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What Are Zyrtec's Inactive Ingredients?

Understanding What's In Zyrtec

Dr. Lyssa Logue Profile Photo

Written by Dr. Lyssa Logue on October 7, 2021

Medically reviewed by Camille Freking, MS Pharmacology

Zyrtec is a popular over the counter medication for the treatment of seasonal allergies and perennial allergies.

Unlike allergy medications like Benadryl, which are designed to be used on a short term basis for the management of acute symptoms, Zyrtec is intended for use for up to six months. As a result, the medication can be used to control allergy symptoms that occur throughout a significant part of the year.

If you’re considering using Zyrtec to help control your allergy symptoms, you might be wondering “what are Zyrtec’s inactive ingredients?”

What is the difference between active and inactive ingredients?

The first thing to understand about medications is that all drugs contain two types of ingredients, known as active ingredients and inactive ingredients. The definitions for both types of ingredients were developed by the U.S. Food and Drug Administration (FDA) under 21 Code of Federal Regulations (CFR) 210.3,Current Good Manufacturing Practice in Manufacturing, Processing, Packing or Holding of Drugs.

Under 21 CFR 210.3Part (b)(7), an active ingredient is defined as any component of a drug product that is intended to furnish pharmacological activity or other direct effect in the diagnosis, cure, mitigation, treatment, or prevention of disease, or to affect the structure or any function of the body of humans or animals.

In simpler terms, active ingredients are the components of a medication that treat a patient’s symptoms and provide relief. If you have a sore throat, the active ingredient would be the ingredient that reduces the pain associated with your condition.

Inactive ingredients, which make up approximately 75 percent of most medications, are defined by 21 CFR 210.3(b)(8) as any component of a drug product other than the active ingredient. Inactive ingredients play an important role in influencing how a medication looks, tastes, and feels.

Inactive ingredients perform many different functions in medication, including:

  • Binding the ingredients together to give the medicine a cohesive shape
  • Preserving the medication by preventing the growth of bacteria and fungi
  • Helping the body to absorb the drug more easily by combining with an easily digestible substance like a fatty acid
  • Masking the bitter taste of some medications to make them easier to swallow
  • Preventing a medication from being dissolved

What are Zyrtec’s active ingredients?

Zyrtec is produced in six different formulas: Zyrtec Tablets, Zyrtec Liquid Gels, Zyrtec Dissolve Tabs, Zyrtec-D, Children’s Zyrtec Dissolve Tabs, and Children’s Zyrtec Syrup. Of these formulas, Zyrtec Tablets and Zyrtec-D are produced as tablets, while Zyrtec Liquid Gels are produced as liquid-free capsules.

Because the Zyrtec Tablets are the formula with which most people are familiar, this article describes the active and inactive ingredients in that particular formula.

Zyrtec tablets contain 10 mg of cetirizine HCl, the only active ingredient, in each tablet.

Adults and children ages six and older are directed to take one tablet per day to control allergy symptoms; however, some patients with less severe symptoms may be able to control their allergies with one 5 mg dose.

Cetirizine HCl, the active ingredient in Zyrtec, is an over the counter antihistamine that controls mild to moderate allergy symptoms by blocking the effects of a substance called histamine in the body.

The body produces histamine as part of an immune response targeting a given allergen, and the release of histamine causes allergy symptoms like sneezing, itchy or watery eyes, runny nose, itchy throat, and itchy nose. Allergy symptoms can occur on a seasonal basis in response to plant or tree pollen or mold, or it can occur on a perennial basis in response to allergens like pet dander and dust mites. It is possible for people to experience both seasonal and perennial allergies.

What are Zyrtec’s inactive ingredients?

Zyrtec tablets contain the following inactive ingredients: colloidal silicon dioxide, croscarmellose sodium, hypromellose, lactose monohydrate, magnesium stearate, microcrystalline cellulose, polyethylene glycol, and titanium dioxide.

Colloidal silicon dioxide, also known as sand or quartz, is a naturally occurring mineral that is found throughout the earth’s crust. We naturally consume silicon dioxide and other silicates as part of our daily diet because they are found in water, animals, and plants. Colloidal silicon dioxide is commonly used in medication as an anti-caking agent, disintegrant, adsorbent, or glidant that allows powder to flow freely when a tablet is processed by the body.

Croscarmellose sodium is a type of salt that is used as a disintegrant in some types of medication, including tablets like Zyrtec. Croscarmellose sodium appears as a chain of cellulose, making it different from most types of cellulose, which appear as short, individual fibers. Disintegrants like croscarmellose sodium are included in medications because they help the tablets to rapidly disintegrate in the stomach, improving the speed at which the medication is absorbed by the body.

Hypromellose is considered the most commonly used cellulose. This ingredient is included in tablets like Zyrtec because it helps to control the release of the active ingredient, cetirizine HCl, by extending the length of time that it takes for the active ingredient to be released by the body. Medications need to be released quickly enough to provide relief, but they also need to last long enough to maintain a therapeutic effect and prevent the patient from needing to consume more and more of the drug to feel better.

Lactose, an inactive ingredient derived from dairy products, is a type of milk sugar. Lactose contains one molecule of galactose and one molecule of glucose and is highly compressible, which makes it useful in helping to form tablets and maintain their shape. Lactose may be listed on medication labels as lactose hydrous, lactose anhydrous, lactose monohydrate, or lactose spray-dried.

Magnesium stearate is a common inactive ingredient that is often included in tablets like Zyrtec. Magnesium stearate is used to prevent the multitude of ingredients in a capsule or tablet from sticking to each other and from sticking to the equipment that is used to produce the medication. Additionally, this inactive ingredient is used to help improve the consistency of medication capsules and delay the rate at which the active ingredients are broken down and absorbed.

Microcrystalline cellulose is a type of cellulose that is classified as an excipient and is used to make tablets like Zyrtec hard but easily dissolvable.

Polyethylene glycol can be used as an inactive ingredient for a number of different purposes, including acting as a solvent, plasticizer, capsule, surfactant, and tablet lubricant. As an inactive ingredient in Zyrtec, polyethylene glycol makes tablets easier to swallow.

Titanium dioxide is a naturally occurring mineral that is commonly used in medications as a pigment for the coatings on tablets like Zyrtec.

Are inactive ingredients associated with any risks?

Over the counter medications and prescription drugs all contain inactive ingredients that are included in order to improve qualities like the appearance, taste, color, absorption rate, and other qualities of the drug.

Unlike active ingredients, which provide a therapeutic benefit and improve your symptoms, inactive ingredients do not have a therapeutic benefit but make up the majority of most medications.

While the FDA categorizes inactive ingredients as generally recognized as safe, these ingredients can cause adverse effects in people with certain allergies or sensitivities. Two of the most common risks associated with inactive ingredients in general include allergic reactions and digestive distress due to intolerances.

Inactive ingredients can cause allergic reactions that range in severity from mild to severe. A total of 38 different inactive ingredients have been identified as potential allergens that are commonly included in medications, and approximately93 percent of medications included as part of one study contained at least one potential allergen.

For example, Zyrtec contains lactose, which is derived from dairy products and can cause an allergic reaction in some people. The effects of allergic reactions can range from skin irritation, such as itching or hives, to anaphylaxis, which can cause trouble breathing.

Inactive ingredients can also cause digestive distress in some people, resulting in symptoms like gas, bloating, nausea, and diarrhea. These symptoms are most commonly associated with ingredients that contain sugars that are difficult for the body to digest, such as lactose.

The more medications you take, the more inactive ingredients you are exposed to. As a result, although you can experience adverse effects from any inactive ingredient in any amount, you are more likely to experience adverse reactions as you take more medications.


Zyrtec tablets contain 10 mg of cetirizine HCl per tablet as the active ingredient. In addition to cetirizine HCl, Zyrtec tablets contain the following inactive ingredients: colloidal silicon dioxide, croscarmellose sodium, hypromellose, lactose monohydrate, magnesium stearate, microcrystalline cellulose, polyethylene glycol, and titanium dioxide.Inactive ingredients are found in all types of prescription drugs and over the counter medications, and while they are generally recognized as safe, these ingredients can cause allergic reactions or digestive distress in some people.