Can You Take Cetirizine with Loratadine?

Last reviewed: · Source: US FDA drug label database

Cetirizine also sold as: Zyrtec, Piriteze · Loratadine also sold as: Claritin, Clarityn

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USE WITH CAUTION

Cetirizine and loratadine do the same job — doubling up gives little extra benefit and more drowsiness; if one isn't working, switching or seeing a GP beats stacking.

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Is it safe to take Cetirizine with Loratadine?

Both are second-generation antihistamines blocking the same H1 receptor. Taking both together is not dangerous in the way some interactions are, but it's rarely useful: benefit plateaus while side effects (drowsiness, dry mouth) add up. If a standard dose of one isn't controlling hay fever or hives, better strategies are switching to the other (people respond differently), adding a steroid nasal spray or eye drops, or seeing a GP — some urticaria patients are prescribed higher antihistamine doses deliberately, but that should be medically supervised.

How do Cetirizine and Loratadine interact?

Both competitively antagonise peripheral H1 receptors. Receptor occupancy from a standard dose of either is already high, so combined use adds little efficacy. Cetirizine has mild CNS penetration (drowsiness in ~10%); additive sedation is the main practical downside. No pharmacokinetic interaction exists.

Data sourced from the US Food and Drug Administration (FDA) drug label database: OpenFDA cetirizine and loratadine labels.

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Who should be careful?

Drivers and machine operators (additive drowsiness), the elderly, people with kidney impairment (both are renally cleared), and children — never double-dose children's antihistamines.

For weight-based or dosage calculations, our dosage calculators can help. If you're tracking what you eat alongside your medication, 247CalorieCheck's food and nutrition checker is worth a look too.

What if I've already taken Cetirizine and Loratadine?

Taking both once won't harm a healthy adult — expect possible drowsiness and skip the next dose of one. For ongoing symptoms, pick one antihistamine and add a different class of treatment rather than a second antihistamine.

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Not sure if this combination is safe for your specific situation?

HealthLabs.com lets you check liver enzyme or kidney function levels before combining medications long-term — no GP referral needed.

Check your levels at HealthLabs →

Always speak to your pharmacist or GP for personalised medical advice. Affiliate link — we may earn a commission.

Frequently Asked Questions

Can I take cetirizine and loratadine together?

It's not dangerous but rarely helpful — they work identically. Switch between them or add a nasal steroid spray instead.

My antihistamine isn't working — what should I do?

Try the other one (responses vary between people), add a steroid nasal spray for hay fever, and see your GP if symptoms persist — supervised higher dosing is possible for hives.

Which is better, cetirizine or loratadine?

They're similarly effective overall. Cetirizine may act slightly faster but causes drowsiness in more people; loratadine is the least sedating.

Can I take one in the morning and the other at night?

There's little benefit — both last 24 hours. If you need round-the-clock control, a single daily antihistamine plus a nasal steroid works better.