"Guaifenesin" is the active ingredient in many cough medicines, such as Robitussin. It is safe to use in pregnancy.
If a pregnant woman has a severe cough that doesn't respond to guaifenesin, her doctor can prescribe codeine and other narcotics. Some prescription cough syrups combine these ingredients.
Your question raises two important points:
1. A pregnant woman needs to be sure that her cough is not from a more serious problem, such as asthma or pneumonia.
A pregnant woman should call her doctor or midwife if:
- She has other symptoms, such as fever, very bloody sputum or shortness of breath
- Her cough lasts for days in spite of using medications
2. Information about the safety of medications in pregnancy is often limited.
Pregnant women and those caring for them often have to balance uncertainty (a drug seems safe although a small risk cannot be excluded) against the benefit the drug can bring.