1 What is ceterizine?

Brand: Zyrtec, Alleroff, and Aller-Tec

Generic: Cetirizine

  • Cetirizine is a newer generation antihistamine, a medication used to treat allergy symptoms.
  • It helps in reducing the naturally produced chemical, histamine, in the body.
  • It does not prevent symptoms completely; it works only to provide relief from allergy symptoms on a temporary basis.

This medicine can be purchased from a pharmacist over the counter and is less expensive. However, one should not take more than 10mg of a dose per day, or else it can lead to an overdose. For children, it is better to consult a doctor before giving the medicine since it can cause drowsiness.

Cetirizine is a second, or newer, generation antihistamine, a medication that is used for treating allergy symptoms. It helps reduce histamine, a naturally occurring chemical in the body. Histamine is known to cause symptoms such as runny nose, congestion, itching, watering of the eyes, and sneezing. When the body comes in contact with an allergen, such as dust mites, pollen, dander, latex, etc., the body releases histamine, and Cetirizine blocks this chemical. This medication, as mentioned earlier, is used for treating allergy and cold symptoms, but it is also used to treat symptoms caused due to hives, including swelling and itching. However, the doctor can also use it to treat other conditions not mentioned above.

Cetirizine medicine can be bought over the counter without a prescription from the doctor. It is available in various forms, such as tablets, capsules, and syrup. This medicine is not costly. Cetirizine is mostly safe, but it is always better to be aware of its usage and precautions. One should note that Cetirizine does not help to prevent allergies, it is only used to provide relief from allergy symptoms.

Avoid using Cetirizine for treating hives that have bruised or blistered, those that have different or unusual colors, or those that don’t itch. Let the doctor know if you come across such types of hives.

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2 What to Know Before Using

There are certain things one should keep in mind and let the doctor know about since, if ignored or not treated in time, they can lead to side effects or worsening of the existing condition. Let the doctor know if any of the following applies to you:

  • If you are allergic to any of the ingredients in Cetirizine
  • If you suffer from any kind of medical condition, such as liver problems or a kidney disorder
  • If you are pregnant or planning to become pregnant
  • If you are nursing
  • In the elderly, the dosage would be smaller compared to others.
  • If you are taking any medications, whether prescription or over-the-counter, any herbs, vitamins, or dietary supplements. Be sure to mention if you are taking any of the following medications: anxiety medications, mental illness medications, medicines for colds or allergies, antidepressants, sleeping pills, theophylline, seizure or convulsion medication, sedatives, or tranquilizers.

Since Cetirizine is an over-the-counter medicine, one should ideally talk to the doctor to understand all the considerations before actually starting this treatment. If there are any questions about the symptoms or any other kind of medical condition, it should be brought to the doctor’s notice. The doctor can look for another alternative antihistamine or suggest a combination of drugs with Cetirizine, which would usually need a prescription.

Below are a few questions one can ask the doctor:

  • Is Cetirizine a good choice? What are the other options available other than Cetirizine?
  • How much and how should I consume Cetirizine?
  • What changes would I notice after starting Cetirizine?
  • Can Cetirizine be taken along with any other medicines or health conditions?
  • What are the risks associated with Cetirizine?

3 Usage, dosage, and during use

Cetirizine should be taken exactly as prescribed by the doctor or you can follow the directions mentioned on the medicine label. Avoid increasing or reducing the dosage without confirmation from the doctor, or else it can lead to side effects. Do not take this medicine for longer durations without recommendation from a doctor. Cetirizine can be taken with or without food. The Cetirizine chewable tablets should be chewed properly before swallowing. For the liquid solution, be sure to use a special measuring spoon before taking it. Store the medicine at room temperature, away from heat and moisture. Cetirizine generally needs to be taken just once a day, and it starts to work pretty soon. Children above two years of age and adults can take the syrup form of this medicine. The syrup comes in fruit flavors. Children above six years of age and adults can take the capsule and tablet forms as well.

If you miss a dose, take it as soon as you remember, however, if it is time for another dose, skip the missed one, or else it can lead to an overdose. Some of the overdose symptoms are nervousness, drowsiness, and restlessness. If the symptoms do not show any signs of improvement or become worse, let the doctor know at the earliest. One of the most common signs of a Cetirizine overdose is extreme drowsiness. However, in rare cases, drowsiness can lead to sedation.

There have been instances of deep sedation in adults who ingested more than 150mg of the medicine. This is almost 15 times more than the recommended daily dose for an adult. In younger children, the medicine is known to be very sensitive, since it can impact them easily by inducing extreme drowsiness. In certain cases of a Cetirizine overdose, an individual may start to become restless and very irritable before experiencing drowsiness. One should note that Cetirizine-D, which is a combination medicine, can lead to adverse side effects if taken beyond the recommended dose. The symptoms can include irregular heart rhythm and palpitations.

Keep this medicine out of the reach of children. Lock the safety caps of the medicine immediately after using and store the container in a safe location.


Cetirizine is available in strengths of 10mg and 5mg. The normal dosage for adults who are below the age of 65 and children who are above age six is 10mg every day. In the span of 24 hours, you should not take more than 10mg of medicine. If the allergy symptoms are mild, the doctor can recommend to split the dose and take it twice a day at 5mg each.

It is advisable to speak to a doctor about dosing for children who fall in the age bracket of two to six years, elderly adults above the age of 65, and those who suffer from kidney problems and liver disease.

The dose for adults suffering from allergic rhinitis and urticaria can be 5mg to 10mg once a day, but the maximum dose should not go above 10mg per day. Patients who are above 65 years of age should start with 5mg per day just once. This medicine will provide relief from symptoms associated with perennial allergic rhinitis caused by allergens.

The pediatric dose for allergic rhinitis and urticaria is as follows:

  • Infants who are above six months to two years: The initial dose should be 2.5mg just once a day. The maintenance dose should be 2.5mg orally, to be given two times a day. The maximum dose should not exceed 5mg per day.
  • Children who fall in the age bracket of two years to five years: The initial dose should be 2.5mg just once a day. The maintenance dose should be 2.5mg orally, to be given two times a day, or it can be 5mg once a day. The maximum dose should not exceed 5mg per day.
  • Children above six years: The initial dose should be 5mg to 10mg, to be given orally once a day, and the maximum dose should not exceed 10mg per day.

During Use

Cetirizine can lead to impairment in thinking or reactions, so be careful if you have to drive since it requires mental alertness. It is thus advisable in such situations to avoid carrying out any activity that needs one to be mentally alert. Also, avoid consuming alcohol since it can lead to an increased risk of side effects. Cetirizine can cause sleepiness, so, if you are taking any other medicines that also make you feel sleepy, let the doctor know. A few such medicines include allergy medicine, narcotic pain medicine, muscle relaxers, seizure medicines, cold medicines, sleeping pills, and medicines for depression and anxiety.

If the hives for which you are using Cetirizine do not heal or improve during the first three months of treatment, or if the hives last longer than six weeks, you can gradually stop the medicine and let the doctor know. If the doctor has provided Cetirizine to treat the hives, but it starts to develop any severe symptoms, get emergency help immediately. Such symptoms include difficulty swallowing, breathing, or speaking; swelling in and around the mouth or on the tongue; constant drooling; drowsiness; and sudden loss of consciousness. These symptoms could be related to a life-threatening allergic reaction known as anaphylaxis. This is a serious issue that should not be ignored. If the doctor suspects you are suffering from anaphylaxis with the hives, they may prescribe an epinephrine injection, or EpiPen. In such instances, do not use Cetirizine in place of an epinephrine injection.

4 Drug interactions

Cetirizine is known to interact with certain medicines or substances. Do not consume alcohol while taking Cetirizine, as it can be fatal. Mixing alcohol with Cetirizine can lead to drowsiness or can make a person less alert when carrying out tasks. If you are using any kind of sedative, sleeping pills, or tranquilizer, inform the doctor before starting Cetirizine since, if these drugs are mixed with Cetirizine, it can depress the central nervous system, thus increasing the issue of sedation. Also, it can further cause problems by impairing the functioning of the mental and nervous systems.

Cetirizine along with theophylline can also cause a drug interaction. Theophylline is a drug taken by individuals suffering from asthma or other lung problems.

Cetirizine-D is basically a combination medicine under the brand name Zyrtec-D. The “D” in this case stands for “decongestant,” as the drugs are known to contain both the antihistamine effect of Cetirizine and the decongestant pseudoephedrine. If you suffer from any of the below conditions, avoid using Cetirizine-D and let the doctor know:

  • Diabetes
  • Heart-related disorder
  • High blood pressure
  • Thyroid irregularity
  • Glaucoma
  • Prostate enlargement along with urinary retention

5 Potential side effects

Unlike the first or old generation of antihistamines, Cetirizine is known to cause fewer side effects. Below are the serious side effects which should be told to the doctor if any appear:

  • Any kind of allergic reaction to the medicine, with symptoms such as hives, swelling of the lips, face, and throat, and difficulty breathing
  • Trouble with vision or blurry vision
  • Feeling very restless
  • Weakness or fatigue
  • Uneven heartbeat
  • Shaking that cannot be controlled or tremors
  • Lack of sleep or insomnia
  • Feelings of confusion
  • Trouble while urinating, less urine than normal, or no urine at all

Less severe side effects include drowsiness, nausea, dryness in the mouth, tiredness, headache, sore throat, constipation, dizziness, and cough. Most of the time, these symptoms are mild and go away in a couple of days. However, if the symptoms worsen or remain for a longer duration, let the doctor know.