When you're going through chemotherapy for a blood cancer, the scariest thing often isn't the pain itself but the "vague" symptoms. You feel a slight low-grade fever and you can't tell whether you're just tired or whether it's a warning sign. But when your white blood cell count has hit rock bottom, that small difference matters a lot. A touch of a cold that you'd normally shake off with a day of rest can turn serious within a few hours when your neutrophils are low. That's exactly why "let's wait and see a little longer" can be the most dangerous decision you make.
The first number to memorize is 100.4°F (38°C). If your temperature taken by ear or under the arm goes above 38°C, or if 37.5°C (99.5°F) won't come down for more than an hour, call the hospital right away. A fever during chemo isn't treated as a simple cold; it's viewed as an emergency called febrile neutropenia, because it can progress into sepsis, where bacteria spread through the body. It's also not a good idea to take fever medicine you have at home first, since a brief dip in your temperature can mask the real danger. The right order is to write down your temperature and get instructions from your care team first.
Bleeding is another sign you can't just brush off. When chemo lowers your platelets, blood doesn't clot well. If you see blood on your gums when you brush, if a nosebleed won't stop after ten minutes, or if bruises keep appearing here and there even though you haven't bumped into anything, it may mean your platelet count has dropped to a dangerous level. More urgent still is when your urine is red or black, or there's blood in your stool, or your stool comes out tar-black like black-bean sauce. That means bleeding is happening inside your body, so you need to get to the hospital without delay.
Beyond fever and bleeding, there are a few signs serious enough to call 911. Sudden shortness of breath or tightness in the chest, becoming confused or slurring your speech, a sudden splitting headache, or losing strength in an arm or leg on one side. And if vomiting or diarrhea won't stop and you can't keep down even water all day, dehydration and infection can pile on top of each other, so don't just try to tough it out. When something like this happens in the middle of the night, your mind tends to go blank, and that's precisely why you need to be ready ahead of time.
When your treatment began, the hospital most likely gave you a 24-hour contact number and ER guidance. Stick that number somewhere you'll see it, whether on the fridge or in your phone's favorites. Planning the route with your caregiver in advance helps a lot too. Decide which ER you'll go to, how many minutes it takes by car, and tuck a note with your chemo schedule and medication list into your bag. When you call the hospital, calmly tell them what your temperature is, when the symptoms started and what they are, and when your last chemo session was; it makes it much easier for the care team to judge the situation.
The saddest cases are when people suffer in silence on their own and end up calling too late. If it feels unclear, the right move is to just call and ask. There's no need to feel embarrassed about making a fuss over nothing; that's exactly what they're there for. What's written here is only general guidance, so be sure to confirm the precise thresholds that fit your own condition with your treating care team.