FOLFIRI: what to expect

Cliff notes

Drugs in it: Irinotecan, 5-FU (fluorouracil), plus leucovorin.

Typical schedule: Usually every 2 weeks: irinotecan and leucovorin by IV, a 5-FU push, then a 46-hour 5-FU pump at home. Sometimes combined with Avastin or another targeted drug.

What to expect: Diarrhea is the side effect to watch most closely. Hair loss, low blood counts and tiredness are also common. 5-FU's FDA label now recommends a DPYD gene test before starting.

Your exact schedule and number of cycles are set by your oncologist and may differ from what's described here.

Side effects to know

📅 Sample 14-day cycle

= 💉 clinic day 1, home pump to day 3. Repeats every 2 weeks. This is an example; follow the schedule your team gives you.

Call your care team now if you have:

Fever of 100.4°F (38°C) or higher, or chills (possible infection when blood counts are low)
Vomiting or diarrhea that won't stop, or you can't keep fluids down
Unusual bleeding or bruising
Shortness of breath or chest pain
Signs of an allergic reaction during or after an infusion: trouble breathing, swelling of the face or throat, hives

Call 911 for trouble breathing, chest pain or signs of stroke.

▶ Watch

Watch: How to Prepare for Your First Infusion Treatment (Chemotherapy, Immunotherapy or Targeted Therapy) (Fred Hutch Patient Education)

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❓ Questions to ask your doctor

What is the goal of this treatment for me?
How will we know if it's working?
Which side effects should I call about right away, and what number do I call after hours?
Which medicines, vitamins or supplements should I avoid?
Will this affect my ability to work, drive or care for my family?
What will this cost me, and who can help me with coverage?
How many cycles will I get, and what happens after?

Help paying

See each drug page for programs, or the independent foundations. Infused chemo is usually covered by Medicare Part B; see Medicare and your cancer drugs.

PAN Foundation: Copays and coinsurance, including for people with Medicare, when a disease fund is open.
HealthWell Foundation: Grants for copays, deductibles and premiums when a fund is open.
CancerCare Co-Payment Assistance Foundation: Help with treatment copays for insured people under income limits.
Good Days: Copay help and some travel costs.
NeedyMeds: Free database of assistance programs, open to anyone.

Common questions

Is FOLFIRI harder than FOLFOX?

They have different side effects rather than one being 'harder'. FOLFIRI more often causes diarrhea and hair loss; FOLFOX more often causes neuropathy.

Written by the Cancer Side Effects Guide team from FDA labels and leading cancer centers. Not medical advice. · Last updated: October 15, 2026 · How we write

Not medical advice. This page is general information to help you talk with your care team. It can't replace advice from your doctor or nurse. If you have a fever of 100.4°F (38°C) or higher during treatment, or any symptom that worries you, call your care team now. In an emergency, call 911.