Can I mix alcohol and antihistamines if I need to drive and stay alert this evening?

Short answer

Why people ask this

Drivers who plan to be behind the wheel later often wonder whether a single drink with their allergy pill is okay. Evening social plans can involve alcohol, but safe driving still requires full alertness and quick reactions. Antihistamines—especially first‑generation products—can cause drowsiness on their own, and alcohol magnifies that effect. Even so‑called “non‑drowsy” antihistamines can subtly slow reaction time when combined with alcohol, which matters a lot in night traffic and glare.

When it might be safe

There are no commonly accepted situations where this is considered safe.

When it is not safe

• Additive sedation and slowed reaction time make evening and night driving riskier, even with a single drink.
• First‑generation antihistamines (e.g., diphenhydramine, chlorpheniramine) plus alcohol can cause impaired lane-keeping and delayed braking.
• Second‑generation “non‑drowsy” options (cetirizine, levocetirizine, loratadine) may still impair alertness when mixed with alcohol—problematic for dusk/night driving.
• Long-acting antihistamines taken earlier may still be active by evening; adding alcohol before a drive increases impairment duration.
• You can be unsafe or legally impaired for driving even below the legal BAC if medications contribute to diminished driving ability.

Possible risks

• Microsleeps, poorer attention to changing traffic lights, and difficulty with night glare.
• Slower hazard detection and delayed braking, increasing crash risk at intersections and during sudden stops.
• Dizziness, blurred vision, and impaired coordination when merging or making quick lane changes.
• Nausea or orthostatic lightheadedness when standing up to leave and starting the drive.
• Greater impairment on field-sobriety tasks (balance, tracking) despite a low BAC.

Safer alternatives

• If you must drive this evening, skip alcohol entirely; take only a non-sedating antihistamine as directed, or delay any sedating dose until you’re home for the night.
• Prefer non-sedating daytime options (e.g., fexofenadine or loratadine) taken alone; avoid first‑generation antihistamines if driving later.
• Use non-alcohol alternatives at the event and plan a designated driver or rideshare if you want to drink.
• Consider non-sedating symptom control: intranasal steroid sprays, saline rinses, or topical treatments for localized itch.
• If you already took a sedating antihistamine (e.g., diphenhydramine), avoid alcohol and arrange a sober ride for the evening.
• Time your medication earlier in the day (per label) and reassess symptoms before the evening drive instead of adding alcohol.

Bottom line

For anyone who needs to drive and stay alert this evening, do not mix alcohol with antihistamines. Even small amounts together can meaningfully impair night-driving performance and increase crash risk.

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