What are the side effects of Cetirizine?

Users most often report drowsiness, fatigue, itching, withdrawal, rebound. Side effects came up 9 times across 33 reports.

User reports can't establish safety. PubMed lists 45 meta-analyses and 400 randomized trials. Talk to a doctor or pharmacist, especially if you take other medication.

Cetirizine side effects

Across 33 first-hand reports, people mentioned a side effect 9 times (about 27 per 100 reports). The most common: drowsiness, fatigue, itching. User reports show what people notice — they can't tell you whether Cetirizine is safe for you.

Reported side effects

drowsiness5

fatigue1

itching1

withdrawal1

rebound1

In their own words

“Cetirizine Hydrochloride/ZIRTEK... I get this no-nonsense attitude and feeling of focused... the next morning i'm feeling slightly groggy”

MixedRead the discussion ↗

“I tried zertec and anti acids, nothing helps so far.”

Didn't helpRead the discussion ↗

“H1 antagonists (e.g. cetirizine) give me symptoms that feel extremely similar to those I experience naturally when not taking Methylphenidate.”

Read the discussion ↗

“I went from being a B and C student, to a straight A student in all honors classes, without even trying.”

MixedRead the discussion ↗

“High dose Zyrtec definitely gave me a huge rebound before switching. ... I'm taking Zyrtec daily since a long time, and it seems to not work as well as before.”

Didn't helpRead the discussion ↗

“I've tried Zyrtec and that makes me drowsy”

Didn't helpRead the discussion ↗

Is Cetirizine safe? What the research covers

AResearch: Strong45 meta-analyses · 400 randomized trials on PubMed

J Asthma · 2025

Efficacy and safety of montelukast-levocetirizine combination therapy in combined allergic rhinitis and asthma syndrome: a systematic review and meta-analysis

Conclusion: In summary, this meta-analysis demonstrated the efficacy of montelukast combined with levocetirizine in the treatment of nasal symptoms in AR with asthma, indicating that the combination of montelukast with levocetirizine is more effective in improving symptoms of allergic rhinitis than monotherapy and has good safety.