7 Zyrtec Side Effects You Should Know About

GoodRx Health

Zyrtec (cetirizine) is an antihistamine that treats allergies. It's available both over the counter (OTC) and with a prescription, and it's generally well-tolerated. But as with any medication, there are some potential side effects to know about.

Here, we'll review common and rare Zyrtec side effects you should know about and how to manage them if they occur.

Zyrtec side effects at a glance

Below are the mild and serious Zyrtec side effects reported in clinical studies. Keep in mind that everyone responds differently to medication. So it's best to reach out to a healthcare professional if you experience any concerning side effects while taking Zyrtec, even if they aren't listed here.

Mild Zyrtec side effects include:

• Drowsiness

• Fatigue

• Sore throat

• Stomach pain

• Dizziness

• Dry mouth

• Headache

• Diarrhea

• Nose bleeds

• Nausea and vomiting

• Cough

Rare but serious Zyrtec side effects include:

• Trouble peeing

• Blurred vision

• Hearing problems

• Mood or behavior changes

• Movement disorders

• Seizure

• Very low blood pressure

• Liver problems

Below, we'll go into more detail about seven Zyrtec side effects and how to manage them.

1. Drowsiness

Feeling drowsy is a common Zyrtec side effect. It's typically not as severe as the drowsiness caused by first-generation antihistamines, such as diphenhydramine (Benadryl). But it can be bothersome for some people. It's best to avoid driving or other activities that require alertness until you know how Zyrtec affects you.

Drowsiness seems to be a dose-related side effect. Lowering your Zyrtec dosage may help you manage this side effect. Taking Zyrtec in the evening is another option if daytime drowsiness is bothersome for you.

But if drowsiness persists or it's interfering with your ability to perform daily tasks, talk to your pharmacist or prescriber about a non-drowsy allergy treatment. Allegra (fexofenadine) and Claritin (loratadine) are both effective OTC options.

2. Dry mouth

Dry mouth can be a side effect of antihistamines. It's more common with first-generation antihistamines, but it can happen with newer antihistamines, such as Zyrtec, too. Dry mouth seems to increase as the Zyrtec dosage goes up. So lowering your dose may help resolve it.

You can help counteract dry mouth by sipping on water throughout the day, chewing sugar-free gum, or using a saliva substitute spray. If you're taking Zyrtec long term and it's causing dry mouth, it's also a good idea to stay on top of your dental appointments. Over time, dry mouth can lead to tooth decay without proper dental care.

3. Sore throat

Sore throat is another possible Zyrtec side effect. It may be related to dry mouth, since producing less saliva can also leave your throat feeling dry and make it more painful to swallow. But keep in mind that allergies can also cause a sore throat due to post-nasal drip.

You can soothe a sore throat with a salt water gargle. Staying hydrated can also help. If needed, an OTC pain medication, such as Advil (ibuprofen) or Chloraseptic spray, may also help. Just make sure your healthcare team OKs it.

If you have other allergy symptoms along with a sore throat, it could be a sign that Zyrtec isn't working well for you. If you have a fever or swollen lymph nodes in your neck along with a sore throat, it's best to seek medical care. You could have an infection that requires treatment.

4. Nausea

Nausea isn't common with Zyrtec, but it happens for some people taking it. Stomach pain has also been reported. You can take Zyrtec with or without food. But if it's making you nauseous, taking it with food may help. Just be sure to avoid spicy or greasy foods, as they can worsen nausea.

If your nausea worsens or doesn't improve, talk to your pharmacist or prescriber about a different treatment option for your allergy symptoms.

5. Diarrhea

Diarrhea is another possible Zyrtec side effect. It seems to be more common in children taking Zyrtec than in adults.

Diarrhea may improve over time as your body adjusts to the medication. Be sure to drink fluids to avoid dehydration if you have diarrhea.

If needed, an OTC medication, such as Imodium A-D (loperamide) or Pepto-Bismol (bismuth subsalicylate), may help manage your diarrhea. But if it continues for more than a few days, or becomes severe, talk with a healthcare professional. They can make sure there isn't a more serious cause of your symptoms.

6. Mood changes

While less common, Zyrtec can sometimes cause mood changes, such as agitation, anxiety, or mood swings. Hallucinations and suicidal thoughts can also happen in rare cases.

If you notice a change in your behavior (or your child's) after taking Zyrtec, it's best to stop taking it and seek medical care. If thoughts of self-harm are involved, emergency care is recommended.

If you or someone you know is having thoughts of suicide, you're not alone, and help is available. Call the National Suicide Prevention Lifeline at 988, or text "HOME" to 741-741 to reach the Crisis Text Line.

7. Liver problems

In rare instances, some people have reported liver problems while taking Zyrtec. This isn't common, and in most cases it will resolve once you stop taking Zyrtec.

Signs and symptoms of liver damage include:

• Stomach pain

• Yellow-colored skin or eyes (jaundice)

• Dark-colored urine

• Swollen stomach

If these symptoms appear while you're taking Zyrtec, seek medical care as soon as possible.

Does Zyrtec cause weight gain?

It's possible. Histamine plays a role in regulating appetite and body weight. Zyrtec blocks histamine to control allergy symptoms. But this may have a negative effect on the body's ability to regulate weight, leading to weight gain over time. Weight gain from Zyrtec and other second-generation antihistamines doesn't seem to be an issue with short-term use. But if you're taking Zyrtec long term, talk to a healthcare professional about any concerns about its effect on your weight.

Does Zyrtec raise your blood pressure?

Both increased and decreased blood pressure were reported in clinical studies of Zyrtec. But these aren't common Zyrtec side effects. Zyrtec is considered a safe medication to take if you have high blood pressure (hypertension). Just be sure to avoid Zyrtec-D, as it contains a decongestant (pseudoephedrine) along with Zyrtec. Zyrtec-D can raise your blood pressure and isn't recommended if you have hypertension.

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