Fexofenadine
MedicationAllegra
Second-generation antihistamine
Research strength: 4 / 5
MotherToBaby reports that studies have not found an increased chance of birth defects and that one comparison found no difference in miscarriage chance. In the Danish registry cohort, Andersson and colleagues (2020) found major birth defects in 118 of 2,962 fexofenadine-exposed pregnancies (4.0%) and 112 of 2,962 matched cetirizine pregnancies (3.8%); the adjusted comparison did not show an increased risk. The same study's pregnancy-wide miscarriage analysis found 413 miscarriages among 4,901 fexofenadine pregnancies (8.4%) versus 439 of 4,901 matched cetirizine pregnancies (9.0%), with a hazard ratio of 0.93 (95% CI 0.82-1.07). Yamazaki and colleagues (2026) found 4 major birth defects among 217 fexofenadine-exposed singleton births (1.8%) and no significant increase, although the confidence interval was wide. NHS SPS says human pregnancy data are limited and reserves fexofenadine for cases with no other suitable treatment; the Allegra label says to ask a health professional before use when pregnant. Ask your provider about your situation.
Last reviewed: 2026-10-16
Sources
- MotherToBaby: Fexofenadine (Allegra)Teratology service
- Andersson et al., JAMA Pediatrics 2020 (Danish registry cohort)US government
- Yamazaki et al., Congenital Anomalies 2026 (Japanese first-trimester cohort)US government
- NHS Specialist Pharmacy Service: Hay fever or allergic rhinitis treatment during pregnancyUK government
- DailyMed: Allegra Allergy (Chattem) OTC Drug FactsDrug company label
Research strength: 3 / 5
MotherToBaby describes a comparative study as finding no increased chance of preterm delivery or low birth weight. The Danish primary study reported preterm birth and small-for-gestational-age outcomes, not low birth weight, and did not provide second-trimester-only estimates. The 2026 Japanese cohort assessed low birth weight after first-trimester exposure only, so it does not answer a second-trimester question. NHS SPS says human pregnancy data for fexofenadine are limited and it should be reserved for cases with no other suitable treatment. The Allegra label says to ask a health professional before use when pregnant. Ask your provider about your situation.
Last reviewed: 2026-10-16
Sources
- MotherToBaby: Fexofenadine (Allegra)Teratology service
- Andersson et al., JAMA Pediatrics 2020 (Danish registry cohort)US government
- Yamazaki et al., Congenital Anomalies 2026 (Japanese first-trimester cohort)US government
- NHS Specialist Pharmacy Service: Hay fever or allergic rhinitis treatment during pregnancyUK government
- DailyMed: Allegra Allergy (Chattem) OTC Drug FactsDrug company label
Research strength: 3 / 5
MotherToBaby describes a comparative study as finding no increased chance of preterm delivery or low birth weight. The Danish primary study reported preterm birth and small-for-gestational-age outcomes, not low birth weight, and did not provide third-trimester-only estimates. The 2026 Japanese cohort assessed low birth weight after first-trimester exposure only, so it does not answer a third-trimester question. NHS SPS says human pregnancy data for fexofenadine are limited and it should be reserved for cases with no other suitable treatment. The Allegra label says to ask a health professional before use when pregnant. Ask your provider about your situation.
Last reviewed: 2026-10-16
Sources
- MotherToBaby: Fexofenadine (Allegra)Teratology service
- Andersson et al., JAMA Pediatrics 2020 (Danish registry cohort)US government
- Yamazaki et al., Congenital Anomalies 2026 (Japanese first-trimester cohort)US government
- NHS Specialist Pharmacy Service: Hay fever or allergic rhinitis treatment during pregnancyUK government
- DailyMed: Allegra Allergy (Chattem) OTC Drug FactsDrug company label
Fexofenadine — Breastfeeding
Research strength: 2 / 5
MotherToBaby reports that small amounts pass into breast milk and are likely too low to cause problems. LactMed says milk levels have not been measured after fexofenadine itself; it uses terfenadine-derived milk data with typical fexofenadine serum levels to estimate infant exposure. A primary study in four mothers taking terfenadine measured an average peak metabolite level of 41 ng/mL and estimated maximum infant exposure at no more than 0.45% of the recommended maternal weight-corrected dose. NHS SPS recommends caution and infant monitoring, while LactMed does not expect adverse effects but notes a possible milk-supply effect, especially with pseudoephedrine. The Allegra label advises asking a health professional before use while breastfeeding. Ask your provider about your situation.
Last reviewed: 2026-10-16
Sources
- MotherToBaby: Fexofenadine (Allegra)Teratology service
- LactMed (NIH): FexofenadineUS government
- NHS Specialist Pharmacy Service: Using antihistamines during breastfeedingUK government
- Lucas et al., Clinical Pharmacology and Therapeutics 1995 (terfenadine milk pharmacokinetics)US government
- Ito et al., American Journal of Obstetrics and Gynecology 1993 (breastfed infant follow-up)US government
- DailyMed: Allegra Allergy (Chattem) OTC Drug FactsDrug company label
Pregnancy
Andersson et al. (2020) used Danish registry data on filled prescriptions and matched fexofenadine users 1:1 with cetirizine users. In the major birth-defect analysis, 118 of 2,962 fexofenadine pregnancies (4.0%) and 112 of 2,962 matched cetirizine pregnancies (3.8%) had a major defect; the prevalence odds ratio was 1.06 (95% CI 0.81 to 1.37). In the separate miscarriage analysis, 413 of 4,901 fexofenadine pregnancies (8.4%) and 439 of 4,901 matched cetirizine pregnancies (9.0%) ended in spontaneous abortion; the hazard ratio was 0.93 (95% CI 0.82 to 1.07). The study also assessed preterm birth, small-for-gestational-age, and stillbirth; it did not report low birth weight, and its outcome-specific analyses do not give second- or third-trimester-only estimates. Yamazaki et al. (2026) studied first-trimester exposure in a Japanese cohort. The major-defect analysis included 217 fexofenadine-exposed singleton births, with 4 defects (1.8%) and an adjusted odds ratio of 1.081 (95% CI 0.352 to 3.318). A May 2026 correction changed the reported control count from 1,056 to 966 and the total from 1,473 to 1,350. MotherToBaby states that studies of behavior or learning outcomes have not been done; the two cohorts measured pregnancy and birth outcomes, not later development.
Breastfeeding
MotherToBaby says fexofenadine passes into milk in small amounts. LactMed reports that milk levels have not been measured after fexofenadine itself. In a 1995 pharmacokinetic study, four lactating mothers took terfenadine 60 mg every 12 hours for 48 hours; mean peak fexofenadine-metabolite concentration in milk was 41.0 ng/mL (SD 16.4), and the authors estimated maximum newborn exposure at no more than 0.45% of the recommended maternal weight-corrected dose. LactMed estimates less than 0.1% of the maternal weight-adjusted fexofenadine dose using typical serum levels after fexofenadine; this is a different basis from the primary terfenadine study estimate. The 1993 prospective follow-up reported no major adverse reactions requiring medical attention among 838 breastfed infants and minor reactions in 8 of 85 infants exposed to antihistamines, including irritability in 6 of those 8. Those are class-level figures and the PubMed abstract does not isolate a fexofenadine- or terfenadine-specific subgroup. LactMed reports no relevant published infant serum-level information, and NHS SPS also says infant serum levels have not been measured. NHS SPS states that its recommendations apply to full-term, healthy infants.
Fexofenadine is an over-the-counter antihistamine used for allergy symptoms. MotherToBaby identifies Allegra as a brand name, and the current U.S. Allegra Allergy label lists fexofenadine hydrochloride as its active ingredient.
What was tested
The human pregnancy evidence reviewed includes a Danish registry cohort using filled-prescription records and a Japanese teratology-service cohort focused on first-trimester exposure. Both are observational, and the Japanese cohort had a small fexofenadine group in its main birth-defect analysis. The breastfeeding evidence includes a milk pharmacokinetic study after terfenadine, not direct fexofenadine dosing, plus a follow-up of infants exposed to several medication classes. No direct fexofenadine milk measurements or relevant infant serum-level data were reported in the sources reviewed.
How to rate fexofenadine in pregnancy when measured outcomes are reassuring but human data remain limited
- Source A says
- NHS SPS prefers cetirizine or loratadine and says fexofenadine should be reserved for cases where no other suitable treatment is available because human pregnancy data are limited. (NHS Specialist Pharmacy Service: Hay fever or allergic rhinitis treatment during pregnancy)
- Source B says
- MotherToBaby reports no increased chance of birth defects or miscarriage in the studies it summarizes. The Danish registry cohort and the 2026 Japanese cohort did not identify an increased risk in the outcomes they measured. (MotherToBaby: Fexofenadine (Allegra), Andersson et al., JAMA Pediatrics 2020 (Danish registry cohort), Yamazaki et al., Congenital Anomalies 2026 (Japanese first-trimester cohort))
- Why they differ
- The primary cohorts tested specific outcomes and exposure windows, while NHS SPS compares the amount of fexofenadine pregnancy experience with the larger experience for cetirizine and loratadine. The SPS recommendation is based on limited data, not an identified fetal harm.
- What the evidence shows overall
- Andersson et al. (2020) and Yamazaki et al. (2026) found no significant increase in their measured outcomes, but their results do not establish risk for every exposure window or later child development. NHS SPS states that its preference reflects limited human pregnancy data and greater experience with alternatives.
Expected infant effects and monitoring during breastfeeding
- Source A says
- MotherToBaby says milk amounts are likely too low to cause problems, and LactMed says adverse effects would not be expected based on low milk levels and lack of sedation. (MotherToBaby: Fexofenadine (Allegra), LactMed (NIH): Fexofenadine)
- Source B says
- NHS SPS says fexofenadine can be used with caution during breastfeeding, requires infant monitoring, and prefers cetirizine or loratadine. (NHS Specialist Pharmacy Service: Using antihistamines during breastfeeding)
- Why they differ
- Evidence is very limited and indirect: measured milk levels came from mothers taking terfenadine, and infant follow-up did not isolate fexofenadine exposure. NHS SPS uses monitoring as a precaution where infant data are limited.
- What the evidence shows overall
- MotherToBaby and LactMed do not expect infant effects at the low exposure described, while NHS SPS recommends monitoring as a precaution. The primary milk study involved terfenadine rather than direct fexofenadine dosing, so the available evidence remains limited.
Possible effect on milk production
- Source A says
- LactMed says fexofenadine might negatively affect lactation, especially with a sympathomimetic such as pseudoephedrine. (LactMed (NIH): Fexofenadine)
- Source B says
- NHS SPS reports limited and conflicting data, and says antihistamines at normal therapeutic doses are unlikely to affect milk production, especially once lactation is established. (NHS Specialist Pharmacy Service: Using antihistamines during breastfeeding)
- Why they differ
- The concern is based on limited information about antihistamines and prolactin rather than a fexofenadine-specific study measuring milk supply. NHS SPS states that evidence is limited and conflicting.
- What the evidence shows overall
- The sources do not establish a fexofenadine-related reduction in milk production. LactMed identifies a possible concern, especially with pseudoephedrine, while NHS SPS says normal therapeutic doses are unlikely to affect supply once lactation is established.
- NHS SPS describes allergen avoidance, a barrier ointment around the nostrils, and saline nasal irrigation as non-drug options during pregnancy; it says topical treatments can be considered when these measures are insufficient. (NHS Specialist Pharmacy Service)
- NHS SPS prefers loratadine or cetirizine during pregnancy and reserves fexofenadine for cases where no other suitable treatment is available. (NHS Specialist Pharmacy Service)
- NHS SPS says fexofenadine can be used with caution during breastfeeding, with infant monitoring; it prefers cetirizine or loratadine. (NHS Specialist Pharmacy Service)
- The U.S. Allegra label says to ask a health professional before use during pregnancy or breastfeeding. (DailyMed: Allegra Allergy (Chattem))
General research, not specific to pregnancy.
The current U.S. Allegra label says not to use the product after an allergic reaction to it or any ingredient. EMA's 2023 PRAC review recommended EU product-information changes for blurred vision, with frequency unknown, and an interaction with apalutamide that can lower fexofenadine exposure.
- The U.S. Allegra label says not to use the product if there has ever been an allergic reaction to it or any of its ingredients. (DailyMed: Allegra Allergy (Chattem) OTC Drug Facts)
- EMA's PRAC concluded that a causal relationship between fexofenadine and blurred vision was at least a reasonable possibility; the EU product information lists blurred vision at a frequency that cannot be estimated from available data. (EMA PRAC: Fexofenadine scientific conclusions and product-information variation)
- EMA reports that a clinical interaction study found a 30% decrease in fexofenadine AUC when apalutamide was co-administered with a single 30 mg fexofenadine dose, and recommended an EU product-information change. (EMA PRAC: Fexofenadine scientific conclusions and product-information variation)
- MotherToBaby: Fexofenadine (Allegra)Teratology serviceSecondary
- LactMed (NIH): FexofenadineUS governmentSecondaryPage dated 2025-09-15
- NHS Specialist Pharmacy Service: Hay fever or allergic rhinitis treatment during pregnancyUK governmentSecondaryPage dated 2025-01-31Independent check
- NHS Specialist Pharmacy Service: Using antihistamines during breastfeedingUK governmentSecondaryPage dated 2026-02-05Independent check
- DailyMed: Allegra Allergy (Chattem) OTC Drug FactsDrug company labelTertiaryPage dated 2026-04-14
- Andersson et al., JAMA Pediatrics 2020 (Danish registry cohort)US governmentPrimaryIndependent check
- Andersson et al., JAMA Pediatrics 2020 correction (Figure 1)US governmentPrimaryPage dated 2020-09-01Independent check
- Yamazaki et al., Congenital Anomalies 2026 (Japanese first-trimester cohort)US governmentPrimaryIndependent check
- Yamazaki et al., Congenital Anomalies 2026 corrigendumUS governmentPrimaryPage dated 2026-05-12Independent check
- Lucas et al., Clinical Pharmacology and Therapeutics 1995 (terfenadine milk pharmacokinetics)US governmentPrimaryIndependent check
- Ito et al., American Journal of Obstetrics and Gynecology 1993 (breastfed infant follow-up)US governmentPrimaryIndependent check
- EMA PRAC: Fexofenadine scientific conclusions and product-information variationEU agencySecondaryPage dated 2023-01-04European guidance
Last reviewed 2026-10-16
Independent check 2026-10-16
Not yet clinician-reviewed
Ask your provider about your situation.