1, 1.7.1].

Meclizine is not recommended for children under 12 years old because its safety and effectiveness have not been studied in this age group [1.9.3, 1.9.4].

Meclizine interacts with other CNS depressants like sedatives, opioids, benzodiazepines, and other antihistamines, which can worsen drowsiness. It also interacts with drugs that inhibit the CYP2D6 enzyme, like certain antidepressants [1.3.2, 1.6.2].

You should use meclizine with caution if you have liver or kidney disease. These conditions can cause the drug to build up in your body, increasing the risk of side effects. Consult your doctor first [1.3.1, 1.3.5].

No, you should not drive or operate heavy machinery until you know how meclizine affects you. It can cause drowsiness and impair your coordination and reaction time [1.2.2, 1.3.1].