Zyrtec vs Claritin vs Allegra: which allergy medicine is best?
Zyrtec, Claritin and Allegra are the three most popular second-generation (“non-drowsy”) oral antihistamines for hay fever and hives. All three are once-daily, available over the counter and as low-cost generics, and work in similar ways — so the right pick usually comes down to how fast it works, how likely it is to make you sleepy, and how your body responds.
There is no single “best” — for typical seasonal allergies the three are broadly comparable. Cetirizine (Zyrtec) often works fastest but is the most likely of the three to cause some drowsiness; loratadine (Claritin) and fexofenadine (Allegra) are the least sedating and comparably non-drowsy — fexofenadine absorbs best on an empty stomach and shouldn't be taken with fruit juice.
| Zyrtec cetirizine | Claritin loratadine | Allegra fexofenadine | |
|---|---|---|---|
| Active ingredient | Cetirizine Hydrochloride | Loratadine | Fexofenadine Hydrochloride |
| Our rating | Not yet rated | 68/100 | Not yet rated |
| Pharmacy pays | No data | ~$1.59 /30 | ~$7.33 /30 |
| Onset | ~1 hour (often the fastest) | 1–3 hours | ~1–2 hours |
| Drowsiness | Low — but the most likely of the three to cause some | Low — non-sedating, on par with Allegra | Non-drowsy |
| Good to know | A good choice when you want quick relief; a minority of people feel mild sleepiness. | Best when staying fully alert is the priority; onset can be a little slower. | Take with water (not fruit juice, which lowers absorption), ideally on an empty stomach. |
Ratings are our independent FDA recall-safety score. General information, not medical advice.
Which should you choose?
Zyrtec (cetirizine)
A good choice when you want quick relief; a minority of people feel mild sleepiness.
Claritin (loratadine)
Best when staying fully alert is the priority; onset can be a little slower.
Allegra (fexofenadine)
Take with water (not fruit juice, which lowers absorption), ideally on an empty stomach.
All three relieve sneezing, runny nose, itchy/watery eyes and hives, and per MedlinePlus they share the same second-generation antihistamine class with a low risk of the heavy sedation seen with older antihistamines. Pick by practical fit: reach for Zyrtec (cetirizine) if you want the fastest relief and don't mind a small chance of drowsiness; Claritin (loratadine) if staying fully alert matters most; Allegra (fexofenadine) for reliably non-drowsy relief (take it with water, not juice, ideally on an empty stomach). If one doesn't work well for you, it's reasonable to try another — response varies by person. This is general information, not medical advice; ask a pharmacist or doctor if you're pregnant, take other medicines, or have a health condition.
Frequently asked questions
Which is the strongest — Zyrtec, Claritin or Allegra?
For everyday seasonal allergies they relieve symptoms similarly; studies don't crown a clear winner. Some people find cetirizine (Zyrtec) feels strongest/fastest, but it is also the most likely to cause mild drowsiness. “Strongest” for you is the one that controls your symptoms with side effects you can live with.
Which allergy medicine is least likely to make you drowsy?
Loratadine (Claritin) and fexofenadine (Allegra) are the least sedating; fexofenadine is considered truly non-drowsy. Cetirizine (Zyrtec) is still far less sedating than older antihistamines like diphenhydramine, but is the most likely of these three to cause drowsiness in some people.
Can you take them together?
You should not double up on antihistamines without medical advice — taking two at once adds side-effect risk without proven extra benefit. If one isn't controlling your symptoms, ask a pharmacist before combining or switching.
Are the store-brand generics the same?
Yes. The FDA requires generic cetirizine, loratadine and fexofenadine to have the same active ingredient, strength and effect as the brand — usually at a much lower price.