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Zyrtec-D side effects and how to avoid them

Zyrtec-D has a few more side effects than regular Zyrtec because of the addition of pseudoephedrine
Gerardo Sison medical writer headshot
By | Jan. 10, 2025
A prescription bottle with an exclamation mark on it: Zyrtec-D side effects and how to avoid them

Key takeaways

  • Zyrtec-D combines cetirizine and pseudoephedrine to relieve allergy symptoms but may cause side effects that regular Zyrtec doesn’t.

  • Common side effects include drowsiness, insomnia, dry mouth, nausea, headache, sore throat, and fatigue.

  • Serious side effects can involve irregular heartbeat, high blood pressure, seizures, and allergic reactions.

  • Long-term use may increase risks of dementia and cardiovascular problems; consult a healthcare provider if you have any concerns.

In this article:

Seasonal allergies can be bothersome, leading to symptoms such as an itchy nose, sneezing, runny nose, and itchy eyes. For many people, a dose of Zyrtec (cetirizine HCL) can work wonders for relieving annoying allergy symptoms. It’s a brand-name over-the-counter (OTC) drug that contains cetirizine and works by blocking the effects of histamine, a substance that can trigger allergic reactions and inflammation. 

While Zyrtec can be effective for various allergy symptoms, people experiencing a stuffy nose might benefit more from Zyrtec-D (cetirizine pseudoephedrine Er). This brand-name version of Zyrtec combines an antihistamine with the decongestant pseudoephedrine, which helps shrink blood vessels in the nose and sinuses to reduce congestion. Still, Zyrtec-D may cause side effects, some of which can be more severe than those with regular Zyrtec. Read on to learn more about the potential side effects of Zyrtec-D. 

Common side effects of Zyrtec-D

Drowsiness is one of the most common side effects of cetirizine. While it typically causes less drowsiness than first-generation antihistamines like Benadryl (diphenhydramine), some people may still experience this effect. On the other hand, pseudoephedrine, the second active ingredient in Zyrtec-D, is more commonly linked to trouble sleeping or insomnia.

The most common side effects associated with Zyrtec-D include: 

  • Drowsiness
  • Insomnia
  • Dry mouth 
  • Nausea 
  • Headache 
  • Sore throat
  • Fatigue 

Serious side effects of Zyrtec-D

Most side effects of Zyrtec-D are mild and temporary. However, this medication also comes with a risk of serious side effects. If any side effects persist or worsen, it’s recommended to consult a healthcare professional.

Potentially serious side effects of Zyrtec-D may include:

Zyrtec-D may also cause severe allergic reactions, with symptoms like skin rash, trouble breathing, or swelling of the face or throat. If you experience serious side effects, seek medical attention immediately.

Zyrtec vs. Zyrtec-D side effects

Zyrtec-D has more side effects than Zyrtec because it has two active ingredients instead of one. While they both share the side effects of the active ingredient cetirizine, Zyrtec-D also has pseudoephedrine side effects to contend with. Understanding the side effects of Zyrtec-D can be challenging because pseudoephedrine and cetirizine have contrasting effects. Cetirizine can cause central nervous system (CNS) depressant effects such as drowsiness and dizziness, while pseudoephedrine can cause stimulant effects like increased heart rate and insomnia. 

When you take Zyrtec-D, you might experience mixed effects—some people may feel tired, while others may feel restless. This mix can make it hard to know how the medication will affect you, so it’s important to pay attention to how your body responds. Side effects can also depend on how much of the medication you take, with larger doses often causing more and stronger side effects.

How soon do Zyrtec-D side effects start?

The side effects of Zyrtec-D can appear as soon as the medication starts working. For most people, Zyrtec starts working within an hour after taking it. Common side effects like drowsiness, dizziness, or dry mouth can appear during this time. 

Other side effects, like nausea or trouble sleeping, may take a bit longer to show up. Since each person’s body is different, the onset time can differ. In some cases, side effects might not show up until a person has taken the medication for a couple of days.

How long do Zyrtec-D side effects last?

The side effects of Zyrtec-D can vary in how long they last. Most side effects are temporary and generally go away as the body adjusts to the medication. Side effects can develop as long as the medication is used but may become more bearable over time. If side effects last several days or worsen, consult a healthcare provider for medical advice.

What are the long-term side effects of Zyrtec-D?

Using antihistamines like cetirizine for a long time might increase the risk of developing dementia, especially if taken in large amounts. Research shows that both first-generation and second-generation antihistamines can carry this risk, with higher chances of dementia as the dosage increases. One study found that the risk becomes even greater for those who take more than 120 doses over time.

Similarly, long-term use of stimulants like pseudoephedrine can also come with serious health risks. These medications may increase the chances of having a stroke or a heart attack. This happens because stimulants can affect the heart and blood vessels, making them work harder than normal. Over time, this extra strain on the cardiovascular system can lead to dangerous health problems, especially in those with heart disease or other heart problems.

Zyrtec-D interactions

Zyrtec-D can interact with several other medications, which may lead to increased side effects or reduce the effectiveness of either drug. It may be helpful to be aware of these potential drug interactions and consult a healthcare professional before combining Zyrtec-D with other medications.

Potential medications that Zyrtec-D can interact with include the following.

Other CNS depressants

Combining Zyrtec-D with other CNS depressants can increase sedation. This can result in increased drowsiness, dizziness, and impaired coordination. Examples of CNS depressants include benzodiazepines, barbiturates, opioids, muscle relaxants, and sleep medications. 

Monoamine oxidase inhibitors (MAOIs)

Using pseudoephedrine alongside MAOIs can increase the risk of severely high blood pressure. Examples of MAOIs include Nardil (phenelzine), Parnate (tranylcypromine), and Emsam (selegiline). 

Tricyclic antidepressants (TCAs)

The combination of Zyrtec-D with tricyclic antidepressants can increase the risk of side effects such as abnormal heartbeat and high blood pressure. Examples of TCAs include Elavil (amitriptyline), Pamelor (nortriptyline), and Silenor (doxepin)

Blood pressure medications

Pseudoephedrine can raise blood pressure and counteract the effects of antihypertensive medications. Caution is recommended when combining these drugs. Examples of blood pressure medications include Zestril (lisinopril), Norvasc (amlodipine), and Cozaar (losartan).

It’s always important to inform a healthcare provider about all medications being taken to avoid potential interactions. Make sure to mention other prescription drugs, OTC medicines, and herbal supplements. 

Zyrtec-D and alcohol

Mixing Zyrtec-D with alcohol might increase drowsiness and slow thinking or reactions. Both cetirizine hydrochloride and alcohol have sedative properties, which can lead to amplified sedative effects when taken together. Given these interactions, activities like driving or using machinery can become dangerous. It’s usually recommended to avoid drinking alcohol or at least limit it while taking Zyrtec-D.

Safety measures while using Zyrtec-D

Zyrtec-D has important warnings and precautions to think about before taking it. The two main ingredients, cetirizine and pseudoephedrine, have their own risks, so it’s important to understand those before taking the medication.

Those with an allergy to Zyrtec-D

Zyrtec-D should be avoided in people who have a hypersensitivity or allergy to cetirizine, pseudoephedrine, or any ingredients in the medication. Taking this medication could cause severe allergic reactions in these individuals. It’s also important to avoid Zyrtec-D if you have an allergy to hydroxyzine, as cetirizine is derived from hydroxyzine.

People with liver problems

For people with liver problems, the dosage of cetirizine should be reduced. This is because the liver helps break down the medication, and the body can’t process the drug effectively when it’s not working well. A lower dose helps prevent buildup in the body, which can lead to stronger side effects.

People with kidney problems

The dosage of Zyrtec-D should also be reduced for people with kidney issues (specifically those whose kidneys filter waste at a slower rate). The kidneys are responsible for removing waste and excess medication from the body. Medications can accumulate and cause unwanted side effects if the kidneys aren’t working well.

Older adults

Studies on cetirizine have not included many patients ages 65 and older. While safety tests show no major differences in side effects compared to younger adults, older individuals may be more sensitive to the effects of antihistamines. Therefore, older adults may need to consider taking lower doses.

Other medical conditions

Tell a healthcare provider about any medical conditions before taking Zyrtec-D. You may want to mention whether you have a history of kidney disease, liver disease, glaucoma, enlarged prostate, thyroid problems, and cardiovascular problems. 

Precautions during pregnancy or breastfeeding

Cetirizine is considered to be safe during pregnancy, according to animal studies. On the other hand, pseudoephedrine is not typically recommended during pregnancy, especially within the first three months of pregnancy. 

When it comes to breastfeeding, taking small doses of cetirizine is unlikely to cause harm if the benefits outweigh the risks. However, if a mother uses larger doses for a long time, it might reduce her breast milk supply or cause drowsiness and other side effects in the baby. It’s important for breastfeeding mothers to talk to a healthcare provider before using antihistamines to make sure they are safe for both them and their babies.

How to avoid Zyrtec-D side effects

By following certain guidelines, you can have a better chance of reducing the side effects of Zyrtec-D. Some side effects may be unavoidable, but you can take steps to make them less severe.

Take the correct dose

Always stick to the recommended amount of Zyrtec-D as shown on the package or given by a healthcare professional. Taking more than what’s recommended can lead to side effects like feeling sleepy or having an increased heart rate. If you’re unsure how much to take, ask your healthcare provider or pharmacist for help.

Take the tablet whole 

Zyrtec-D is an extended-release tablet that slowly releases its ingredients into your body over time. It’s important to swallow the tablet whole without breaking, splitting, or chewing it. Breaking the tablet can cause the medication to be rapidly absorbed, which may cause more side effects.

Watch your timing of medication

What time of day you take Zyrtec-D may be important. It’s a good idea to take it at the same time every day to keep steady levels in your body. Some people find it helpful to take it in the morning if they experience insomnia or in the evening if they experience tiredness.

Avoid medications that interact

Be careful with other medications you are taking along with Zyrtec-D, as some can cause problems. Always tell your healthcare provider about any other drugs or supplements you are using to avoid interactions that might make side effects worse.

Take it with food

Taking Zyrtec-D with food may help reduce gastrointestinal side effects like nausea or upset stomach. A light meal may help alleviate stomach pain and doesn’t negatively affect how the medication is absorbed.

Avoid alcohol

It’s best to stay away from alcohol while taking Zyrtec-D. Alcohol can worsen the drowsiness and dizziness from Zyrtec-D, making it harder to think clearly and maintain balance.

Skipping missed doses 

If you miss a dose of Zyrtec-D, take it as soon as you remember. However, if it’s almost time for your next dose, skip the missed dose and continue with your regular schedule. Do not take two doses at once to make up for a missed dose, as this can increase the risk of side effects.

Limit long-term use of high doses

Try not to use high doses of Zyrtec-D for a long time if you can avoid it. Using it for extended periods may lead to more side effects and increased tolerance. Withdrawal after long-term use may cause increased hives, headaches, and other symptoms.

How to treat side effects of Zyrtec-D

Side effects of Zyrtec-D are generally mild and don’t require professional medical attention. You can often manage mild side effects with simple home remedies. 

For example, drinking plenty of water may help manage a dry mouth. If you experience dizziness, try sitting or lying down until it passes. Rising slowly from a sitting or lying position may also help prevent dizziness.

Some side effects may require more attention. You should seek medical attention for the following side effects:

  • Severe drowsiness
  • Severe rash, itching, or swelling
  • Difficulty breathing or swelling
  • Fast, irregular heartbeat
  • Seizures

You should also seek medical help if side effects persist or worsen, especially if they affect your ability to work or carry out other daily activities. A healthcare provider can provide supportive care and medical advice to manage serious side effects.

Bottom line: Is Zyrtec-D safe?

Zyrtec-D can be a good choice for managing seasonal allergy symptoms, especially for people who experience nasal congestion. However, it can cause side effects, which can range from mild problems like drowsiness and dry mouth to more serious risks like irregular heartbeat or high blood pressure. 

You can reduce potential side effects by taking the recommended dosage, avoiding alcohol, and being aware of any other medications you may be taking. If you have severe or ongoing symptoms or if you have any health conditions, it’s always best to talk to a healthcare provider.

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