Oncura

FOLFIRI + Cetuximab: what to expect, day by day

Colorectal14-day cycle5 effects documented

FOLFIRI plus the targeted antibody cetuximab. On top of FOLFIRI's diarrhea and low counts, expect an acne-like rash on the face and upper body within the first couple of weeks.

FOLFIRI (every 2 weeks) plus the antibody cetuximab. Cetuximab adds a distinctive acne-like rash that appears in the first 1-2 weeks, plus low magnesium. Only used for RAS wild-type tumors.

Get help straight away — this is true on any regimen, on any day.

A temperature of 100.4°F (38°C) or higher during treatment can mean a serious infection while your blood counts are low. Call your team or go to the ER — do not wait it out.

Also urgent: trouble breathing or chest pain · swelling of the face, lips or throat · new confusion or fainting · shaking chills · not being able to keep fluids down.

This is standing guidance shown to everyone. Nothing on this page is based on anything about you, and nobody is monitoring you.

Timed to the cycle

Day 1 is the day of your infusion. These are the effects a retrievable document ties to a day range for this regimen — not a prediction about you.

Infusion reaction

During or just after an infusion

A reaction during the first infusion (fever, chills, flushing, rarely trouble breathing). You'll get pre-medication and be watched closely; most reactions are mild.

Call your team urgently: Any trouble breathing, throat tightness, or dizziness during the infusion — tell staff at once.

reported by about 15-20% of people; severe in 2-5% · Timing is part of what this effect is · from Cetuximab

Late-onset diarrhea

Typically around days 5–11

Diarrhea (often from about day 5) that can be worsened by the combination. Start loperamide at the first loose stool and hydrate; call your team if it escalates.

Call your team urgently: More than 6 stools above normal, diarrhea with fever, or any with lightheadedness — call urgently.

reported by about ~65% of people; severe in 15-16% · Timing from the manufacturer’s prescribing information · from Irinotecan, Cetuximab

Neutropenia

Typically around days 8–27

A temporary drop in infection-fighting white cells.

Call your team urgently: A temperature of 100.4°F (38.0°C) or higher — an emergency.

reported by about ~50% of people; severe in 24-31% · Timing from a drug-monograph reference · from Irinotecan, Fluorouracil

Not tied to a cycle day

These build with the number of doses, or are measured from when treatment started, so a cycle day would be the wrong shape for them. Each keeps the timing its own source states.

Acneiform rash

first 1-2 weeks

An acne-like rash on the face, scalp, chest, and back — a sign the drug is working on skin cells. It usually appears in the first 1-2 weeks. Gentle skin care, sun protection, and sometimes antibiotics/creams help; tell your team early.

Call your team: Rash with widespread blistering, peeling, or signs of skin infection (pus, spreading redness).

reported by about 86% of people; severe in 18% · from Cetuximab

Low magnesium (hypomagnesemia)

builds over weeks of treatment

Cetuximab can make the kidneys waste magnesium. Low levels can cause cramps, tiredness, or tingling. Your team checks bloodwork and may give magnesium replacement.

reported by about ~30% of people; severe in 5-6% · from Cetuximab

Where this comes from

  1. S1. Van Cutsem E, CRYSTAL trial (FOLFIRI ± cetuximab) (2009) — PMID 19339720
  2. S2. Cetuximab (Erbitux) FDA prescribing information — FDA label
  3. S3. Irinotecan (Camptosar) FDA prescribing information — FDA label

Timing windows on this page rest on:

A window appears here only where a retrievable document ties it to a drug in this regimen. Where nothing could be found, the window was removed rather than estimated — so a missing time is an honest gap, not an oversight.

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