How Long Does Cetirizine Stay in Your System?

Do you suffer from sneezing, eye watering, or itching around certain allergens? You may have heard of a medication called cetirizine. So what is cetirizine? These over-the-counter antihistamines are very easy to find and highly effective at relieving those horrible allergy symptoms. In this article we discuss questions like “how long does cetirizine stay in your system?” and “can cetirizine make you drowsy?”. Read on to find out more as we answer some commonly asked questions about cetirizine.

How does cetirizine work?

Before we get into how this medication works, let’s go through the uses of cetirizine tablets. Cetirizine is a type of antihistamine. This type of medication is typically used to relieve symptoms of allergies such as itchiness, sneezing, hives, or watering eyes. What causes these symptoms is a chemical called histamine which is released in your body when you come into contact with something you are allergic to e.g pollen, dust. As the name suggests, antihistamines work by blocking histamine receptors in your body. By blocking these receptors, the medication helps to relieve symptoms and reduce the hypersensitive response (e.g sneezing, hives etc.) to the allergen. Follow this link to read more about other allergy medications.

How long does cetirizine stay in the body?

How long cetirizine stays in the body can vary depending on individual factors such as pre-existing medical conditions. For example, the half life of cetirizine (the time it takes for the concentration of the medication to decrease by half) is around 7-10 hours. However, if you have a kidney problem, the cetirizine half life could extend to 20 hours. So how long does cetirizine take to work? Generally, you should begin to feel a relief in allergy symptoms within one hour of taking cetirizine and it typically lasts for around 24 hours in the body. This means that in situations where you are aware you might encounter the allergen frequently e.g pollen season, you may need to take cetirizine daily.

Factors that affect how long cetirizine stays in the system

There are many factors that may affect how long cetirizine stays in your system, for example:

• Age: Medication can often be processed more slowly in older adults
• Kidney function: If you have a kidney problem, this may also affect how quickly medication like cetirizine is cleared. This might mean it takes the body more time to clear cetirizine so the medication stays in your body for longer
• Dose: A higher dose of medication might need more time to be cleared from the body. The maximum dose of cetirizine in 24 hours is one 10mg tablet for adults and children above the age of 12. For children under 12, please consult your healthcare provider for more specific advice on dosage.
• Metabolism: There can also be considerable variation between individuals in how their body processes medication

Does cetirizine accumulate in the body?

No, if you follow the instructions about the recommended cetirizine dosage then cetirizine does not usually accumulate in the body. However, if you take too much cetirizine or you have a kidney problem that affects the clearance of the medication, then it is possible that cetirizine can build up in the body.

Can cetirizine show up in tests (blood, urine)?

Yes, if you are due for a blood test or urine test, cetirizine can be detected although identification of this drug does not typically form part of any routine urine test or blood test. To detect cetirizine the sample would have to be sent to a lab to be specifically measured. Cetirizine is not considered a drug of abuse so if a workplace conducts drug test screening, cetirizine will most likely not be part of the drug screen. However, as we will go on to discuss, cetirizine use can affect certain clinical tests so if you are unsure if you need to stop your medication before a test, please consult your healthcare provider for more specific advice.

In what cases can antihistamines affect tests?

As mentioned above, there are some situations where taking antihistamines can affect clinical tests. The most notable case is an allergy skin test. This type of test is used to assess what allergens you might be hypersensitive to, thus if you are taking antihistamines, the medication might suppress your response and produce inaccurate results of what you are allergic to. Therefore, it is common practice for clinicians to advise you to stop taking antihistamines in preparation for an allergy skin test. If you are due for an allergy skin test, please consult your healthcare provider about when to stop your antihistamines before the test.

Side effects and how long they last

Although cetirizine is typically well tolerated and low risk, it is still a medication and thus there are still some possible side effects to be aware of, for example:

• dry mouth
• feeling mildly drowsy
• dizziness
• headaches

If these side effects persist and affect your day to day activities, please consult your healthcare provider for advice.

Tips for using cetirizine safely

To minimise your risk of size effects for cetirizine and optimise the effectiveness of the medication, here are some tips you can follow:

• Follow the instructions on the package (or your doctor’s instructions). Do not take any more than the recommended dose (e.g one tablet a day for adults).
• Avoid alcohol. Cetirizine is considered a ‘non-drowsy’ antihistamine, however, drinking alcohol while taking cetirizine may lead to heightened drowsiness and dizziness.
• Although Cetirizine is considered ‘non-drowsy’, medication can affect individuals differently. Some people may feel drowsy on cetirizine. For your own safety and others, make sure you check how this medication affects you before you operate any heavy machinery or drive.
• If you have a kidney problem, this may affect how your body clears cetirizine. Please consult your healthcare provider before taking this medication.

Why is it important to consider individual factors

It is important to consider individual factors (e.g history of kidney problems, age, metabolism etc.) because it can have a significant influence on the safety and effectiveness of cetirizine. Notably, these factors can affect the processing and clearance of the medication which in turn means that elements like the duration of cetirizine’s effect can also vary between individuals. If you have any further concerns or questions specific to your situation, please consult your healthcare provider.