Is It Safe to Use Acyclovir in Pregnancy?

The risk of using medications such as acyclovir in pregnancy must be balanced against the risk to the baby and mother from the condition that requires treatment. Acyclovir is an antiviral medicine that can control outbreaks of herpes viruses, including those that cause cold sores. It can be administered as a skin ointment, as an injection, or as an oral medication. Although, as of 2011, acyclovir is not definitively associated with harm to unborn children, a doctor's approval should be sought prior to using the drug.

Acyclovir is active on certain viruses and treats the sores that can result from infections. The drug is not a cure and merely reduces symptoms. Examples of these viruses include the cold sore virus, chicken pox, and genital herpes. A feature of the infections that the drug treats is that they can all recur over periods of time, like shingles that may flare up in adulthood from childhood chicken pox. Some of these conditions are mild enough to be merely troublesome, such as a cold sore, and a woman may be able to avoid acyclovir in pregnancy for these issues.

Drugs in pregnancy are usually only prescribed in limited circumstances. Human safety trials are generally conducted prior to a drug being released for use, but these trials rarely include pregnant women. Therefore, the safety of drugs on a pregnant woman and her fetus needs to be judged by animal studies.

Even if the animal studies show no harm to the baby or to the woman, this does not necessarily mean that the pregnancy is unaffected in humans. For this reason, drugs are usually tightly controlled in pregnancy. As of 2011, use of acyclovir in pregnancy has not been banned by the U.S. Food and Drug Administration, but little evidence is available to prove, on the other hand, that the drug is safe during pregnancy.

Sometimes, however, the condition caused by the virus is more serious than a cold sore. Herpes is one such example, where the herpetic lesions on the genital regions may adversely affect the health of the baby. The disease may also endanger the life of the mother as potentially lethal conditions such as lung disease, liver problems, or encephalitis can be caused by the herpes virus. In cases like these, acyclovir in pregnancy may be the best option for mother and child despite the theoretical risks to the baby from the drug. A doctor's approval is necessary prior to using the drug, as he or she can balance the risk to the baby and the mother from an infection against the potential risk from the drug.

Injections of acyclovir send the drug directly into the mother's bloodstream, whereas oral capsules or tablets are absorbed through the gastrointestinal tract. Topical ointments may also be absorbed through the skin. All of these forms of drug delivery have the potential to reach the fetus during pregnancy. The drug may also make its way into breast milk, so breast-feeding mothers should also seek a doctor's advice before using the medication.