Before Using This Medicine

In deciding to use a medicine, the risks of using the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For acyclovir, the following should be considered:

Allergies—Tell your doctor if you have ever had any unusual or allergic reaction to acyclovir. Also tell your health care professional if you are allergic to any other substances, such as preservatives or dyes.

Pregnancy—Topical acyclovir has not been studied in pregnant women. However, this medicine has not been shown to cause birth defects or other problems in animal studies using mice, rats, or rabbits, except when given in very high doses in a study using rats.

Breast-feeding—It is not known whether topical acyclovir passes into the breast milk. However, acyclovir ointment has not been reported to cause problems in nursing babies, even though small amounts of topical acyclovir are absorbed through the mother's skin and mucous membranes. Although most medicines pass into breast milk in small amounts, many of them may be used safely while breast-feeding. Mothers who are taking this medicine and who wish to breast-feed should discuss this with their doctor, especially when lesions are present on or near the breast.

Children—Studies on this medicine have been done only in adult patients, and there is no specific information comparing use of topical acyclovir in children with use in other age groups.

Older adults—Many medicines have not been studied specifically in older people. Therefore, it may not be known whether they work exactly the same way they do in younger adults. Although there is no specific information comparing the use of topical acyclovir in the elderly with use in other age groups, this medicine is not expected to cause different side effects or problems in older people than it does in younger adults.

Other medicines—Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. Tell your health care professional if you are using any other topical prescription or nonprescription (over-the-counter [OTC]) medicine that is to be applied to the same area of the skin.

Other medical problems—Tell your doctor if your herpes simplex infection keeps coming back while you are using acyclovir.