Ross is a writer for Verywell with years of experience practicing pharmacy in various settings. She is also a board-certified clinical pharmacist and the founder of Off Script Consults.

Femi Aremu, PharmD, is a professional pharmacist with experience in clinical and community pharmacy. He currently practices in Chicago, Illinois.

Clarinex (desloratadine ) is a prescription treatment option to relieve allergy symptoms, itchiness, and hives. It's a second-generation histamine (H1) antagonist, which works by blocking histamine release in the body. Histamine is a chemical responsible for causing allergy symptoms.

Clarinex is available as a regular tablet, an easily dissolvable tablet, and as an oral syrup.

Administration Route: Oral (by mouth)

Therapeutic Classification: Second-generation histamine (H1) antagonist

Dosage Form: Tablets, oral syrup

Clarinex is used to relieve allergy symptoms. It may also help with itchiness and hives (skin rash).

In the United States (U.S.), millions of people have allergies every year. Allergy symptoms may include sneezing, runny nose, itchiness, and rash. Allergies happen when your immune system (the body's defense system) overreacts to certain allergens (triggers). Examples of some triggers are pollen, dust mites, and pet dander.

Some people, however, experience itchiness and rashes without a trigger. This medical condition is called chronic (long-term) idiopathic urticaria (hives). Idiopathic is a term that means of unknown cause.

Fortunately, in addition to relieving allergy symptoms, the Food and Drug Administration (FDA) also approved Clarinex to treat these types of hives.

Clarinex is typically taken by mouth once daily with or without food.

Clarinex has two different types of tablets: a regular tablet and an orally disintegrating tablet (ODT). The ODT is an easily dissolvable tablet. It's also called a RediTab. Once placed on the tongue, it quickly breaks apart and dissolves without any need for water. Just wait for the tablet to dissolve before swallowing.

Clarinex is a non-controlled medication. Therefore, your healthcare provider can authorize refills for up to one year from the original written date on the prescription.

When you bring Clarinex home from the pharmacy, the medication has a safe storage range between 59 degrees to 86 degrees Fahrenheit (F). As a result, room temperature will typically be an acceptable environment. Clarinex, however, is sensitive to heat. Therefore, avoid temperatures above 86 degrees F. Also, protect this medication from moisture.

If travel with Clarinex, become aware of your final destination's regulations. In general, make a copy of your Clarinex prescription and keep the medication in its original container from the pharmacy, with your name on it.

Clarinex has some off-label uses.

In fact, experts recommend Clarinex as an effective treatment option for acute (new-onset) hives. A 2016 study also suggests that Clarinex might be a potential preventative option for people with hives from nonsteroidal anti-inflammatory drugs (NSAIDs)—like Advil (ibuprofen).

You might start to notice Clarinex effects within one hour.

This is not a complete list of side effects and others may occur. A healthcare provider can advise you on side effects. If you experience other effects, contact your pharmacist or a healthcare provider. You may report side effects to the Food and Drug Administration (FDA) at fda.gov/medwatch or 800-FDA-1088.

Common side effects with Clarinex include:

Get medical help right away if you experience a severe allergic reaction to Clarinex. Symptoms of a severe allergic reaction may include:

Second-generation histamine (H1) antagonists—like Clarinex—have good long-term safety profiles. In fact, this class of antihistamines has little to no side effects with long-term use.

In children, there are also no differences in the safety profiles between this antihistamine class and placebo (a substance with no medicine in it).

Clarinex may cause other side effects. Call your healthcare provider if you have any unusual problems while taking this medication.

If you experience a serious side effect, you or your provider may send a report to the FDA's MedWatch Adverse Event Reporting Program or by phone (800-332-1088).

The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

For patients using the oral disintegrating tablet form of this medicine:

For patients using the syrup form of this medicine: Use a calibrated measuring dropper or syringe to measure the direct dose for your child based on your doctor's instructions. Do not use a regular teaspoon. If you are unsure about how much of the syrup to give to your child, ask your doctor or pharmacist.

Your healthcare provider might slightly modify (change) your Clarinex treatment under the following situations:

People with kidney or liver problems: If you have kidney or liver impairment, your healthcare provider may need to adjust your dose.

Pregnant people: There is limited safety and effectiveness data about Clarinex in pregnant people. If you have any concerns, talk with your healthcare provider to weigh the benefits and risks of taking Clarinex during your pregnancy.

Nursing people: Experts expect low amounts of Clarinex in breast milk. As a result, experts believe that Clarinex is unlikely to cause negative effects on the nursing baby or milk production. Combining Clarinex with a decongestant—like Sudafed (pseudoephedrine), however, might negatively affect milk production.

Children: There is no safety and effectiveness information for Clarinex in children younger than 6 months.

Older adults: Some people over 65 may have medical conditions, such as liver and kidney impairment. Therefore, caution with Clarinex is recommended.

If you accidentally forgot your Clarinex dose, take it as soon as you remember. If it's already close to your next scheduled dose, then skip the missed dose and take the following dose at your next scheduled time. Don't try to double up to make up for the missed dose.

Daily high Clarinex doses of 45 45 milligrams (mg) for 10 days did not result in any side effects. If you accidentally take too much Clarinex, however, you might experience some drowsiness.

If you suspect you're experiencing life-threatening side effects, seek immediate medical attention.

If you think you or someone else may have overdosed on Clarinex, call a healthcare provider or the Poison Control Center (800-222-1222).

If someone collapses or isn't breathing after taking Clarinex, call 911 immediately.

If your symptoms do not improve within a few days or if they become worse, check with your doctor.

This medicine may cause some people to become drowsy, dizzy, or less alert than they are normally. Make sure you know how you react to this medicine before you drive, use machines, or do anything else that could be dangerous if you are dizzy or are not alert.

Before taking Clarinex, talk with your healthcare provider if the following applies to you.

Use caution when taking Clarinex with the following medications:

For more detailed information about drug interactions with Clarinex, talk with your pharmacist or healthcare provider.

There are many medications available to relieve allergy symptoms. Since Clarinex is a second-generation histamine (H1) antagonist, the following medications are most similar to Clarinex.

There are few studies that compare these different second-generation H1 antagonist medications. However, Xyzal and Zyrtec have the highest potency—with a moderate risk of sleepiness or drowsiness compared to the other medications in this class.

Except for Clarinex, all of the medications in this class are available as convenient over-the-counter (OTC) options. While insurance doesn't typically cover OTC products, it might cover Clarinex, which is a prescription medication.

Clarinex is also the only medication in the class approved to relieve allergy symptoms and treat chronic idiopathic hives. Additionally, Clarinex is the only medication in the class approved for children as young as 6 months.

Clarinex is available as a prescription from your healthcare provider. Many local retail pharmacies carry Clarinex. If necessary, pharmacy staff can usually order this medication for you.

Clarinex is a prescription. Without insurance, it tends to be more expensive than other over-the-counter medications in its class. However, since it has a generic version, this will help with the cost.

If Clarinex doesn't work for you, switching to another medication in its class might work. Talk with your pharmacist or healthcare provider about your symptoms. For example, if you have mainly allergy symptoms of the nose, then a steroid nasal spray might be a better option.

Allergy season can be a miserable time for many people, and living with chronic idiopathic hives can also be frustrating.

Taking Clarinex or other allergy-relieving medications may help. If you have allergy symptoms, avoiding exposure to triggers may also help. For example, avoid contact with pets if you're allergic to pet dander. You can also wear a mask or sunglasses outdoors to limit your exposure to allergens.

Verywell Health's drug information is meant for educational purposes only and is not intended as a replacement for medical advice, diagnosis, or treatment from a healthcare provider. Consult your healthcare provider before taking any new medication(s). IBM Watson Micromedex provides some of the drug content, as indicated on the page.

Food and Drug Administration. Clarinex label.

MedlinePlus. Histamine: the stuff allergies are made of.

Centers for Disease Control and Prevention. Allergies and hay fever.

American Osteopathic College of Dermatology. Urticaria.

Zuberbier T, Aberer W, Asero R, et al. The EAACI/GA2LEN/EDF/WAO guideline for the definition, classification, diagnosis and management of urticaria. European Journal of Allergy and Clinical Immunology. 2018;73(5):1145-1146. doi:10.1111/all.13414

Bernstein JA, Lang DM, Khan DA, et al. The diagnosis and management of acute and chronic urticaria: 2014 update. The Journal of Allergy and Clinical Immunology. 2014;133(5):P1270-1277. doi:10.1016/j.jaci.2014.02.036

Trautmann A, Anders D, Stoevesandt J, et al. H1-antihistamine premedication in NSAID-associated urticaria. The Journal of Allergy and Clinical Immunology: In Practice. 2016;5(6):P1205-1212. doi:10.1016/j.jaip.2016.05.018

Randall KL, Hawkins CA. Antihistamine and allergy. Austrialian Prescriber. 2018;41(2):41-45.

Smith N, Schellack N. Long-term antihistamine therapy revisted. South African Pharmaceutical Journal. 2015;82(8):12-16.

Simon FER, Simons KJ. H1 antihistamines: current status and future directions. World Allergy Organization Journal. 2008;1(9):145-155. doi:10.1186/1939-4551-1-9-145

Seidman MD, Gurgel RK, Lin SY, et al. Clinical practice guideline: allergic rhinitis. Otolaryngology-Head and Neck Surgery. 2015;152(1):S1-S43. doi:10.1177/0194599814561600

Food and Drug Administration. Allegra label.

Food and Drug Administration. Claritin label.

Food and Drug Administration. Xyzal label.

Food and Drug Administration. Zyrtec label.

Food and Drug Administration. Children's Zyrtec chewable tablets label.

Food and Drug Administration. Childrens Allegra label.

Food and Drug Administration. Childrens Xyzal label.

By Ross Phan, PharmD, BCACP, BCGP, BCPS Ross is a writer for Verywell with years of experience practicing pharmacy in various settings. She is also a board-certified clinical pharmacist and the founder of Off Script Consults.

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