Can I take antihistamines with alcohol?
Drug interaction guide
Originally published 30 Apr 2026
Meets Patient’s editorial guidelines
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Combining alcohol with antihistamines can make you feel extremely drowsy, dizzy, and unsteady on your feet. It can also slow down your breathing and significantly impair your coordination and judgement. This effect is much stronger with older 'sedating' antihistamines (like chlorphenamine or promethazine), but it can also happen with newer 'non-drowsy' versions (like cetirizine or loratadine).
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Why this happens
Both alcohol and antihistamines act as 'depressants' on the central nervous system. This means they both slow down brain activity. When taken together, they have an 'additive effect', meaning they reinforce each other's side effects, making the sedation much more powerful than if you took either one alone.
What you should do
Back to contentsIt is best to avoid or strictly limit alcohol when taking any antihistamine. Do not drive, operate machinery, or perform tasks that require you to be alert if you have consumed alcohol while taking this medication. If you are taking an older, sedating antihistamine (often found in night-time cold and flu remedies), you should avoid alcohol entirely.
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Important precautions
Back to contentsCentral Nervous System Depression
Combining alcohol with antihistamines (especially older types like chlorphenamine or promethazine) significantly increases drowsiness, impairs coordination, and can dangerously slow your breathing. Do not drive or operate machinery if using both.
Glaucoma and Urinary Retention
Sedating antihistamines can worsen narrow-angle glaucoma and cause severe difficulty passing urine, particularly in men with an enlarged prostate.
Food and drink warnings
Back to contentsFruit Juices (Grapefruit, Orange, Apple)
Do not drink grapefruit, orange, or apple juice while taking fexofenadine. These juices can significantly reduce the amount of medicine your body absorbs, making the treatment less effective. It is best to take fexofenadine with water.
More about Fexofenadine (Allegra)
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Using other medicines
Back to contentsTaking multiple medicines? Our Medicines Interaction Checker helps you check whether your prescriptions, over-the-counter medicines, and supplements are safe to take together. Simply search for your medicines to see potential interactions and what to do about them.
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Using cannabis while taking clozapine can significantly change the levels of the medicine in your blood. It can also increase the risk of serious side effects like extreme drowsiness, confusion, and heart problems. If you stop or start smoking cannabis suddenly, your clozapine levels could become dangerously high or too low, potentially leading to a relapse of your symptoms or severe toxicity.
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Article history
The information on this page is written and peer reviewed by qualified clinicians.
30 Apr 2026 | Originally published
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