Can You Take Cetirizine with Loratadine?
Last reviewed: · Source: US FDA drug label database
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.
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.
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.
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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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.