RxList.com states that users may experience constipation, dyspepsia (indigestion), flatulence (gas) and increased appetite 2.Rectal bleeding, melena (dark stools or vomit), tongue swelling and eructation (belching) are other gastrointestinal side effects. That's not as common with Zyrtec, but Boomershine says that 11 to 14 percent of people do report feeling sleepy after taking it, making it the most common side effect reported. Generally does not cause drowsiness, although more likely to do so at higher dosages. Other side effects are uncommon. 2. Children 6 months to 2 years of age: Irritability, fussiness, insomnia, fatigue, malaise. You may report them to the Use these dosage charts for infants and children under 12 years old:The easiest way to lookup drug information, identify pills, check interactions and set up your own personal medication records. If experienced, these tend to have a Less Severe expressionIf experienced, these tend to have a Less Severe expressionIf experienced, these tend to have a Severe expressionIf experienced, these tend to have a Less Severe expressionSelected from data included with permission and copyrighted by First Databank, Inc. Zyrtec (cetirizine)." Applies to cetirizine: oral solution, oral tablets and chewable tabletsSide effects include:Adults and children ≥12 years of age: Somnolence, fatigue, dry mouth. Cerner Multum, Inc. "Australian Product Information." Available for Android and iOS devices.We comply with the HONcode standard for trustworthy health information - Common side effects may include: dizziness, drowsiness; dry mouth; nausea, constipation; or; tired feeling. Read the entire detailed patient monograph for Zyrtec (Cetirizine) Serious Interactions. Zyrtec Side Effects. If you have mild side-effects, it is usually nothing to worry about. O 03. A headache, sore throat, abdominal pain, fatigue, drowsiness, or coughing. Hi A. Clark, Zyrtec is well tolerated by most children and adults. If experienced, these tend to have a Less Severe expression 1. Why? Side effects of Zyrtec fall into two categories: mild and severe. Pfizer US Pharmaceuticals, New York, NY. If they persist, you should call your doctor and let him or her know. Zyrtec is also associated with causing gastrointestinal (stomach or intestinal) problems. Insomnia reported with cetirizine (the active ingredient contained in Zyrtec) hydrochloride-pseudoephedrine hydrochloride fixed combination. Drowsiness 2. Consult your … Call your doctor for medical advice about side effects. This copyrighted material has been downloaded from a licensed data provider and is not for distribution, except as may be authorized by the applicable terms of use.Things to remember when you fill your prescription.WebMD does not provide medical advice, diagnosis or treatment. You may report side effects to FDA at 1-800-FDA-1088. Many people I spoke with for this story said they’d submitted complaints to the FDA about Zyrtec’s side effects. A search of the public dashboard of the FDA Adverse Effects Reporting System (FAERS) shows more than 14,000 cases reported of Zyrtec tablets since 1996; over 800 of those mention pruritus as the adverse reaction. Caution should be exercised before driving or operating machinery until full effects of Zyrtec are known. Does Zyrtec Interact with other Medications? This is not a complete list of side effects and others may occur. If you suffer from severe side-effects, seek immediate medical attention. O 0Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.Some side effects may not be reported. Along with its needed effects, cetirizine (the active ingredient contained in Some side effects of cetirizine may occur that usually Check with your health care professional if any of the following side effects The most commonly reported side effects include somnolence, 1. Cerner Multum, Inc. "UK Summary of Product Characteristics." "Product Information. These medications may interact and cause very harmful effects. Children 2–11 years of age: Headache, pharyngitis, abdominal pain. Answer. Warning On Zyrtec--don't Take If You're Over 65. Dry Mouth 3. Dryness Of The Nose 4. Throat Dryness