Diarrhoea on sacituzumab govitecan and how it is managed

Loose motions, or diarrhoea, are one of the two most important side effects of sacituzumab govitecan, alongside a low white cell count. The chemotherapy part of the medicine, SN-38, is the same active substance that forms in the body from irinotecan, a chemotherapy drug well known for affecting the bowel. It irritates the lining of the gut, so the bowel absorbs less water. In studies, more than half of people had some loose motions, and a smaller group had severe episodes. There are two patterns. Early loose motions can come on during the drip or within a day, often with stomach cramps, sweating, watery eyes, a runny nose or extra saliva. This is caused by the drug stimulating certain nerves, and it is usually treated with an injection of atropine, which may then be given before later doses. Late loose motions start days after the dose and are the more common type. They are managed by starting anti-diarrhoea tablets, usually loperamide, as soon as they begin, drinking plenty of fluids and adjusting what you eat. The medicine label advises that infections should be ruled out and that doses are held for severe episodes until they settle. Acting on the first loose stool, rather than waiting, is the single most useful thing you can do.

Start treatment early

Begin the tablets at the first loose stool, exactly as your team explained.

Replace fluids

Oral rehydration solution replaces both water and salts lost with loose motions.

Know when to call

Loose motions that continue despite tablets, or come with fever or dizziness, need same-day advice.

For most people, loose motions are manageable. For a few, they become severe enough to need hospital care, which is why the early warning signs matter.

It can happen with any cycle

Not having loose motions in the first cycle does not mean they will never appear.

Doses may need adjusting

After a severe episode, the next dose is usually held until you recover and may be lowered.

Some people are more at risk

People with a slower UGT1A1 enzyme, bowel disease or earlier bowel surgery may be more affected.

What this page cannot tell you

It cannot replace your team's written plan, which may use different doses or timings from those described here.

A little preparation before every dose makes it easier to act quickly if loose motions begin.

Stock up

Keep your anti-diarrhoea tablets and some oral rehydration sachets at home, and check they have not run out.

Know your written plan

Ask how many tablets to take, how often, and the most you can take in a day, and write it down.

Tell the team at every visit

Mention how your bowels were after the last dose, even if things settled on their own. It helps the team decide whether to add medicine or adjust the dose.