Allergies Common Treatments Allegra vs. Zyrtec vs. Claritin: How Do They Compare? These antihistamines offer varying degrees of allergy symptom relief By Daniel More, MD Updated on April 11, 2024 Medically reviewed by Jurairat J. Molina, MD Print Table of Contents View All Table of Contents Symptoms Sleepiness Dosage Side Effects Interactions Allegra (fexofenadine), Zyrtec (cetirizine), and Claritin (loratadine) are over-the-counter (OTC) antihistamines. These allergy pills are used to treat hives, itchy skin, post-nasal drip, and other seasonal allergy symptoms caused by exposure to allergens (such as grass or tree pollen) that trigger an immune response (antibodies) in your body. When comparing Allegra, Zyrtec, and Claritin, remember that: Allegra is less likely to make you drowsy. Zyrtec and Allegra work faster than Claritin. All three work well to treat hives and symptoms of hay fever. This article compares Allegra, Claritin, and Zyrtec by looking at how quickly they work, recommended dosages, and side effects. In addition, it details how these medications might be used during pregnancy at the discretion of a healthcare provider. Shannon Fagan / Getty Images Allegra vs. Zyrtec vs. Claritin: The Symptoms They Relieve Allegra, Zyrtec, and Claritin are all over-the-counter antihistamines. Exposure to an allergen such as pet dander, dust mites, or pollen prompts the immune system to release chemicals called histamines. Antihistamines like Allegra, Zyrtec, and Claritin work by blocking histamines and calming your allergic response. Symptoms Relieved by Allegra, Claritin, and Zyrtec Allegra Claritin Zyrtec Runny nose X X X Sneezing X X X Itchy Eyes X X X Itchy throat X X X Hives X X X Zyrtec and Allegra both work quickly for the treatment of allergic rhinitis and hives, typically within less than an hour. You can take Claritin right away when symptoms start, but not more than once or twice per day, depending on the product. Claritin is a non-drowsy formula and similar to Allegra. Both may be preferable for mild to moderate allergy symptoms since other drugs are more sedating. For severe symptoms that are interfering with work, school, or play, a medication such as Zyrtec may be needed. It all depends on how much symptom relief you need and the degree of side effects you can tolerate. Many people do not experience any fatigue on Zyrtec; others report fatigue with Allegra. Allergy symptoms vary so if OTC allergy medications don't work for you, try another or consider seeing an allergist—an allergy specialist. They can determine the next steps, which may include allergy shots. Allegra vs. Zyrtec vs. Claritin: Which Makes You Sleepier? First-generation antihistamines such as Benadryl cross the blood-brain barrier, which can produce a sedative effect. This happens because histamines found in the brain also play a role in keeping you awake. Second-generation antihistamines like Allegra, Zyrtec, and Claritin, don't cross this barrier, so they are less likely to make you feel drowsy. Claritin and Allegra are non-sedating, meaning unlikely to make you sleepy. Zyrtec, on the other hand, can cause sedation in a minority of people who take it (about one in six). People who are over 60 years old may be more likely to experience sedation. Zyrtec is more likely to make you sleepy at night than Allegra or Claritin, but poor sleep quality is generally a side effect of all antihistamines. Avoid taking both Claritin and Zyrtec together, due to stronger side effects. Be sure to speak with your healthcare provider about potential drug interactions when you take antihistamines. Allegra and Zyrtec work best when taken at the same time each day, in order to make the most out of symptom relief. Claritin, when used only once a day, also should be taken around the same time. Zyrtec vs. Zyrtec-D for Allergies Drug Forms Antihistamines are available in several different over-the-counter products. They include: Allegra: Gel caps, tablets, dissolve tabs, and syrupClaritin: Tablets, chewables, syrup, liquid gels, dissolvablesZyrtec: Tablets, chewables, liquid gels, syrup, dissolvables Some options, including the chewables and syrups, are designed for children. Your pediatrician can help you to decide which products will work best for a child with allergies. Polypharmacy Concerns and Risks Allegra vs. Zyrtec vs. Claritin Dosage You should consult your healthcare provider about the best way to take any medication, but there are standard dosing recommendations for all three of these antihistamines. All of these antihistamines are indicated for adults and children 2 years old and older, with Zyrtec and Claritin dosed once a day for people of all ages. Allegra is dosed twice a day for children ages 2 to 11 and once a day for adults and children ages 12 and older. Allegra can be used in children as young as 6 months old. Allergy Treatments for Children Always Read Drug Labels Antihistamines are safe when they're used as directed. They can be dangerous when used improperly or carelessly. For example, some medications that contain antihistamines also contain pain medication. If a person is not aware of the types of medications included in a combination and is also taking another of the same type, an overdose could result. Comparing Side Effects: Allegra vs. Zyrtec vs. Claritin All three of these drugs can cause mild side effects, including headache, dizziness, stomach pain, and nausea. However, these drugs don't share all of the same potential side effects. It is possible, though uncommon, to have an allergic reaction to an antihistamine. Seek medical care at once if you experience symptoms like rash or hives, itching or angioedema (swelling of the face, throat, or tongue), or difficulty breathing after taking one of these medications. Side Effects of Allegra, Claritin, Zyrtec Allegra Claritin Zyrtec Body aches X Cough X X Rash, hives, itch X X Trouble breathing X X Trouble swallowing X X Edema (swelling) X Hoarseness X X Drowsiness X X Dizziness X Dry mouth X X Blurred vision X Red eyes X Sore throat X X Nervousness X Heart rate changes X Allegra vs. Zyrtec vs. Claritin: Possible Interactions Not all antihistamines are recommended for all people. If you're taking Allegra, it's important to avoid drinking fruit juice for one to two hours before you take the medication and one to two hours afterward. Juices such as orange juice or grapefruit juice can decrease the absorption of Allegra by nearly half. Other considerations when taking second-generation antihistamines include: A history of asthma, kidney, or liver disease A genetic phenylketonuria (PKU) diagnosis, which makes it important to avoid aspartame often found in dissolving drug tablets Whether you take other medications or supplements, especially cold and allergy drugs. People who take Theo-24 (theophylline), sedatives, and mental health medications like antidepressants when taking Zyrtec may need to have their dosages adjusted. A history of alcohol or substance use that may increase the risk of adverse effects Tell your healthcare provider about the use of erythromycin drugs or Nizoral (ketoconazole) when taking Allegra, and be sure to use any antacids a few hours before or after your medication. Pregnancy and Lactation During pregnancy and lactation, for example, Claritin and Zyrtec have an overall good safety profile in pregnancy, though research is limited. Zyrtec and Claritin are preferred during lactation over Allegra. Treating Allergies During Pregnancy Summary Claritin, Zyrtec, and Allegra are all good antihistamine options and are generally well-tolerated by many people. But some differences between them may make one of these antihistamines better for you than the others. For example, Zyrtec and Allegra may work faster than Claritin. Zyrtec and Claritin can make you sleepy, while Allegra usually won't. If you're unsure of which antihistamine to select, consult your healthcare provider or pharmacist. 8 Sources Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy. Fein MN, Fischer DA, O'Keefe AW, Sussman GL. CSACI position statement: Newer generation H1-antihistamines are safer than first-generation H1-antihistamines and should be the first-line antihistamines for the treatment of allergic rhinitis and urticaria. Allergy Asthma Clin Immunol. 2019;15:61. Published 2019 Oct 1. doi:10.1186/s13223-019-0375-9 Claritin. Claritin FAQ. MedlinePlus. Loratadine. American Academy of Allergy Asthma & Immunology. Antihistamines: If/when are first generation medications advantageous over newer antihistamines? Carnovale C, Battini V, Gringeri M, Volonté M, Uboldi MC, Chiarenza A, et al. Safety of fexofenadine and other second-generation oral antihistamines before and after the removal of the prescription requirement in Italy and other European countries: A real-world evidence study and systematic review. World Allergy Organ J. 2022 Jul 2;15(7):100658. doi: 10.1016/j.waojou.2022.100658. American Academy of Family Physicians. Antihistamines. National Capital Poison Center. Safe use of antihistamines. MedlinePlus. Cetirizine. Additional Reading Gonzalez-Estrada A, Geraci S. Allergy medications during pregnancy. Am J Med Sci. 2016;352(3):326-331. doi:10.1016/j.amjms.2016.05.030 U.S. Food & Drug Administration. Allegra (fexofenadine hydrochloride) tablets drug approval package. U.S. Food & Drug Administration. Claritin (loratadine/pseudoephedrine sulfate) ER tablets & Claritin (loratadine) tablets, syrup & RediTabs drug approval package. U.S. Food & Drug Administration. Zyrtec Allergy (cetirizine HCl) orally disintegrating tablets, 10 mg drug approval package. By Daniel More, MD Daniel More, MD, is a board-certified allergist and clinical immunologist. He is an assistant clinical professor at the University of California, San Francisco School of Medicine and formerly practiced at Central Coast Allergy and Asthma in Salinas, California. See Our Editorial Process Meet Our Medical Expert Board Share Feedback Was this page helpful? Thanks for your feedback! What is your feedback? 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