Zyrtec side effects and how to avoid them

Common Zyrtec side effects | Serious side effects | Side effects timeline | Interactions | Safety measures | How to avoid side effects | How to treat side effects

Zyrtec is an over-the-counter (OTC) antihistamine that temporarily relieves hay fever and allergy symptoms, such as runny nose, sneezing, and itchy, watery eyes. Zyrtec comes in a variety of dosage forms, including tablets, chewable tablets, liquid gel capsules, orally disintegrating tablets, and syrup. Two brand-name products, Zyrtec Allergy and Children’s Zyrtec Allergy, contain the active ingredient cetirizine. This is a second-generation antihistamine that doesn’t cause serious drowsiness and impairment in the same way as first-generation antihistamines, such as Benadryl (diphenhydramine). The manufacturer also sells a combination drug, Zyrtec-D Allergy + Sinus, which contains both cetirizine and the decongestant pseudoephedrine. Cetirizine works by blocking histamines, which are chemicals produced by the body in response to allergens. Histamines signal the immune system and promote inflammation, causing most of the symptoms of an allergic reaction. 

Common side effects of Zyrtec

The most commonly experienced side effects of Zyrtec are headache and drowsiness. The drowsiness is dose-related, and children are more likely to experience this side effect than adults. 

Other common side effects of Zyrtec are:

• Headache
• Sore throat
• Abdominal pain
• Tiredness
• Dry mouth
• Cough
• Nosebleeds
• Diarrhea
• Nausea
• Vomiting
• Pink eye (conjunctivitis)
• Allergic reactions

Symptoms of an allergic reaction to Zyrtec include:

• Runny nose (allergic rhinitis)
• Hives (urticaria)
• Trouble breathing
• Wheezing
• Swelling of the face, mouth, or lips
• Itchy, watery eyes
• Red eyes

Serious side effects of Zyrtec

When taken as directed, Zyrtec and OTC cetirizine only rarely cause serious side effects. The most likely serious side effect is a severe and life-threatening allergic reaction called anaphylaxis. The symptoms of anaphylaxis include:

• Airway closure
• Low blood pressure
• Lightheadedness
• Dizziness
• Weak pulse
• Fast heartbeat
• Nausea
• Vomiting
• Fainting or passing out

Other severe side effects of Zyrtec may include an elevation in liver enzymes. This is often an indication that the drug is affecting liver function. After cetirizine is discontinued, liver enzymes should return to normal.

How soon do Zyrtec side effects start?

The most commonly experienced side effects of Zyrtec start early in treatment. These include somnolence, headache, dry mouth, nausea, vomiting, and diarrhea. An allergic reaction, including anaphylaxis, can start very rapidly after taking a dose. Other side effects, such as cough and sore throat, may be delayed. 

How long do Zyrtec side effects last?

In some people, Zyrtec side effects may improve over time as the body gets used to the drug. Most Zyrtec side effects will fade when the drug is discontinued. The half-life of cetirizine is eight hours in healthy people, but it could be longer in people with liver dysfunction. A half-life is the amount of time it takes the body to eliminate half of a dose. With a half-life of eight hours, the effects of Zyrtec should last about a day and a half. In people with liver disease, Zyrtec effects can last for two to three days after the last dose. 

What are the long-term side effects of Zyrtec?

There are no Zyrtec side effects due to long-term use. However, people who take Zyrtec or any other cetirizine product continuously for months or years may experience withdrawal symptoms when the drug is stopped. Called “Zyrtec withdrawal,” this syndrome is very rare. The most commonly reported symptom of Zyrtec withdrawal is intense itching, which some people report is unbearably severe. Other possible withdrawal symptoms include hives, headaches, and vivid dreams. 

Zyrtec interactions

As with all antihistamines, Zyrtec has a few drug interactions that may increase the risk or severity of side effects. Because Zyrtec causes sleepiness, the most concerning drug interactions involve drugs that also cause sedation, such as:

• Other antihistamines
• Tranquilizers
• Opioids
• Benzodiazepines
• Gabapentin
• General anesthetics
• Alcohol
• Cannabis

Safety measures while using Zyrtec

What are the FDA warnings about Zyrtec?

The Food and Drug Administration (FDA) has not issued warnings about the use of Zyrtec. The manufacturer once recalled several hundred thousand blister packs because of a possible impurity, but it was not mandated by the FDA.

Who should never take Zyrtec?

Anyone who has had an allergic reaction to Zyrtec, cetirizine, or hydroxyzine should not take Zyrtec.

Who should use caution with Zyrtec?

As an OTC medication, Zyrtec is considered to be safe to take without the supervision of a healthcare professional. However, it can cause problems in certain groups of people and those with certain medical conditions, such as the following:

• Women who are pregnant: Although considered safe to take when pregnant, the manufacturer advises that women get medical advice from a healthcare professional before using Zyrtec. 

• Women who are breastfeeding: The manufacturer does not recommend Zyrtec use by women who are breastfeeding.

• People with liver disease or kidney disease: People with liver dysfunction or kidney impairment should talk to their healthcare provider before taking Zyrtec. Liver impairment makes it harder for the body to eliminate the drug, so people with liver problems are exposed to higher levels of Zyrtec for a longer period of time than healthy adults are. Doses may need to be reduced in these patients in order for Zyrtec to be taken safely.

• Children younger than two years of age: Talk to a pediatrician or other healthcare provider before giving Zyrtec to a child younger than two years of age.

• Adults older than 65 years of age: Although Zyrtec is an antihistamine, it also has effects similar to anticholinergic drugs. This is why it causes side effects like dry mouth. For this reason, some OTC cetirizine product labels recommend that seniors get medical advice from a doctor before taking it, but Zyrtec does not include this recommendation on its packaging. The Prescriber’s Digital Reference recommends a dose of 5 milligrams per day in adults ages 77 years and older.

Does Zyrtec cause drug abuse or dependency?

The FDA does not consider Zyrtec to be an addictive drug or one prone to drug abuse. Although cetirizine does not cause a physical dependency, there are rare cases where people who have taken cetirizine chronically for months or years experience withdrawal symptoms, primarily marked by moderate to severe itching.

Can you overdose on Zyrtec?

Cetirizine should be taken as instructed. The most common symptom of a cetirizine overdose is drowsiness. Most case reports involve children who have gotten unsupervised access to cetirizine around the house. As with all OTC drugs, keep Zyrtec out of the reach of children. If a Zyrtec overdose is suspected, contact Poison Control at 800-222-1222.

How to avoid Zyrtec side effects

Although Zyrtec is considered safe enough to use without a prescription, some people will have side effects. However, these side effects can be prevented or minimized by taking a few precautions:

1. Take Zyrtec as instructed.

Read the package label or drug insert before taking Zyrtec. Read the warnings and follow the dosing instructions. If administering this drug to children, carefully read the dosing instructions to make sure the right dose is being given. You can take a missed dose the day it’s scheduled, but you should never take two doses in a single day.

2. Don’t take too much.

Taking more than the recommended dose will probably not help allergy symptoms, but it will certainly raise the risk of side effects. If the medicine isn’t working, switch to a different antihistamine or talk to a healthcare provider.

3. Try to avoid using Zyrtec over a long period of time.

If antihistamines are required daily for months or longer, talk to your healthcare provider about alternative treatment options. Long-term use of Zyrtec can cause withdrawal symptoms in some people. 

4. Get medical advice from a healthcare professional. 

Zyrtec is more likely to cause side effects in some people than it is in others. Young children, seniors, and people with liver or kidney disease may experience more side effects. People taking certain types of drugs that may interact with Zyrtec can also be at an increased risk of experiencing side effects. If there’s a question, ask a primary care provider about how to take Zyrtec.

5. Avoid alcohol and cannabis.

Both alcohol and cannabis products can significantly increase the risk and severity of drowsiness and impairment in someone taking Zyrtec.

6. Be careful when driving. 

Drowsiness and impairment may make driving, operating machinery, or engaging in risky activities more hazardous. 

How to treat side effects of Zyrtec

Zyrtec side effects are relatively minimal, but they may be an issue if Zyrtec needs to be taken for a while. 

Drowsiness

There’s little to do about drowsiness or dizziness caused by Zyrtec other than wait it out. Plan to take the dose at a time when drowsiness will not interfere with daily activities. If Zyrtec is making you drowsy or tired, take the daily dose at night.

Headache

Headaches caused by Zyrtec are comparatively mild and can be treated with OTC pain relievers, like ibuprofen or acetaminophen.

Nausea, vomiting, and stomach pain

If nausea, vomiting, or abdominal pain seem to be caused by Zyrtec, try taking the dose with food to see if it can improve these symptoms. If that doesn’t help, talk to a healthcare professional. 

Dry mouth

If dry mouth is a problem, try to fix it by drinking fluids, chewing gum, or sucking on hard candies.

Allergic reactions

If you experience even a mild allergic reaction to Zyrtec, immediately stop taking the drug and get medical help.

Zyrtec withdrawal

If you discontinue taking Zyrtec after long-term use and get itchy two to three days later, call a healthcare professional. There may be temptation to restart Zyrtec if the itching is unbearable, but healthcare professionals can treat it with a short course of corticosteroids.

Bottom line: Is Zyrtec safe?

As an OTC medicine, Zyrtec is safe to take without the supervision of a medical professional. Most people do not experience side effects. When they do, those adverse effects are comparatively mild. The only notable serious side effect is severe allergic reactions, but this is also possible with other store-bought medicines and supplements. Young children, seniors, or people with liver or kidney problems should take Zyrtec with caution. A doctor or other healthcare provider can provide safety guidance for these patients.