Which antibiotics are safe during pregnancy?
Each and every antibiotic is made with different ingredients and will have different effects on mom and baby. Read through to find out about the antibiotic you have been prescribed:
- Aminoglycosides: Examples of this class of drug include gentamycin (the aminoglycoside most commonly prescribed during pregnancy), tobramycin, and streptomycin. Known side effects in those taking the drug include kidney and hearing injury. However, gentamycin has not been shown to cause birth defects, or damage kidneys or hearing in the fetus.
- Bactrim: This is actually a combination of a sulfamethoxazole, a sulfonamide, and trimethoprim, a drug belonging to another antibiotic class. Among its many uses, Bactrim is frequently prescribed for urinary tract and respiratory tract infections. Sulfonamides should not be used during the last trimester of pregnancy, or during nursing, because they can produce jaundice in the newborn.
- Biaxin: This drug appears to have adversely affected pregnancy outcome in some animal studies, but it has no known detrimental effects on human pregnancies. Biaxin is listed as FDA category C.
- Cephalosporins: These antibiotics (ex: Keflex) are usually in category B and safe to take in pregnancy.
- Clindamycin (Cleocin): This is an FDA category B drug, and is indicated for a number of infections during pregnancy, including certain pelvic infections. It is also used to treat postpartum uterine infections. Clindamycin is not known to cause fetal harm.
- Erythromycin: This is considered to be safe for use during pregnancy. It does not readily cross the placenta, which is actually a disadvantage for infections in which the fetus should also be treated. Both azithromycin and clarithromycin have a broader spectrum of activity and fewer gastrointestinal side effects than erythromycin. Both erythromycin and azithromycin are FDA category B drugs.
- Ethambutol: THis drug is not known to produce adverse effects on the human fetus, although data is limited, and the drug's effects when it is used in combination with other tuberculosis drugs is not known. Incidentally, streptomycin, another antituberculous agent, should not be used during pregnancy, since it can cause adverse fetal effects. Other antituberculous drugs should also be avoided because their effects on the fetus have not been adequately evaluated.
- Floroquinolones: This class of antimicrobials includes drugs such as ciprofloxacin (Cipro), norfloxacin (Noroxin), and ofloxacin (Floxin). They are FDA category C, and should be avoided during pregnancy and breastfeeding because of concerns about possible detrimental effects on cartilage and joint development in the developing fetus and infant.
- Gentamycin: This is an FDA category C drug, and may be used when its benefits outweigh the risks of its use. Examples of such situations include certain pelvic, heart valve, or kidney infections.
Isoniazid has not been shown to cause birth defects or other fetal harm in humans. Neither has its use been demonstrated to cause birth defects in animal studies, although the drug may cause embryo death in rats and rabbits and can cause lung cancer in specific strains of mice. It is FDA category C. When INH is prescribed during pregnancy, pyridoxine (Vitamin B6) should be taken concurrently.
- Macrolides: This class of antimicrobials includes erythromycin, azithromycin (Zithromax), and clarithromycin (Biaxin).
- Metronidazole (Flagyl): This is used to treat trichomonas vaginalis infections, which can be the cause of significant vaginal irritation. It has not been demonstrated to be harmful to human fetuses. Metronidazole does cause cancer in rodent studies. However, this effect has not been demonstrated in other animal models. The drug should not be prescribed during the first trimester of pregnancy, and should only be used if clearly needed. It is FDA category B. Antituberculous Drugs Recommendations for the initial treatment of tuberculosis in pregnant women include the drugs isoniazid (INH) and rifampin. If resistance to INH seems likely, ethambutol should also be added.
- Nitrofurantoin (Macrobid, Macrodantin): This drug is mainly used during pregnancy to treat urinary tract infections. It has not been shown to cause harmful effects on the human fetus, nor has it caused adverse effects on the fetus in animal studies. However, the drug's safety in pregnant women has not been established. Moreover, nitrofurantoin should not be used in women at term. It is an FDA category B drug.
- Penicillin: Most penicillins (eg Ampicillin) are in the FDA pregnancy category A or B. This means that it is unlikely to harm an unborn baby.
- Rifampin: This causes birth defects in rodents. Its effect on the human fetus, either alone or in combination with other antituberculous drugs, is unknown. Rifampin is also FDA category C.
- Spectinomycin: This drug is related to the aminoglycoside antibiotics. It is FDA category B, and is not known to cause fetal harm. It can be an effective alternative for the treatment of gonorrhea infections in pregnant women who are allergic to penicillin and cephalosporin drugs.
- Streptomycin: This drug is used to treat tuberculosis, is a category D drug and should not be given during pregnancy unless it is absolutely necessary.
- Tetracyclines: Tetracyclines are FDA drug category D, and should not be used during pregnancy unless no other alternatives are available. Tetracyclines cross the placenta, and will deposit in fetal teeth causing discoloration if they are given after the fifth month of pregnancy. Tetracylines may also cause other, more serious, birth abnormalities. Some representative examples of tetracylines are tetracycline, doxycycline (Vibramycin), and minocycline (Minocin). Tetracyline use has been associated with liver damage in pregnant women.
- Sulfonamides: These drugs are the oldest class of antibiotics. The best known sulfonamide is trimethoprim-sulfamethoxazole. It is marketed under the trade names Bactrim and Septra.
Trimethoprim interferes with folate metabolism, at least in bacteria. The sulfonamides are FDA category B drugs, while trimethoprim and Bactrim are listed as FDA category C medications.
- Vancomycin: Although Vancomycin is an FDA category C drug, it has several clearly defined uses in pregnancy. Among these are infections caused by Staphylococcus Aureus bacteria, commonly known as "staph infections," that are resistant to other drugs, certain heart valve infections, and intestinal infections with toxic strains of the bacterium Clostridium Difficile. Vancomycin is typically administered intravenously since its oral absorption is poor, but when the antibiotic is used to treat intestinal infections, it is taken by mouth. Vancomycin can cause hearing and kidney damage in recipients of the drug, but is not known to cause fetal harm.