Azithromycin (Zithromax) and Cough Medications in Pregnancy at 18 Weeks
Azithromycin is safe to use at 18 weeks gestation, and both dextromethorphan and guaifenesin are also considered safe during pregnancy.
Azithromycin (Zithromax) Safety
Azithromycin is classified as FDA Pregnancy Category B and can be used safely throughout pregnancy, including at 18 weeks gestation. 1
Evidence Supporting Safety:
The FDA label explicitly states that available data from published literature and postmarketing experience over several decades with azithromycin use in pregnant women have not identified any drug-associated risks for major birth defects, miscarriage, or adverse maternal or fetal outcomes. 2
Animal studies showed no drug-induced fetal malformations at doses up to 4 times (rats), 2 times (mice), and 2 times (rabbits) the adult human daily dose. 2
A controlled human study of 184 pregnant women (128 used azithromycin in the first trimester) found no statistically significant increase in major malformations compared to controls: 3.4% in the azithromycin group versus 2.3% in disease-matched controls and 3.4% in non-teratogen controls. 3
The 2025 EULAR guidelines for antirheumatic drugs in pregnancy do not list azithromycin as contraindicated or requiring special precautions during pregnancy. 4
Clinical Context:
Azithromycin is widely used during pregnancy for respiratory infections, sexually transmitted diseases, and even as prophylaxis during labor. 5, 6
The European Respiratory Society/Thoracic Society of Australia and New Zealand guidelines classify azithromycin as "probably safe" during pregnancy (Category B1). 7
At 18 weeks gestation, you are well past the critical period of organogenesis (first trimester), further reducing any theoretical concerns. 2
Dextromethorphan Safety
Dextromethorphan is safe for use during pregnancy at 18 weeks gestation. 8, 9
A controlled study of 184 pregnant women (128 used dextromethorphan in the first trimester) found no increase in major malformations above baseline: 2.3% in the dextromethorphan group versus 2.8% in controls. 9
The study specifically concluded that dextromethorphan use during pregnancy does not increase the rates of major malformations above the expected baseline rate of 1-3%. 9
Dextromethorphan is commonly used for symptomatic relief of cough in pregnant women with acute bronchitis. 8
A large epidemiological study found that dextromethorphan was used by a significant proportion of pregnant women, with usage actually increasing during pregnancy compared to before pregnancy. 10
Guaifenesin Safety
Guaifenesin is safe for use during pregnancy at 18 weeks gestation. 8, 10
Guaifenesin is recommended as an expectorant for symptomatic relief in pregnant women with acute bronchitis. 8
The same large epidemiological study that examined dextromethorphan found that guaifenesin use was higher during pregnancy than before pregnancy, suggesting it is commonly used and considered safe by healthcare providers. 10
No specific teratogenic concerns have been identified with guaifenesin use during pregnancy. 8
Important Caveats:
While azithromycin is safe, it should only be used when there is a clear bacterial indication (such as bacterial pneumonia, pertussis, or other documented bacterial infections), not for viral upper respiratory infections. 8
For simple acute bronchitis (which is usually viral), antibiotics including azithromycin are not routinely recommended unless pneumonia is suspected. 8
The most common side effects of azithromycin are gastrointestinal (nausea, vomiting, abdominal pain, diarrhea), which may be more bothersome during pregnancy. 1
Over-the-counter cough medications (dextromethorphan and guaifenesin) have a low incidence of minor adverse effects including nausea, vomiting, headache, and drowsiness. 8