Is Zyrtec (cetirizine) safe to take during the first trimester of pregnancy?

Is Zyrtec (Cetirizine) Safe During the First Trimester of Pregnancy?

Cetirizine (Zyrtec) can be used during the first trimester of pregnancy, though it should be reserved for situations where the benefit justifies use, as it has reassuring safety data but is not the absolute first-choice antihistamine for this period. 1, 2, 3

Evidence-Based Safety Profile

The FDA drug label for cetirizine advises pregnant women to "ask a health professional before use," reflecting a cautious but not prohibitive stance. 4 This aligns with the broader evidence showing cetirizine is generally considered safe but requires clinical judgment.

Direct Safety Studies

• A prospective observational cohort study of 196 women exposed to cetirizine during the first trimester found no increased risk of major birth defects (OR 1.07; CI 0.21-3.59), spontaneous abortions (OR 0.97; CI 0.54-1.65), or preterm deliveries (OR 0.76; CI 0.35-1.5) compared to controls. 5

• An earlier prospective controlled study of 39 women exposed to cetirizine during organogenesis similarly found no significant differences in rates of live births, spontaneous or therapeutic abortions, stillbirths, major or minor anomalies, birth weight, or gestational age compared to controls. 6

Clinical Recommendations and Positioning

Preferred Alternatives When Possible

The American Academy of Allergy, Asthma, and Immunology suggests that if antihistamine treatment is necessary during the first trimester, chlorphenamine (chlorpheniramine) is often chosen by clinicians because of its longer safety record. 1 Additionally, cetirizine and loratadine are classified as FDA Pregnancy Category B drugs with more accumulated safety data than levocetirizine (the active enantiomer of cetirizine). 1

When Cetirizine Is Appropriate

Multiple sources identify cetirizine as one of the second-generation antihistamines of choice during pregnancy:

• Cetirizine and loratadine are the most well-studied second-generation antihistamines and are generally considered safe throughout pregnancy. 3

• For allergic conditions in pregnancy, second-generation antihistamines of choice are cetirizine and loratadine. 2

• One source specifically notes cetirizine can be used in the third trimester, with loratadine preferred in the second and third trimesters, though this distinction appears less critical given the overall safety data. 7

Practical Clinical Algorithm

When managing allergic symptoms in the first trimester:

1. First, attempt non-pharmacological approaches including allergen avoidance and saline nasal rinses. 1

2. If medication is necessary and the patient requires an antihistamine:

   • Consider chlorpheniramine first due to its longest safety track record 1
   • Cetirizine is an acceptable alternative, particularly if the patient has previously responded well to it or if sedation from first-generation antihistamines is problematic 2, 3, 5

3. Avoid oral decongestants during the first trimester due to conflicting reports of association with gastroschisis and small intestinal atresia. 1

4. Consider intranasal corticosteroids (particularly budesonide) as an alternative or adjunct for nasal symptoms, as they have a favorable safety profile. 1, 2

Critical Caveats

• The first trimester (particularly weeks 3-10) represents the period of organogenesis and highest risk for medication-induced teratogenicity. 1, 8 This is why all medications should be used judiciously during this window.

• Do not combine cetirizine with oral decongestants during the first trimester, as the combination of decongestants with other medications may increase malformation risk. 1

• Hydroxyzine (a related first-generation antihistamine and parent compound of cetirizine) should be specifically avoided during early pregnancy based on animal data showing potential risks. 1

Bottom Line for Clinical Practice

Cetirizine has reassuring human safety data from prospective studies showing no increased teratogenic risk when used in the first trimester. 5, 6 While chlorpheniramine may be marginally preferred due to its longer historical use, cetirizine represents a reasonable choice when antihistamine therapy is medically necessary, particularly when second-generation antihistamines are preferred to avoid sedation or when the patient has established efficacy with this agent. The key is ensuring the benefit of symptom control justifies medication use during this critical developmental window.