Loratadine, cetirizine, and fexofenadine are three of the most widely used OTC allergy medicines in the United States. You may know them better by their brand names: Claritin, Zyrtec, and Allegra.
All three are second-generation antihistamines. All three are taken once daily. All three are designed to relieve sneezing, runny nose, itchy eyes, and other common allergy symptoms with significantly less drowsiness than older options like diphenhydramine (the active ingredient in Benadryl).
So how do you choose between them? Here is a plain-English breakdown that a pharmacist would give you across the counter.
What all three have in common
Each of these three medicines:
- Blocks the same kind of receptor (H1 histamine) that drives allergy symptoms.
- Is taken once every 24 hours at standard adult doses.
- Is available as a generic at a fraction of the brand-name price.
- Has a well-established safety record from decades of widespread use.
- Comes in tablet, liquid, and dissolving forms (varies slightly by brand).
For mild seasonal allergy symptoms in a healthy adult, any of the three is a reasonable starting point. The differences matter more for stronger symptoms, drowsiness sensitivity, or specific lifestyle factors.
The differences that matter
Strength of effect
In general, cetirizine tends to feel a bit stronger than loratadine or fexofenadine for many people. If you've tried loratadine and felt like it didn't quite cover your symptoms on the worst pollen days, cetirizine is often the next thing to try.
Loratadine and fexofenadine are roughly comparable to each other for mild to moderate symptoms, with fexofenadine generally seen as a strong everyday option and loratadine as the most-used baseline.
Drowsiness
Drowsiness risk is a real consideration if you drive, work, or care for kids during the day. Here's how the three compare:
- Fexofenadine has the lowest drowsiness rate. In studies, sedation has been found to be similar to placebo at standard doses in healthy adults. This is often the best choice for people who can't afford any compromise in alertness.
- Loratadine is also classified as a non-drowsy antihistamine. Most people tolerate it at the 10 mg adult dose without meaningful drowsiness.
- Cetirizine is the most likely of the three to cause mild drowsiness in some people. It's still significantly less sedating than first-generation antihistamines, but a small percentage of users notice mild fogginess, especially when starting.
How quickly they work
All three typically begin working within one to three hours of the first dose. For long-term daily use, the small differences in onset speed don't matter much, what matters is that you take the medicine consistently so the protection is in place before allergens hit.
How long they last
All three are designed for 24-hour coverage with one dose per day. Some people notice their symptoms returning slightly before the next dose, particularly during high-pollen days. If that happens, talk to a pharmacist about timing and any other steps you can add, a daily nasal spray often helps as a second layer.
The fexofenadine fruit-juice note
One practical detail worth knowing: fexofenadine absorption is reduced by certain fruit juices, including grapefruit, orange, and apple juice. Taking fexofenadine with water rather than juice keeps the absorption where it should be. If you usually drink juice in the morning when you take your daily allergy medicine, this is worth knowing before you build the habit.
Loratadine and cetirizine don't have this fruit-juice interaction.
Quick comparison
| Loratadine | Cetirizine | Fexofenadine | |
|---|---|---|---|
| Brand name | Claritin | Zyrtec | Allegra |
| Strength of effect | Moderate | Often the strongest of the three | Moderate |
| Drowsiness profile | Very low | Low to mild | Extremely low |
| Best for | Everyday mild to moderate symptoms | Stronger or persistent symptoms | Maximum non-drowsy daily use |
| Fruit juice note | No interaction | No interaction | Take with water only |
| Once daily | Yes | Yes | Yes |
Which one should you choose?
A simple way to think about it:
- Start with loratadine if you've never used a daily antihistamine. It's the most predictable starting point with a long track record.
- Try cetirizine next if loratadine isn't strong enough, and mild sedation isn't a deal-breaker for your routine.
- Try fexofenadine if you need the cleanest non-drowsy profile possible, or if any sedation from cetirizine bothers you.
If you've tried more than one and still aren't getting enough relief, the next step is usually adding a daily nasal spray (like fluticasone) rather than switching antihistamines again. Multiple layers often work better than a stronger single layer.
What about combining them
Don't take two oral antihistamines at the same time. They work on the same receptor, and doubling up doesn't double the effect, it usually just doubles the side effects, especially drowsiness.
What does work well is layering different types of allergy products: an oral antihistamine plus a nasal spray plus saline rinse, for example. These all target the problem differently, so they can work together. A pharmacist can help you build a sensible daily routine if you're not sure where to start.
When to talk to a pharmacist before choosing
Worth a quick call before you order if any of these apply:
- You're pregnant or breastfeeding.
- You take prescription medications, especially for blood pressure, thyroid, or depression.
- You have liver or kidney concerns.
- You're choosing for a child under 6.
- You've had unusual reactions to allergy medicines in the past.
Otherwise, all three are widely used, well-tolerated daily allergy options. You can compare loratadine, cetirizine, and fexofenadine side by side in the Breathe Easy Defense collection, with the same active ingredients as the brand names at honest prices.