Before using ganciclovir, tell your doctor or pharmacist if you are allergic to it; or to valganciclovir or acyclovir; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.

Before using this medication, tell your doctor or pharmacist your medical history, especially of: kidney problems, a low number of blood cells (red or white blood cells, platelets), radiation treatment.

This drug may make you dizzy or drowsy or make it harder for you to think clearly. Alcohol or marijuana (cannabis) can worsen these effects. Do not drive, use machinery, or do anything that needs alertness until you can do it safely. Limit alcoholic beverages. Talk to your doctor if you are using marijuana (cannabis).

Ganciclovir can make you more likely to get infections or may make current infections worse. Stay away from anyone who has an infection that may easily spread (such as chickenpox, COVID-19, measles, flu). Talk to your doctor if you have been exposed to an infection or for more details.

Tell your health care professional that you are using ganciclovir before having any immunizations/vaccinations. Avoid contact with people who have recently received live vaccines (such as flu vaccine inhaled through the nose).

To lower the chance of getting cut, bruised, or injured, use caution with sharp objects like razors and nail cutters, and avoid activities such as contact sports.

Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).

Older adults may be at greater risk for kidney problems while using this drug.

Women who are pregnant or who may become pregnant should not handle this medication.

During pregnancy, this medication should be used only when clearly needed. It may harm an unborn baby. Discuss the risks and benefits with your doctor. Women of childbearing age should have a pregnancy test before starting this medication. To prevent pregnancy, men with female partners should always use effective barrier protection (such as latex or polyurethane condoms) during all sexual activity during treatment and for at least 90 days after stopping the medication. Women of childbearing age who are using ganciclovir should use reliable forms of birth control (such as birth control pills and condoms) during treatment and for at least 30 days after stopping the medication. Consult your doctor for more details.

It is unknown if this medication passes into breast milk. Because of the possible risk to the infant, breastfeeding is not recommended while using this medication. Consult your doctor before breastfeeding.