The standard dose of loratadine is 10 mg once a day for adults and children age 6 and older. You should not take more than 10 mg in a 24-hour period. This applies whether you’re taking tablets, chewable tablets, dissolving tablets, liquid-filled capsules, or the liquid syrup form.
Adult and Child Dosing
For adults, the dose is straightforward: one 10 mg tablet (or equivalent) once daily. Children 6 and older follow the same 10 mg dose, though kids under 6 or those weighing 30 kg (about 66 pounds) or less should use the liquid form instead of tablets. For younger children, a doctor will calculate the right amount based on the child’s weight or age.
How Long It Takes to Work
Loratadine starts working within 1 to 3 hours of taking it, with its strongest effects kicking in between 8 and 12 hours. The drug itself has a half-life of about 8 hours, but it breaks down into an active compound that stays in your system for roughly 28 hours. This is why once-daily dosing is enough for most people, and why taking a second dose the same day won’t help much. You’re already getting close to round-the-clock coverage from a single pill.
What Happens if You Take Too Much
Loratadine is a second-generation antihistamine, which means it’s designed to cause less drowsiness than older allergy medications like diphenhydramine (Benadryl). That said, taking significantly more than the recommended dose still carries real risks. Antihistamine overdose can cause drowsiness, rapid heart rate, blurred vision, and in serious cases, seizures or dangerous heart rhythm changes. Neurological symptoms tend to appear within about two hours of ingestion.
If you accidentally take a double dose, you’re unlikely to experience serious harm from 20 mg, but don’t make it a habit. If you’ve taken substantially more than the recommended amount, or if a child has gotten into the medication, contact poison control or seek medical attention.
If You’re Breastfeeding
Loratadine is considered one of the safer antihistamine choices during breastfeeding. At the standard 10 mg dose, very little of the drug passes into breast milk. A study of 51 breastfeeding mothers who took loratadine found no differences in infant sedation or other side effects compared to mothers who didn’t take it. The British Society for Allergy and Clinical Immunology lists loratadine at its lowest effective dose as a preferred option for nursing mothers who need an antihistamine.
One note: a single mother in that study reported decreased milk supply after taking 10 mg daily for less than a week. This is rare and wasn’t seen across the broader group, but it’s worth being aware of.
When 10 mg Isn’t Enough
If your allergies aren’t well controlled on 10 mg of loratadine, taking more isn’t the answer. Instead, you can add a different type of allergy treatment: a nasal corticosteroid spray, eye drops for itchy eyes, or a different class of antihistamine at a different time of day. Some people also find that switching to a different second-generation antihistamine like cetirizine or fexofenadine works better for their symptoms, since individual responses vary. Your pharmacist can help you figure out what’s safe to combine.