For patients · Medication guide

Cyclophosphamide

CYC, Cytoxan

Are you a clinician? See the clinical version of this page.

The short versionCyclophosphamide is a strong immune-suppressing medicine kept for the most serious lupus problems, such as lupus that threatens an organ or severe kidney lupus. It is given as a drip into a vein for a set course.
How you take it

Given as a drip into a vein (or sometimes tablets) for severe, organ-threatening disease. You will be given plenty of fluid and sometimes a bladder-protecting medicine, because it can irritate the bladder. It can affect fertility, so ask about preserving eggs or sperm before starting.

Tests while you take it

You will have regular blood tests and urine checks. Drink plenty of fluid and empty your bladder often on treatment days. Report blood in the urine or signs of infection.

What to know

How it is used in lupus

Because it is powerful, cyclophosphamide is saved for severe lupus, including serious kidney lupus and lupus that threatens an organ. For kidney lupus a lower-dose course is often preferred to reduce side effects.

Common side effects

The more common effects are nausea, lowered blood counts, a higher chance of infections, hair thinning, and bladder irritation. It can also reduce fertility, which your team will discuss and try to protect against.

Tests and monitoring

You will have blood counts and a kidney test weekly for the first 4 weeks, then monthly. If you could become pregnant, you will have a pregnancy test before every dose. Your urine is checked with infusions and then every 6 months after the course, and if the total dose over time is high, your team checks the urine for bladder cancer.

Important cautions

Cyclophosphamide can harm a pregnancy and can affect fertility, so it is generally avoided in pregnancy and stopped before trying to conceive. Your team can offer fertility-protecting steps, such as a hormone medicine for women or storing sperm for men. Your reviewed pregnancy guidance is on the separate pregnancy page.

+Planning a pregnancy? This medicine has separate, reviewed reproductive-health guidance. See the pregnancy guide for this medicine.
iThis page helps you prepare a conversation with your care team. It does not replace individual medical advice. Always confirm your own plan with your rheumatology team.
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