Cyclophosphamide (Cytoxan)

Cyclophosphamide (Cytoxan) is a medicine given through the vein or orally that can decrease the function of the immune system. Cyclophosphamide is used for severe complications of systemic lupus erythematosus (SLE), systemic sclerosis (scleroderma), some forms of vasculitis, myopathies, such as polymyositis and dermatomyositis, and sometimes rheumatoid arthritis.

How to Take It

Cyclophosphamide is often used for three–six months to treat a condition and put it into remission. Afterwards, a medication that may be less potent with fewer side effects is used to maintain the disease in remission. In some cases, cyclophosphamide can be used as a maintenance therapy for certain conditions.

Cyclophosphamide can be taken orally daily or can be given in a liquid form through a needle into a vein every week to every month. The dosing of cyclophosphamide depends on the condition being treated. The oral form is given daily, and the liquid form given as a fixed dose or based on body weight and kidney function generally every 2–4 weeks.

Side Effects

Common side effects, which may be worse with the pill form, include nausea and vomiting. These symptoms usually can be controlled with anti-nausea medications. Hair loss can occur, but hair usually will grow back when the medication is stopped. Other common side effects include skin rashes. It can also increase the risk of infections. Cyclophosphamide may decrease white blood cells. This can occur 8–12 days after starting treatment. Your doctor will check your blood counts around this time and make dose adjustments as needed.

Cyclophosphamide can also cause infertility in both men and women. Although women taking cyclophosphamide can stop having periods, they can still become pregnant, so an effective form of birth control to prevent pregnancy because the medicine is not safe for a developing baby.

Cyclophosphamide may also cause blood in the urine or scarring of the bladder. Patients taking oral cyclophosphamide should drink plenty of fluids each day to help with bladder problems. A medication called mesna may help prevent bladder problems. Cyclophosphamide also increases the risk of developing some kinds of cancer, including lymphoma, skin, and bladder cancer.

Tell Your Rheumatology Provider

Before starting, let your rheumatology provider know all medications you are taking, including over-the-counter medicines and herbal supplements. Notify your other physicians when taking this drug or have been given this in the past. There are some long-term risks to be considered even years after taking the medication.

Live vaccines should be avoided while on this medication, and caution should be taken if any household members receive live vaccines. You should discuss updating your vaccinations prior to starting this medication. Women who are pregnant or considering becoming pregnant should talk with their doctor before taking this drug. You should contact your rheumatology provider if you notice the following: blood in your urine, fevers and chills, easy bruising or bleeding, shortness of breath, and/or swelling of the feet and ankles.

Updated February 2024 by Mohammad Ursani, MD, and reviewed by the American College of Rheumatology Committee on Communications and Marketing.

This information is provided for general education only. Individuals should consult a qualified health care provider for professional medical advice, diagnosis, and treatment of a medical or health condition.