Read the Patient Information Leaflet if available from your pharmacist before you start taking letermovir and each time you get a refill. If you have any questions, ask your doctor or pharmacist.

Take this medication by mouth with or without food, as directed by your doctor, usually once daily. The dosage is based on your medical condition, response to treatment, and other medications you may be taking. Children's dosage is also based on weight. Be sure to tell your doctor and pharmacist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).

Swallow the tablet whole. Do not crush or chew because the drug has a bitter taste.

For the best effect, take this medication at evenly spaced times. To help you remember, take this medication at the same time every day.

Continue to take this medication until the full prescribed amount is finished. Stopping the medication too early may result in an infection.