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Lomustine

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Why has my veterinarian prescribed this medicine?

Lomustine is used to treat lymphoma and tumors of the central nervous system in dogs and cats.  It may be used to treat other forms of cancer as well.

How do I give this medication?medications

"The person administering the drug should wear gloves or at a minimum wash their hands after handling the medication."
  • Give this medication to your pet as directed by your veterinarian. READ THE LABEL CAREFULLY.
  • Give this medication on an empty stomach, if possible.
  • Depending on the condition being treated, this medication is given once every 3 to 8 weeks.
  • Your pet may require blood work before the next dose of medication is given.
  • DO NOT give the pet more medicine than directed and do not give more often than directed.
  • Try not to miss giving any doses.
  • The person administering the drug should wash their hands after handling the medication.

What if I miss giving a dose?

Contact your veterinarian if you have missed giving a dose.

How do I store this medicine?

  • Keep this medicine out of reach of children.
  • Store this medicine in a cool, dry place at room temperature. Store away from heat and direct sunlight.
  • Do not store this medicine in the bathroom, near the kitchen sink or in damp places. The medicine may break down if exposed to heat or moisture.

What are the potential side effects?

  • Your pet may experience the following side effects: a loss of appetite, vomiting, diarrhea, mouth sores, loss of hair, changes to the cornea. Rarely, liver and kidney toxicity may occur.
  • The most serious side effects result from bone marrow depression (anemia, thrombocytopenia, leucopenia and hepatotoxicity).
  • Other side effects may occur. If you notice anything unusual, contact your veterinarian.

Are there any possible drug interactions?

  • Make sure to tell your veterinarian what other medication you are giving to your pet.
  • Quite often, your veterinarian may prescribe two different medications, and sometimes a drug interaction may be anticipated. In this case, your veterinarian may vary the dose and/or monitor your pet more closely.
  • The following drugs can potentially interact with lomustine: other antineoplastic medications, other bone marrow depressants, immunosuppressant drugs, live virus vaccines.
  • Contact your veterinarian if your pet experiences any unusual reactions when different medications are given together.

© Copyright 2025 LifeLearn Inc. Used and/or modified with permission under license. This content written by LifeLearn Animal Health (LifeLearn Inc.) is licensed to this practice for the personal use of our clients. Any copying, printing or further distribution is prohibited without the express written consent of LifeLearn. This content does not contain all available information for any referenced medications and has not been reviewed by the FDA Center for Veterinary Medicine, or Health Canada Veterinary Drugs Directorate. This content may help answer commonly asked questions, but is not a substitute for medical advice, or a proper consultation and/or clinical examination of your pet by a veterinarian. Please contact your veterinarian if you have any questions or concerns about your pet’s health. Last updated on Feb 12, 2014.