Key Takeaways

Cetirizine is among the second-generation antihistamines that relieve the symptoms of allergy and urticarial hives.
It is less sedating than the first-generation antihistamines, but still makes certain people drowsy.
Reports of drowsiness by patients consuming cetirizine have been noted in 10% to 14% of the cases, according to clinical studies.
The probability of sleepiness is increased if cetirizine is consumed together with alcohol, as well as with medications for sedation and sleep.
If cetirizine makes you drowsy, consult your healthcare professional to get another medication for allergies.

What Is Cetirizine?

It is an Antihistamine that you can get without a prescription. It is used to stop or alleviate the symptoms of allergies that include, and are not limited to, the following:

sneezing
runny noses
itchy noses
eyes that are watery or itchy
itching or hives of the skin (urticaria)

It prevents the actions of histamine, which is a substance the immune system of a person releases in reaction to an allergy.

First-generation antihistamines cause a lot of drowsiness. Therefore, cetirizine, as a second-generation antihistamine, is said to have less sedative properties and antihistamine action which is effective.

Does Cetirizine Make You Sleepy?

Yes, cetirizine can cause drowsiness. However, this is not a universal side effect of cetirizine.

It is thought that it may cause drowsiness in some people, as a small amount of this drug crosses the blood-brain barrier. Most people take this drug with a good tolerance. The remaining people may experience the following:

Drowsiness
Fatigue
Delay in the response to stimuli
Decreased concentration

The aforementioned symptoms may be experienced with different degrees of severity based on the age of the person, the dose of the drug, individual body chemistry and other drugs taken concurrently with cetirizine, if any.

How Common Is Drowsiness with Cetirizine?

The consumption of the allergy medicine has been found to cause drowsiness, and this has been reported in most

Adults Reporting Drowsiness 10% – 14%
Most Common Side Effect Sleepiness, Fatigue
Severe Drowsiness Rare
Most People Able to Continue Treatment Yes

Compared to other older antihistamines, it is less likely to cause sedation. But it’s more likely to be sedating than other newer antihistamines such as loratadine.

Also Read : Can Amoxicillin Make You Tired?

Why Does Cetirizine Cause Sleepiness?

Histamine plays a role in an allergic response and in the regulation of wakefulness.

Since the allergy medicine is a histamine blocker, it relieves allergy symptoms; however, in some individuals, the blocking of histamine may also mean a reduction of alertness, thus causing fatigue.

The likelihood of feeling sleepy is determined by many factors and some of these may include:

Individual Sensitivity
Age
Liver and Kidney Function
Dose Taken
Use of Alcohol
Use of Other Medications

While some individuals may not experience fatigue with cetirizine use, others may experience it with every dose.

Who is More Likely to Feel Sleepy?

The following groups of people are at a greater risk of experiencing drowsiness with the allergy medicine:

Older Adults
Those Using Sedatives
Users of Anxiety Medications
Those Using Opioid Pain Medications
Dippers of Alcohol
People with Kidney Disease
People Taking Higher Than Recommended Dosages

If you are in one of the above groups, talk to your doctor before taking cetirizine regularly.

When does Sleepiness Usually Start?

Typical timeline:

Time After Taking Cetirizine	What Happens
20–60 minutes	The medicine begins to work and allergy symptoms start improving.
About 1 hour	Cetirizine reaches its highest level in the bloodstream.
1–3 hours	If drowsiness occurs, it is usually most noticeable during this period.
6–12 hours	Sleepiness often becomes milder in many people while allergy relief continues.
Up to 24 hours	The medication continues providing allergy relief with once-daily dosing.

Many people choose to take cetirizine in the evening if it consistently makes them sleepy.

Can You Drive After Taking Cetirizine?

Most healthy adults can perform normal daily activities, including driving, after taking this medication.

First time taking this? Avoid…

Driving
Operating heavy machinery
Climbing ladders
Anything that could be called a dangerous job.

Do this until you know how your body responds to cetirizine.

If sedated noticeably, It should be treated as a sedating drug, so do not participate in activities that require full attention.

What Makes Cetirizine Sleepiness Worse?

All of the following drugs will make cetirizine more sedating.

Alcohol
Sleeping pills
Opioid pain medications
Muscle relaxants
Anti-anxiety medications
Certain antidepressants

These drugs will cause increased sedation, increased dizziness, and increased coordination impairment.

How Does Cetirizine Compare with Other Allergy Medicines?

No, for most medications, first-generation antihistamines will be way more sedating than second-generation antihistamines.

Allergy Medicine	Generic Name	Generation	Likelihood of Sleepiness	Duration of Action
Zyrtec	Cetirizine	Second-generation	Moderate (10–14% of users)	Up to 24 hours
Claritin	Loratadine	Second-generation	Low	Up to 24 hours
Allegra	Fexofenadine	Second-generation	Very low (least sedating)	Up to 24 hours
Xyzal	Levocetirizine	Second-generation	Moderate	Up to 24 hours
Benadryl	Diphenhydramine	First-generation	Very high	4–6 hours
Chlor-Trimeton	Chlorpheniramine	First-generation	High	4–6 hours

If drowsiness is a concern, there are other antihistamines that will not cause drowsiness that we can recommend.

Tips to Reduce Sleepiness

this medication may make you tired, but you can combat that by doing the following.

Take it at night
Avoid alcohol
Stay hydrated
Get enough rest
Take the prescribed amount, and not more.
If Sleepiness Remains, Speak with Your Doctor

Do not take it upon yourself to change the prescribed dose.

When Should You Call Your Doctor?

You should get medical advice if…

You are excessively sleepy
You struggle to stay awake
You are confused
You lose consciousness
These symptoms affect your ability to drive or work
Your allergy symptoms still persist.

Final Thoughts

this antihistamine has the long-term benefits of decreased drowsiness and quicker effectiveness at treating hives. Like other antihistamines, this medication will always be a little drowsy. This is especially true for the first doses, while drinking alcohol, or while mixing with other medications that will also increase drowsiness.

If cetirizine causes drowsiness, there is always the option to take it later in the evening. You also have the option of visiting your doctor. They may have ideas for other second-generation antihistamines. Also, make sure you take the medication like you are supposed to, in order to lessen the chances of drowsiness throughout the next day.