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Cyclophosphamide

Prescription
Alkylating agent — antineoplastic / Immunosuppressant
Last reviewed 19 Apr 2026 · PetCare.AI Editorial Team
Species
Dog, Cat
Brands
3 available
Interactions
3 documented
Formulations
3

Mechanism of action

Prodrug metabolized by hepatic P450 to active phosphoramide mustard, which cross-links DNA; also immunosuppressive via lymphocyte depletion

At a glance

Class
Alkylating agent — antineoplastic / Immunosuppressant
Schedule
Prescription
Storage
Store below 25°C; handle with gloves (cytotoxic); reconstituted solution stable 24h at room temp

Dosing

🐕

Dog

Lymphoma (CHOP protocol) / IMHA / Immune-mediated disease
Dose
200–300 mg/m²
Route
PO, IV
Frequency
Every 2–3 weeks (oncology); daily low-dose for immunosuppression
Max dose
500 mg
Duration: Per protocol; typically 4–6 cycles for lymphoma
🐈

Cat

Lymphoma / Immune-mediated disease
Dose
200–300 mg/m²
Route
PO, IV
Frequency
Every 2–3 weeks
Max dose
200 mg
Duration: Per oncology protocol

Formulations

💊

Tablet — 1

Strength
50mg
Available in India
💉

Injection — 2

Strength
200mg vial
Available in India
Strength
500mg vial
Available in India

Storage

Store below 25°C; handle with gloves (cytotoxic); reconstituted solution stable 24h at room temp

Safety

Absolute contraindications — do not use

  • Severe bone marrow suppression
  • Active urinary tract infection
    Sterile hemorrhagic cystitis risk

Adverse effects

Common
Myelosuppression (nadir 7–14 days)
GI upset
Alopecia
Serious
Sterile hemorrhagic cystitis
Severe neutropenia/sepsis
Cardiotoxicity (rare)

Monitoring parameters

CBC (day 7 and 14 post-dose)UrinalysisEncourage frequent urination (furosemide co-administration for cystitis prevention)

Interactions

Major — 3

Furosemide
major
Furosemide inhibits renal excretion of cyclophosphamide metabolites, increasing risk of hemorrhagic cystitis
Management: Avoid concurrent use. Ensure adequate hydration and frequent voiding during cyclophosphamide therapy.
Doxorubicin
major
Both are cardiotoxic; combined use increases risk of cumulative cardiomyopathy
Management: Monitor cardiac function with echocardiography. Limit cumulative doxorubicin dose to 180-240 mg/m² in dogs.
Chloramphenicol
major
Chloramphenicol inhibits hepatic CYP enzymes required to activate cyclophosphamide prodrug, reducing its antineoplastic efficacy.
Management: Avoid concurrent use. Use alternative antibiotic during cyclophosphamide chemotherapy.

Brands

International

Cytoxan
Baxter

India

Endoxan
Baxter India
Cycloxan
Cadila

FAQs

Frequently asked questions

›What is Cyclophosphamide?
Cyclophosphamide is a alkylating agent — antineoplastic / immunosuppressant used in pets. Prodrug metabolized by hepatic P450 to active phosphoramide mustard, which cross-links DNA; also immunosuppressive via lymphocyte depletion
›What is Cyclophosphamide used for in pets?
Cyclophosphamide is used in veterinary medicine for: Lymphoma (CHOP protocol) / IMHA / Immune-mediated disease; Lymphoma / Immune-mediated disease.
›What is the Cyclophosphamide dose for dogs?
For dogs, Cyclophosphamide is typically dosed as follows — Lymphoma (CHOP protocol) / IMHA / Immune-mediated disease: 200–300 mg/m² PO/IV Every 2–3 weeks (oncology); daily low-dose for immunosuppression. Always consult your veterinarian for a dose tailored to your pet's weight, age, and condition.
›What is the Cyclophosphamide dose for cats?
For cats, Cyclophosphamide is typically dosed as follows — Lymphoma / Immune-mediated disease: 200–300 mg/m² PO/IV Every 2–3 weeks. Always consult your veterinarian for a dose tailored to your pet's weight, age, and condition.
›What are the side effects of Cyclophosphamide?
Common: Myelosuppression (nadir 7–14 days), GI upset, Alopecia. Serious (call your vet immediately): Sterile hemorrhagic cystitis, Severe neutropenia/sepsis, Cardiotoxicity (rare).
›Does Cyclophosphamide need a prescription?
Yes. Cyclophosphamide is a prescription medication and should only be administered under veterinary supervision.
›When should Cyclophosphamide not be used?
Do not use Cyclophosphamide if: Severe bone marrow suppression; Active urinary tract infection.

References

References

Textbooks & handbooks

  • Plumb, D.C. Plumb's Veterinary Drug Handbook. 10th ed., Wiley-Blackwell, 2023.
  • Vail, D.M., Thamm, D.H., & Liptak, J.M. (eds.). Withrow & MacEwen's Small Animal Clinical Oncology. 6th ed., Saunders/Elsevier, 2020.
  • Riviere, J.E., & Papich, M.G. (eds.). Veterinary Pharmacology and Therapeutics. 10th ed., Wiley-Blackwell, 2018.
  • National Research Council. Nutrient Requirements of Dogs and Cats. National Academies Press, Washington DC, 2006.
  • The Merck Veterinary Manual. Merck & Co., Online edition. https://www.merckvetmanual.com/

Clinical guidelines & consensus

  • Fletcher, D.J., Boller, M., Brainard, B.M., et al. "RECOVER Evidence and Knowledge Gap Analysis on Veterinary CPR." Journal of Veterinary Emergency and Critical Care, 2012;22(S1):S102–S131.
  • American Animal Hospital Association. 2018 AAHA Diabetes Management Guidelines for Dogs and Cats. AAHA Press.

Journals & peer-reviewed studies

  • Hogan, D.F., Fox, P.R., Jacob, K., et al. "Secondary prevention of cardiogenic arterial thromboembolism in the cat: The FAT CAT study." Journal of Veterinary Cardiology, 2015;17(Suppl 1):S306–S317.
  • Boswood, A., Häggström, J., Gordon, S.G., et al. "Effect of Pimobendan in Dogs with Preclinical Myxomatous Mitral Valve Disease and Cardiomegaly: The EPIC Study — A Randomized Clinical Trial." Journal of Veterinary Internal Medicine, 2016;30(6):1765–1779.
  • ASPCA Animal Poison Control Center. Toxicology and Poison Management Guidelines. American Society for the Prevention of Cruelty to Animals. https://www.aspca.org/pet-care/animal-poison-control

Regulatory & approvals

  • Central Drugs Standard Control Organisation (CDSCO), Government of India. Veterinary Drug Approval Registry, 1969–2026. Directorate General of Health Services. https://cdsco.gov.in/

Databases

  • Washington State University, College of Veterinary Medicine. Veterinary Clinical Pharmacology Laboratory (VCPL) — MDR1 Multidrug Sensitivity Database. https://vcpl.vetmed.wsu.edu/
Educational reference only
This information is provided for educational purposes and is not a substitute for professional veterinary advice, diagnosis, or treatment. Always consult a qualified veterinarian before administering any medication to your pet. Find a vet near you →

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