Cytoxan: What to Expect, Side Effects, and More
Cytoxan is a chemotherapy drug that is used to help treat breast cancer. Cytoxan works by damaging the DNA inside breast cancer cells so they cannot replicate. It’s usually used with other chemo medicines, including in the TC, AC, and CMF chemo protocols.
In advanced-stage breast cancer, it may be used before surgery to shrink large tumors. It also is used after surgery and other treatments. In early-stage breast cancer, Cytoxan chemo is typically used after surgery and other treatments to reduce the risk of breast cancer coming back.
See Cytoxan prescribing information.
How Cytoxan works
Cytoxan is an alkylating agent chemotherapy drug. Alkylating agents stop breast cancer cells from reproducing by weakening or destroying their genetic material. These agents are used to treat many different cancers.
Because alkylating agents like Cytoxan damage DNA, they can also affect the bone marrow, which makes new blood cells.
What to expect during Cytoxan treatment
Cytoxan can be taken daily as a pill or intravenously at the doctor’s office either every week or every month. The treatment may be used for three to six months. Cytoxan is almost always given intravenously.
If you’re prescribed Cytoxan chemo pills, follow the directions closely. Do not crush, split, or chew the pills.
During Cytoxan treatment, you must drink more fluids than you usually would. You need to pass urine often to help avoid certain kidney and bladder side effects of Cytoxan. You should empty your bladder frequently, including during the night, so that Cytoxan doesn’t stay in the urine or bladder for too long. If it does, it could cause irritation.
Taking Cytoxan first thing in the morning may help reduce the risk of bladder problems, but you should follow your doctor's instructions about when to take the medication.
Cytoxan side effects
Like almost all breast cancer medicines, Cytoxan can cause side effects, some of them severe.
The most common Cytoxan chemo side effects are:
irregular periods — this can include temporary cessation (usually resume after medication is completed) or permanent cessation of menstrual periods depending on your age and other factors
increased risk of infection
There are also a few rare side effects of Cytoxan. They include:
redness, swelling, or pain at the injection site
sores in the mouth and on the lips
sudden shortness of breath
Real patient reviews
Members of our community discuss their experiences with Cytoxan in the community forum. Here are some of their comments. Remember, it's important to talk to your doctor about any side effects you're having and ask about ways to manage them.
“I have gone on and off Cytoxan and it has worked every time for me. I had to fight for it this time, but it has shrunk my tumors and is working again. I go back to Cytoxan because I have such bad side effects from so many other medications, and I hate the trial and error that I've gone through.” —M360
“The Cytoxan has sinus headaches/ headaches as a side effect. On Friday they did the drip for 60 mins instead of 30 minutes and it seemed to lessen the effect. It's day five and my head hurts.” —Silia
“With Cytoxan and Epirubicin, I had low white counts nausea, extreme fatigue, and just did not feel good — in bed two days after chemo. Better now, one week post. Still a bit weak with low white counts.” —bestock
Read more in our Cytoxan discussion forum.
Paying for Cytoxan
The cost of Cytoxan may vary. The price you’ll pay depends on your health insurance provider and plan, where you live, and the pharmacy you use.
Note: Your insurance company may require you to get prior authorization before covering Cytoxan.
If you have trouble paying for Cytoxan, ask your pharmacist or care team about financial assistance programs that may be able to help.
Learn more about financial assistance and medicine cost-lowering tips.
— Last updated on March 29, 2025 at 3:15 PM