The Independent Pharmacy

Fexofenadine Vs Cetirizine: What's The Difference?

Scott McDougall
Scott McDougallMPharmDirector & Registered Manager

Reviewed on 7 May 2024

When it comes to fexofenadine vs cetirizine, the biggest difference lies in how they can make you feel.

Fexofenadine, often sold as Telfast or Treathay, is known as the “non-drowsy” antihistamine, letting you go about your day without feeling sluggish or sleepy. Cetirizine (Zirtek), on the other hand, is more likely to cause drowsiness as it helps you manage hay fever symptoms.

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Both hay fever medications help stop symptoms like sneezing, runny noses, and itchy eyes. They’re also useful for getting relief from itchy skin rashes and chronic hives. However, feeling drowsy from hay fever medicine can be particularly challenging for those who need to stay sharp and focused at work or school. That’s where fexofenadine really shines.

At the same time, cetirizine can provide a faster onset of action. So, it could be a better fit if you need quick symptom control and don’t mind the sleepy side effects.

Let’s dive into the details to help determine if fexofenadine or cetirizine could be the allergy relief you’ve been searching for.

Fexofenadine vs Cetirizine at a Glance

Feature Fexofenadine Cetirizine
Brand Names Telfast, Treathay Zirtek
Drowsiness Less likely to cause drowsiness, good for staying alert. More likely to cause drowsiness, which could be disruptive.
Onset of Action 1-2 hours Up to 1 hour
Dosage for Adults and Children over 12 One 180mg tablet per day. One 10mg tablet per day
Dosage for Children 6-11 One 30mg tablet per day. One 5mg tablet per day
Common Side Effects Headaches, upset stomach, dizziness. Rarely, serious allergic reactions. Drowsiness, dry mouth, dizziness, nausea, muscle aches. May also cause chest pains or irregular heartbeats in rare cases
Drug Interactions Avoid antacids with aluminium or magnesium, and grapefruit or orange juices. Avoid sleeping pills, anxiety medications, certain antidepressants, and alcohol to reduce drowsiness
Safety for Daily Activities Ideal for those who need to stay alert (e.g., drivers, students). Caution advised if you need to stay alert, as drowsiness is common

Key Takeaways

  • Fexofenadine is less likely to cause drowsiness, great for staying alert during the day
  • Cetirizine may provide faster relief for sudden allergy flare-ups but can make you feel sleepy
  • Fexofenadine is less likely to cause problems when taken with other medications

Dosage Recommendations


According to the Patient Information Leaflet, adults should take one 180mg fexofenadine tablet each day. It’s important not to take more than that 180 mg dose within 24 hours.

Older adults may need to adjust their fexofenadine dose slightly, especially if they have kidney issues that make it harder for their bodies to process the medication effectively. Your healthcare provider can guide you on the proper amount.


For adults dealing with seasonal allergies, the usual dose of cetirizine is just one 10mg tablet daily, as per the Patient Information Leaflet. This tablet helps you ease your symptoms without overwhelming your system. Don’t take more than 10mg in a 24-hour period to prevent drowsiness or other side effects.

For kids between 6-11 years old, the recommended cetirizine amount is just one 5mg tablet daily. This lower child dose helps avoid adverse reactions.

So, when should you take hay fever tablets like cetirizine?

If you’re taking cetirizine in the morning, that drowsy feeling may wear off by evening. Or you can take the full 10mg dose at bedtime to sleep through allergy symptoms without daytime grogginess.

No matter your age, start with the lowest effective dose first when taking a new antihistamine. See how your body tolerates it before increasing the amount gradually if needed. And don’t exceed the maximum daily dose recommended for your specific age and health status.

Side Effects


The biggest benefit of fexofenadine is that it’s what they call a “non-drowsy” antihistamine. Most people can take it without feeling that knocked-out, sedated feeling that some other hay fever tablets cause.

The NHS says fexofenadine tablets can still potentially cause for more than 1 in 100 people some mild side effects like:

  • Headaches
  • Upset Stomach
  • Dizziness

But these aren’t as common, especially if you stick to the regular 180 mg dose.

In very rare cases, fexofenadine may lead to more serious allergic reactions like trouble breathing, swelling of the face/lips/tongue, or a rash on the skin. These adverse events are extremely uncommon, though.

Overall, a 2023 analysis confirms that fexofenadine tends to be easy on most patients without majorly impacting their daily functioning or level of alertness. That makes it a great option for students, workers, drivers - anyone who needs to stay sharp.


Cetirizine is super effective at relieving hay fever symptoms like runny noses and itchy eyes. Unfortunately, drowsiness is one of the more common side effects that often come along with it.

Some people just get a little tired feeling, while others may feel pretty sedated and out of it, especially if taking a higher dose of cetirizine.

Other potential side effects a 2012 study highlights include:

  • Dry mouth
  • Dizziness
  • Nausea
  • Muscle aches or cramps

In rare cases, it could possibly cause more concerning issues like chest pains, irregular heartbeats, or blurred vision.

If you find that cetirizine makes you too drowsy to manage school, work, or other daily activities, it's important to consider alternative options that won't disrupt your day. Be sure to talk to your doctor or pharmacist about adjusting the dose or switching medications if the side effects are too much.

Drug Interactions and Safety


When taking fexofenadine tablets, it’s important to avoid certain other medicines that could diminish its therapeutic efficacy or cause adverse effects.

Here are some of the interactions you should be aware of according to the NICE:

  • Antacids (meds for indigestion and heartburn) containing aluminium or magnesium can actually decrease the amount of fexofenadine absorbed into your system. So it’s best to avoid taking those within 2 hours before or after your fexofenadine dose.
  • Grapefruit and orange juices can also potentially impact how well fexofenadine works by affecting its absorption. It’s not a major interaction for most people, but something to be aware of.

Fexofenadine is generally safe, but make sure to disclose all medications and supplements you’re taking to avoid potential issues.


The NICE list of interactions recommends you avoid taking cetirizine with sleeping pills or anxiety medications, as they can make you even sleepier. Avoid alcohol, too, as it can increase the sedative effects.

Taking cetirizine with certain antidepressants, muscle relaxants, or painkillers can increase side effects. You're more likely to feel very drowsy or uncoordinated.

It's generally safe to use alongside other over-the-counter treatments like pain meds and decongestants, helping you tackle multiple symptoms and find some comfort. Just get your pharmacist's approval on any new additions.

As with any medication, review your full list with your doctor or pharmacist before starting cetirizine. They can identify any risky combinations to avoid.

Managing Drowsiness


The great thing about fexofenadine is it’s considered a “non-drowsy” antihistamine. Most people can take it without feeling sleepy or out of it at all.

Whether you’re at work, school, or just running errands, fexofenadine allows you to stay sharp and focused. It controls allergy symptoms without making you feel foggy or sluggish.

A 2019 analysis of medical studies shows the majority of people don’t experience any drowsiness from fexofenadine. You can take the typical 180mg dose and maintain your normal energy levels throughout the day.


With cetirizine, drowsiness is much more common, appearing in more than 1 in 100 people according to the NHS. The level can range from just a little tired feeling to feeling pretty sedated and out of it.

If you take your full cetirizine dose in the morning, you may feel that drowsy effect hang around all afternoon. This can really disrupt your day when you need to be productive.

One option is taking just half the dose in the morning and the other half at night before bed. Or you could take the full dose at bedtime so you can sleep through the peak drowsiness period.

No matter what, talk to your doctor if the cetirizine drowsiness is really bothering you. They can recommend dose adjustments or a different allergy medication.

Fexofenadine vs Cetirizine: How to Choose the Right One for You?

When it comes to deciding between fexofenadine and cetirizine for your hay fever relief needs, there are a few key factors to consider:

First, think about your daily schedule and lifestyle. If you absolutely have to stay awake and productive for work, school, driving or other activities, then fexofenadine tablets are probably the smarter choice. It could be a good option even for those who need to deal with hay fever on a holiday. Its non-drowsy formula means you can control unpleasant symptoms of allergies without feeling sedated or impaired.

However, if getting fast, effective allergy relief is the top priority - even if it makes you a bit tired - then cetirizine may be better. Many patients report it works more quickly to stop sudden flare-ups of sneezing, runny noses, and itchy eyes compared to fexofenadine.

You’ll also want to consider any other medications you’re taking regularly. Fexofenadine has fewer documented drug interactions, so it could be safer if you’re already on various prescriptions or over-the-counter meds.

If you have kids, make sure to check which child-friendly formations are available as well. Both medications come in formulas designed to be easier and safer for little ones.

Take the Next Step With The Independent Pharmacy

If you’re still unsure whether fexofenadine or cetirizine could be the better allergic symptom relief option for you, don’t worry! The Independent Pharmacy is here to help.

A good first step is to read through our hay fever guides so you understand your options and condition better. When you're ready to get a treatment, fill out a quick self-assessment about your symptoms, such as a runny or itchy nose, itchy eyes, and sneezing.

After you fill that out, one of our pharmacists will personally review your responses. We’ll then get back to you with a customised list of recommended treatments. This could include guidance on whether a non-drowsy medication like fexofenadine or an option like cetirizine may work best.

You can also give us a call or send a message if you have any other questions. Our pharmacy team is happy to listen to your needs and provide one-on-one advice for managing allergies, from medications to avoiding triggers.

No matter what, we’ll work closely with you to implement a comprehensive plan for long-lasting hay fever relief tailored to your lifestyle. Contact our team today. The Independent Pharmacy has your back!


Is fexofenadine stronger than cetirizine?

Not necessarily. Both hay fever drugs are effective antihistamines, but they work a bit differently. Fexofenadine is less likely to cause drowsiness in patients, while cetirizine may relieve some people’s allergy symptoms faster. They have similar overall efficacy when used as directed.

Is fexofenadine the strongest antihistamine?

No, there are other prescription antihistamines that may be considered more potent than fexofenadine in terms of blocking histamine’s effects. However, “strongest” doesn’t always mean “best” - fexofenadine is very effective for most patients while avoiding sedating side effects.

Can I take cetirizine and fexofenadine together?

It’s generally not recommended to take both cetirizine and fexofenadine at the same time. They are similar oral antihistamine medications, so taking them together puts you at a higher risk of increased side effects without adding extra benefits. Stick to one or the other as prescribed.

Should I take fexofenadine at night or morning?

Either time can work, but most people prefer taking their daily fexofenadine dose in the morning. Since it’s non-drowsy, you can take it without worrying about feeling sedated during the day. If you do take it at night, just be aware it could potentially cause insomnia for some.

What should I avoid when taking fexofenadine?

Avoid consuming grapefruit juice or orange juice within a few hours of your fexofenadine dose, as the juices can impact how well the medication absorbs. Also, skip antacids with aluminium or magnesium, as they can decrease fexofenadine absorption. Otherwise, there are very few food/beverage restrictions.


NHS (2021). Fexofenadine -

René Maximiliano Gómez, MD, PhD, Pablo Moreno, MD, Enrico Compalati, MD, PhD, Giorgio Walter Canonica, MD, PhD, and Ignacio Javier Ansotegui Zubeldia, MD, PhD (2023). Update meta-analysis on the efficacy and safety issues of fexofenadine -

Fexofenadine 180mg Tablets: Patient Information Leaflet -

Cetirizine 10mg Tablets: Patient Information Leaflet -

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