When you start chemotherapy for stomach or colorectal cancer, your head fills with worries before the medicine ever goes in. "What if I throw up?" "Will I even be able to eat?" "Can I keep going to work?" The questions pile up one after another. The truth is that side effects vary enormously from person to person and from drug to drug, so the scary story you heard from someone else will not necessarily play out the same way for you. Still, having the big picture in advance means you panic less when symptoms actually show up.
The most common thing people deal with is nausea and vomiting. These days the anti-nausea medicine given before the chemo infusion has gotten quite good, so severe vomiting is far less common than it used to be. The key is not to reach for the medicine after symptoms hit, but to take it ahead of time exactly as your care team has prescribed. When your appetite drops off a cliff, do not force down a big meal at once. Soft foods like rice porridge or thin gruel, eaten in small amounts and spread out over the day, go down much easier. If you have also had surgery on your stomach or intestines, cutting the size of each meal and eating more often becomes the basic rule. Many people find that cold food smells less and turns the stomach less, so trying cooled dishes instead of hot soup is worth a shot.
Diarrhea and constipation are always part of the picture with gastrointestinal chemotherapy too. Frequent diarrhea in particular can dehydrate you fast, draining your energy and leaving you dizzy. Drink water often, and if loose stools keep coming several times a day or you run a fever along with it, that is not something to tough out, it is a reason to call the hospital right away. The opposite, not passing stool for several days or feeling bloated and tight in the belly, should not be left alone either. With either one, putting it off with "this is probably fine" lands people in the emergency room more often than you would think.
The next thing to watch is your immune system. Chemotherapy drugs do not single out only cancer cells; they knock down normal cells like white blood cells along the way. So about a week to ten days after the infusion, you become especially vulnerable to infection. Washing your hands often, steering clear of crowded places, and choosing cooked food over anything raw matter a lot during this window. If you spike a fever over 38C, this is not the time to take a cold tablet and ride it out; you need to call right away. A fever while your white blood cell count is low is no big deal if it is dealt with quickly, but it can turn dangerous if you wait, which is why care teams hammer this point home until they are blue in the face.
Meanwhile, everyday life keeps rolling along. When nerve symptoms like tingling or pins and needles in the hands and feet, hair loss, and a fatigue that wears you out easily all pile up at once, it is easy for your spirits to sink. Fatigue does not necessarily lift just by lying down all the time; many people find that moving the body a little, a light walk on the days you feel up to it, actually helps more. Rather than dropping work entirely, it is common to find a middle ground by dialing down the intensity or adjusting around your treatment cycle. And do not suffer in silence. Even a rough symptom diary means that at your appointment you will not be fumbling over "when did that start again," and you can report things accurately, which makes adjusting your medication far smoother.
What is written here is only the broad outline; in the end, the answer that fits your body is best known by the care team that sees you in person. Jot down any symptom that feels off and be sure to ask about it.
Disclaimer: This article is for general information only and is not a substitute for professional medical diagnosis or treatment. Always consult your doctor or care team about your own condition and any symptoms you experience.