The Independent Pharmacy

Claritin Vs Zirtek: What's The Difference?

Daniel Hurley
Daniel HurleyMPharm IPPharmacist Independent Prescriber

Reviewed on 9 May 2024

The main difference between Claritin and Zirtek is what's in them and how likely they are to make you sleepy. Claritin (available as Clarityn or loratadine in the UK) is less sedating, making it better for daytime allergy relief. Zirtek (known as cetirizine or Zirtek on the UK market) works quickly but is more prone to causing drowsiness, so people often take it at night.

In the UK, you’ll see these allergy medications listed as loratadine for Claritin and cetirizine for Zirtek. Brand names like Clarityn and Benadryl Allergy One-A-Day Tablets or Zirtek are the same respective drugs.

Zirtek Allergy Tablets
Zirtek Allergy Tablets
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While both treat hay fever symptoms effectively, their divergent sedating effects make one or the other preferable, depending on your needs.

As your partner in health, we’ll fully compare their effectiveness, side effects, safety, and availability so you can select the ideal allergy relief for your lifestyle.

Key Takeaways

  • Claritin (loratadine) works just as well as Zirtek for treating hay fever symptoms like sneezing, runny noses, and itchy eyes. But it's less likely to make you feel drowsy during the day.
  • Zirtek (cetirizine) starts relieving allergy symptoms super fast, often within an hour. But the NHS says that more than 1 in 10 people feel sleepy as a side effect compared to Claritin (more than 1 in 100 people).
  • Both medications work for 24 hours with just one pill to keep your allergies away all day. But Claritin may provide longer-lasting, non-drowsy symptom control.
  • Claritin and Zirtek are usually safe, but talk to your doctor first if you have kidney or liver issues, are pregnant or breastfeeding, or if you're thinking about giving them to young children.

Claritin vs Zirtekat a Glance


Claritin (Loratadine)


Active Ingredient



Speed of Relief

You can feel relief within an hour

Works super fast, often within 1 hour


Less likely to make you feel sleepy

More likely to make you feel sleepy

Duration of Effect

24 hours with one pill

24 hours with one pill

Best Time to Take

Anytime, as it is less sedating

Better to take at night due to drowsiness

Common Side Effects

Mild drowsiness, dry mouth, headaches

Drowsiness, dry mouth, dizziness, nausea

Safety for Kids

Generally safe but check with a doctor

Not recommended for very young kids under 2

Use with Other Medications

Check with a doctor if you take other medications

Must be careful; interacts with some medications


Tablets, liquid; over-the-counter

Tablets, chewable tablets, liquid; over-the-counter

Considerations for Health Conditions

Check if you have liver or kidney problems

Use with caution if you have kidney problems

Comparing How Well They Work


Claritin (loratadine) does an excellent job at relieving all those miserable allergy symptoms like constant sneezing, itchy/watery eyes that won’t stop bothering you, runny noses, and itchy rashes on your skin. According to 2023 research, it can start helping with hay fever symptoms within an hour.

But here’s the best part - Claritin doesn’t make you feel sleepy or out of it during the day like some other allergy meds might. The NHS states that more than 1 in 100 people feel drowsy after taking loratadine (the active ingredient in Claritin). That non-drowsy formula lets you keep powering through your normal daily routine without that foggy, sluggish feeling holding you back. And just a single pill can provide 24 full hours of steady symptom relief.


Just like Claritin, Zirtek (cetirizine) is super effective against all those lousy allergy symptoms from hay fever, seasonal allergies, or other triggers like pet dander. You know, the constant sneezing fits, the runny noses and itchy eyes that just won’t quit, scratchy throats, and itchy rashes. As for how long hay fever tablets take to work, the effects can vary based on the specific product. Research from 2023 shows it starts working on those symptoms really fast, too, often within an hour.

The only downside is that Zirtek tends to make more people with allergies feel that drowsy, tired feeling as a side effect compared to other hay fever tablets. Based on the NHS, more than 1 in 10 people feel tired after taking cetirizine (the active ingredient in Zirtek). So, while it gets to work quickly, you may need to be careful about taking it during the day when you need to be fully alert.

Winner: Claritin

Claritin is as effective as Zirtek for most hay fever symptoms but has the advantage of not making you feel sleepy. This makes it easier to use during the day or for school and activities.

Clarityn 10mg Allergy Relief
Clarityn 10mg Allergy Relief
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Side Effects and Safety


While Claritin is generally very safe, the NHS guidelines for loratadine warn that more than 1 in 100 people may experience side effects like:

  • Feeling a little drowsy or tired (but less likely than other hay fever meds)
  • Headaches
  • Overall fatigue

It’s usually okay for most adults and kids to take Claritin as long as they follow the dosage instructions. But you should check with your doctor first if you are elderly, have kidney or liver problems (which affect how your body processes the allergy medicine), are pregnant, or are a nursing mother. Taking too much can increase side effects.


Zirtek is also safe for most people. But some common side effects of the active ingredient cetirizine the NHS wants you to watch out for include drowsiness (feeling very sleepy), which affects more than 1 in 10 people.

Other side effects that appear in more than 1 in 100 people are:

  • Dry mouth
  • Dizziness
  • Nausea (feeling sick to your stomach)
  • Headaches

Like Claritin, Zirtek may not be the best choice if you have kidney problems, are an elderly adult, are pregnant or breastfeeding, or give it to really young kids under 2 years old. Please stick to the recommended dosage to prevent increased sleepiness or other potential complications. We're here to help you manage your hay fever symptoms safely and effectively.

Winner: Claritin

Claritin is less likely to make you sleepy compared to Zirtek, making it a safer choice if you need to stay alert for activities or study.

Drug Interactions and Safety Tips


It’s important to be aware of other medications and substances that might interact with loratadine (Claritin), as we want to ensure you experience effective and safe relief from your symptoms. The NICE's list of loratadine interactions includes:

  • Certain antidepressants
  • Sedatives
  • Antibiotics like erythromycin
  • Drinking alcohol

Safety tips when taking Claritin:

  • Do not take more than the recommended dose
  • Avoid operating heavy machinery if drowsiness occurs
  • Speak to your doctor about using caution if you have liver or kidney disease
  • Let your doctor know about all other medications you’re taking


Like Claritin, cetirizine (Zirtek) can interact with some other drugs and substances, potentially causing adverse effects. The list of cetirizine interactions from the NICE includes:

  • Antidepressants
  • Sedatives/sleep medications
  • Antibiotics
  • Alcohol consumption

Key safety advice for Zirtek users:

  • Take only the prescribed dose, no more
  • Avoid driving or using big machines until you're sure the medicine doesn’t make you sleepy
  • Tell your doctor about all the medicines you take, even ones you can buy without a prescription
  • Be cautious if you have liver or kidney problems

Following dosage instructions and your doctor’s guidance is crucial for the safe use of Zirtek or any antihistamine medication.

Winner: Claritin

Claritin has fewer drug interactions, making it a safer choice if you are already taking other medications.

Availability and Forms


You’ll find the non-drowsy antihistamine Claritin (loratadine) readily available over-the-counter in a variety of convenient forms across the UK. Oral tablet formats make taking a once-daily dose easy - simply swallow one pill to get long-lasting 24-hour hay fever relief.

For children, Claritin also comes as a syrup, which you can measure out with the provided cup or syringe. This may require taking doses more frequently throughout the day.

No matter which form you choose, you’ll find the active ingredient loratadine sold under the familiar brand name Clarityn at pharmacies all across the UK.


The fast-acting antihistamine Zirtek (cetirizine) gives you plenty of choices when it comes to what form to take. You can purchase it as a traditional swallowable tablet for once-daily dosing. You can also get an oral cetirizine solution if you prefer liquids over pills. And if you need allergy relief for children, there is also a flavoured Piriteze syrup.

While the dosage schedule may vary slightly depending on the specific product, all these Zirtekforms will start relieving your allergic symptoms like sneezing, stuffy nose, and itchy eyes quickly - often within an hour.

You’ll recognise UK brand names like Benadryl Allergy, Piriteze, and Zirtek as products containing the active cetirizine ingredient when shopping at your pharmacy.

Winner: Tie

Both Claritin and Zirtek are available in various forms, like tablets and syrups, making them both accessible and easy to take.

Choose the Right Medication for You

When it comes to choosing between Claritin (loratadine) and Zirtek (cetirizine) for your hay fever relief needs, the main factor to consider is how their effects on causing drowsiness match up with your daily routine.

If you need an antihistamine that won’t make you feel sleepy during work, school, or other daytime activities, then non-drowsy Claritin may be the better option for you. Its loratadine ingredient effectively treats allergy symptoms while allowing you to stay alert.

However, if you don’t mind feeling a little drowsy and can take your medication at night, then you may prefer Zirtek. Its cetirizine formula starts relieving sneezing, runny noses, itchy eyes, and other kinds of allergic reactions in people very quickly - often within an hour. But that fast relief comes with a higher chance of sedation side effects.

No matter which you choose, always follow the dosage instructions carefully. Both come in convenient tablet formulas that provide long-lasting 24-hour relief, and understanding what affects the pollen count can help you plan the best times to take the hay fever pills. Liquid forms like syrups and solutions are also available if you prefer those over pills.

If you’re unsure which antihistamine would be better for your specific allergic conditions and lifestyle or are planning a trip and wondering if you can get hay fever on holiday, don’t hesitate to ask your pharmacist for personalised guidance. With their expertise, you can make the most informed choice.

Take the Next Step With The Independent Pharmacy

Now that you understand the key differences between Claritin and Zirtek, it’s time to find the perfect hay fever relief medication for your needs. The Independent Pharmacy makes it easy to get started.

First, visit our website and complete a simple online self-assessment about your hay fever symptoms. Answer a few questions like how often you experience a runny nose, sneezing, itchy eyes, or other issues. This helps our pharmacy team understand your unique situation.

After you submit the assessment, we’ll evaluate your responses and get back to you with personalised recommendations. Depending on the severity of your hay fever and daily routines, we may suggest branded options like Clarityn (loratadine) or Benadryl Allergy (cetirizine). Or generic medications containing the same core ingredients could be a more affordable choice.

If you need any additional guidance, contact one of our pharmacists. We are just a phone call away. We’re happy to answer all your questions and help you understand how to properly take your medication for maximum benefits with minimal adverse events. And to learn more about your medical condition, give a read to our hay fever guides.

Ready to kiss allergy symptoms goodbye? Just visit our website today and start your self-assessment. Taking that first step connects you with effective, personalised hay fever treatments from The Independent Pharmacy.


Which antihistamine is the most effective?

There’s no single “most effective” antihistamine that works best for everyone. Claritin and Zirtek are two of the most popular and effective choices. But what matters most is finding the specific medication that works well with your body.

Which is better, cetirizine or loratadine?

Cetirizine is the active ingredient in Zirtek, while loratadine is what makes Claritin work. They’re equally good at treating allergies overall. Cetirizine (Zirtek) just has a bit quicker onset of action but can also make some people feel sleepier.

Who should not take Zirtek?

You may need to avoid Zirtek if you have kidney problems or trouble filtering out waste from your body. It’s also important to check with your healthcare provider about Zirtek if you’re taking other medications like antibiotics, as they could negatively interact.

Who should not take Claritin?

If you have liver disease, it's important to avoid Claritin, as it could affect how your body processes the medication. Your well-being is our top priority, so please consult with your healthcare provider for alternatives that are safe and effective for you. Also, be cautious with Claritin if you’re pregnant, breastfeeding, or taking certain antidepressants. Your doctor or pharmacist can advise if Claritin is safe for your situation.


NHS (2021). Loratadine -

NHS (2021). Cetirizine -

Gursharan Sidhu; Hossein Akhondi (2023). Loratadine -

Aasim Naqvi; Valerie Gerriets (2023). Cetirizine -

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