Loratadine is an over-the-counter antihistamine used to relieve symptoms of seasonal allergies and to treat chronic hives. Sold under the brand name Claritin (among others), it’s approved for adults and children aged 2 and older. It belongs to the second generation of antihistamines, meaning it controls allergy symptoms without the heavy drowsiness that older options like diphenhydramine (Benadryl) are known for.
Seasonal Allergy Relief
Loratadine’s primary use is treating seasonal allergic rhinitis, commonly called hay fever. It targets both nasal symptoms (sneezing, runny nose, congestion) and non-nasal symptoms (itchy, watery eyes). People typically reach for it during spring and fall when pollen counts spike, but it works against any airborne allergen triggering a histamine response, including dust mites, mold spores, and pet dander.
When your body encounters an allergen, immune cells release histamine, a chemical that triggers inflammation. Histamine activates receptors in your nasal passages and eyes, increasing mucus production, making blood vessels leak fluid, and stimulating the sensory nerves that cause itching and sneezing. Loratadine works by blocking those receptors before histamine can activate them, preventing the cascade of symptoms rather than just masking them.
Treatment for Chronic Hives
Beyond allergies, loratadine is specifically approved for chronic idiopathic urticaria, the medical term for recurring hives with no identifiable cause. These are the red, raised, intensely itchy welts that appear on the skin and can persist for six weeks or longer. Because the same histamine pathway drives hives, blocking the receptor calms the itching and reduces the size and number of welts. For people dealing with hives that come and go unpredictably, a daily dose of loratadine can keep symptoms manageable.
Why It Causes Less Drowsiness
Older antihistamines like diphenhydramine cross freely into the brain, where they block histamine receptors involved in wakefulness. That’s why they make you sleepy. Second-generation antihistamines like loratadine were specifically designed to be more selective: they block histamine receptors in the nose, eyes, and skin without easily penetrating the blood-brain barrier. The result is similar allergy relief with far fewer central nervous system side effects. Most people taking loratadine don’t experience meaningful drowsiness, which is why it’s often preferred by people who need to drive, work, or stay alert during the day.
How Quickly It Works
Loratadine isn’t instant relief. In controlled studies where adults were exposed to ragweed pollen, significant improvement in nasal and eye symptoms began at about 75 minutes after taking a tablet. That relief remained consistent and durable for the rest of an 8-hour observation period. This makes loratadine a good option for daily maintenance during allergy season rather than a rescue medication for sudden symptoms. Taking it in the morning gives it time to reach effective levels before you encounter allergens during the day.
A single 10 mg dose covers a full 24 hours, so once-daily dosing is standard. Unlike short-acting antihistamines that wear off every 4 to 6 hours, loratadine provides steady coverage without redosing.
Standard Dosing
The typical adult dose is 10 mg once a day, whether taken as a regular tablet, chewable tablet, dissolving tablet, or liquid capsule. You should not exceed one dose per day. For children aged 2 to 5, the dose is 5 mg (one teaspoon of the liquid form) once daily. Children 6 and older follow the adult dose of 10 mg.
Loratadine is available in several forms: standard tablets, chewable tablets, orally disintegrating tablets that dissolve on the tongue without water, liquid-filled capsules, and a liquid solution. The dissolving tablets are particularly convenient if you don’t have water handy or have difficulty swallowing pills.
People with significant liver or kidney problems need a different schedule. If you have liver disease or severely reduced kidney function, the recommended starting dose is 10 mg every other day instead of daily. For children aged 2 to 5 with those conditions, the adjusted dose is 5 mg every other day.
Side Effects
Loratadine is well tolerated by most people. Its side effect profile in clinical trials was close to placebo, meaning the medication caused minimal additional symptoms compared to a sugar pill. The most commonly reported effects include mild headache, dry mouth, and fatigue, though these occur at low rates. Significant drowsiness is uncommon at the standard 10 mg dose, which is one of the main reasons it replaced older antihistamines as a first-line allergy treatment.
Pregnancy and Breastfeeding
Loratadine is one of the antihistamines most commonly discussed in the context of pregnancy, and major health agencies like the NHS provide guidance on its use during this time. Small amounts do pass into breast milk, but side effects in breastfed infants are very rare. If you’re nursing and taking loratadine, the main things to watch for are unusual sleepiness, irritability, or changes in your baby’s feeding patterns. If you’re pregnant or trying to conceive, it’s worth discussing the choice of antihistamine with a pharmacist or doctor, though there’s no current evidence that loratadine affects fertility in men or women.
What Loratadine Does Not Treat
Loratadine relieves symptoms caused by histamine, but it won’t help with congestion from a cold or sinus infection, since those involve different inflammatory pathways. It also won’t treat asthma on its own, though some people with allergic asthma use it alongside other medications to reduce their overall allergen response. For nasal congestion specifically, some formulations combine loratadine with pseudoephedrine (sold as Claritin-D), which adds a decongestant to address stuffiness that loratadine alone may not fully resolve.