How It Works
Histamines are chemicals released by your immune system when an allergic trigger is detected. After binding to H1 receptors, histamines signal the body to produce itching, inflammation, mucus production, and other defenses against the allergen.
Cetirizine works by blocking H1 receptors and preventing histamines from binding to them. This helps reduce allergy symptoms caused by histamines, such as a runny nose or itchy eyes.
| Quick Facts | |
|---|---|
| Common Brands | Zyrtec |
| Drug Class | Antihistamine |
| Generic Status | Generic version available |
| Availability | OTC and prescription |
Dosing
Patients typically take cetirizine once per day because the medication is formulated to provide 24 hours of allergy symptom relief. However, each formulation has different administration guidelines.
- Standard dose: Depending on symptom severity, the standard cetirizine dose for adults is 5-10 mg per day. The maximum recommended daily dose is 10 mg.
- Non-chewable tablets and capsules: Patients are advised to swallow cetirizine tablets and capsules whole with water.
- Orally disintegrating tablets: Per standard guidelines, patients are instructed to place a disintegrating tablet on their tongue and allow it to dissolve completely. These tablets may be taken with or without water.
- Chewable tablets: Standard guidelines recommend fully chewing or crushing these tablets before swallowing.
- Liquid: A calibrated oral syringe or medication cup is recommended for these doses, as household spoons are not a reliable measure for medication.
Note: The dosing information below is for educational purposes only. Your prescribing physician will determine your specific dose based on your individual health needs. Always follow your healthcare provider’s instructions for exact dosing.
Uses
FDA-Approved Uses
Cetirizine is FDA-approved to treat seasonal and perennial (year-round) allergy symptoms of allergic rhinitis, including sneezing, runny nose, and itchy or watery eyes. The medication is also FDA-approved to relieve itching and reduce the size and number of hives associated with chronic urticaria.
Off-Label Uses
You may see cetirizine prescribed for uses that are not “FDA-approved.” This is a very common and legal practice called “off-label” prescribing, where a doctor uses their clinical judgment to prescribe a drug for a different (but well-researched) purpose.
Common off-label uses for cetirizine currently found in clinical research and practice include:
- Management of atopic dermatitis: Providers may prescribe cetirizine off-label to relieve the intense itching associated with eczema.
- Acute allergic reaction: Doctors may use cetirizine to manage mild skin reactions caused by an allergic reaction.
Side Effects
Patients generally tolerate cetirizine well, but side effects can still occur.
Common Side Effects
Common side effects of taking cetirizine include:
- Drowsiness or fatigue
- Dry mouth
- Headache
- Nausea or vomiting
- Diarrhea
Serious Side Effects
Serious side effects are rare, but it’s important to know what to look for if they do occur. Serious side effects of taking cetirizine can include:
- Bronchospasm: In rare instances, people taking cetirizine may experience airway tightness and difficulty breathing.
- Accidental overdose: Signs of taking too much cetirizine include rapid heart rate, hallucinations, extreme irritability, and extreme drowsiness. This is considered an emergency that requires immediate medical attention.
- Severe allergic reaction: As with many medications, cetirizine can trigger a severe reaction in people allergic to one or more of its ingredients. It is advised to seek help immediately if you experience difficulty breathing, tightness in the throat, or swelling of the face, lips, or tongue.
Call your doctor immediately if you experience any concerning or prolonged symptoms.
Pharmacist Tips
Timing Is Key
Since cetirizine may cause drowsiness, pharmacists and doctors often recommend taking your daily dose before bedtime. However, the drug can safely be taken any time of day depending on when you experience the most intense allergy symptoms.
Consistency Matters
Per standard guidelines, taking cetirizine once per day as a maintenance medication for chronic allergies is usually more effective than taking the drug on an “as needed” basis for acute symptoms.
Avoid Other Antihistamines
Do not combine cetirizine with other antihistamines unless specifically directed to do so by a healthcare professional. Doubling up on antihistamines increases your risk of side effects like extreme drowsiness and confusion.
Watch For Drowsiness
Although cetirizine is formulated to cause less drowsiness than older antihistamines, you may still feel tired after taking the medication. This is crucial if you need to drive or operate machinery close to your regular dosage time.
Withdrawals Can Occur
Some people report intense itching after stopping long-term use of cetirizine. If you have taken the medication for an extended period of time, your provider may recommend a gradual tapering to minimize rebound symptoms.
Drug Interactions
Researchers have noted some interactions between cetirizine and other medications and substances. Known interactions with cetirizine include:
- Central nervous system depressants: Medications for anxiety, sleep, and pain can intensify the sedative effects of cetirizine and make you feel drowsier. The same is true of alcohol.
- Theophylline: Cetirizine may interact with this asthma medication, which can increase the patient’s risk of adverse side effects.
Always give your doctor and pharmacist a complete list of all your medications, vitamins, and supplements to check for potential interactions.
FAQs
Why does cetirizine make me feel sleepy and groggy when it is supposed to be a “non-drowsy” allergy pill?
Second-generation antihistamines like cetirizine are formulated to cause less drowsiness than their predecessors. However, individual experiences with cetirizine vary, and some people experience drowsiness after taking the drug.
How quickly does cetirizine take to stop my sneezing, runny nose, and itchy eyes?
Cetirizine is known for acting quickly. For many people, the medication begins working within 20 to 60 minutes of administration.
Is it true that stopping cetirizine after taking it for months can cause full-body itching?
Yes, stopping cetirizine after taking it for months can cause full-body itching. This is a rebound effect. Your provider may recommend a gradual tapering schedule, rather than quitting the drug abruptly to reduce rebound symptoms.
Should I take my daily cetirizine pill in the morning, or right before I go to bed?
Doctors often recommend taking cetirizine before bed in case the medication causes drowsiness. However, standard guidelines state patients can safely take the drug any time of day.
Is it safe to drink alcohol while taking cetirizine?
Providers typically recommend avoiding or limiting alcohol consumption while taking cetirizine. Alcohol can heighten cetirizine’s sedative effects and lead to excessive drowsiness.
Can I safely use a steroid nasal spray like Flonase on the same day I take cetirizine?
Yes, it is considered safe to use a steroid nasal spray like Flonase on the same day you take cetirizine. Doctors may recommend taking both for comprehensive allergy management, but it is recommended to speak with your provider before adopting this regimen.
Can I take over-the-counter pain meds like ibuprofen or Tylenol at the same time?
Yes, standard guidelines state it is acceptable to take over-the-counter pain medications like ibuprofen or Tylenol at the same time as cetirizine. There are no major known interactions between cetirizine and these pain relievers.
Will this medicine help stop the swelling and itching from a bee sting, spider bite, or hives?
Cetirizine is approved to treat swelling and itching associated with chronic hives. It can also help manage itching symptoms from minor stings and bites from insects and spiders, but does not treat the actual severe sting or bite.
Does cetirizine interact with high blood pressure medications?
Cetirizine does not typically affect blood pressure. However, standard guidelines recommend exercising caution with combination allergy products like Zyrtec-D that combine an antihistamine with a decongestant that can elevate blood pressure.
Comparable Medications
Cetirizine, Loratadine, Levocetirizine, Zyrtec-D, or Fexofenadine?
Cetirizine is an antihistamine available over-the-counter and in a prescription strength for managing hay fever and chronic hives. Other anti-allergy medications are available, and your provider may recommend an alternative to cetirizine based on factors such as your age, medical history, and the severity of your allergy symptoms. Cetirizine alternatives include:
Loratadine Tablets
From $22.99
Another non-drowsy second-generation antihistamine, loratadine is sold under brand names like Claritin and Alavert. Cetirizine typically works faster, but loratadine is associated with a slightly lower incident rate of drowsiness as a side effect.
Levocetirizine Tablets
From $28.99
Sold under the brand name Xyzal, levocetirizine is chemically related to cetirizine and often prescribed as a refined version of the drug. This may allow for smaller doses to achieve the same results, but individual experiences with both drugs vary.
Zyrtec-D
This medication combines cetirizine with pseudoephedrine, a decongestant, to provide comprehensive relief of allergy symptoms. However, the decongestant component can raise blood pressure, so patients with hypertension or hypertension risk should consult with their provider before use.
Fexofenadine Tablets
From $22.99
Sold under the brand name Allegra, fexofenadine is even less likely to produce drowsiness than other "non-drowsy" antihistamines like cetirizine and loratadine. For this reason, fexofenadine may be recommended to people who have a hard time with the sedative effects of other anti-allergy medications.
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Important: Information on this page is for educational purposes only. Prescribing decisions are made by independent, licensed providers. TelyRx operates technology-enabled pharmacies and a telehealth platform that connects patients with licensed providers. Prescriptions, when provider-approved and issued, are filled and shipped by TelyRx-affiliated pharmacies. We do not employ physicians or make prescribing decisions. Learn more about our editorial standards here.