Should visitors avoid me if they have a cold?
Yes. "Stay away from people who are sick or have a cold" is the National Cancer Institute's own wording. MedlinePlus puts it the same way and adds a step further out: avoid people who have been exposed to someone sick, not only people who are sick themselves.
Why an ordinary cold is not ordinary here
Some cancers and some treatments lower the number of white blood cells. Those are the cells that fight infection.
The specific cell is the neutrophil. During chemotherapy there are stretches in each cycle when the neutrophil count drops and infection risk climbs. That low state has a name: neutropenia.
MedlinePlus gives the numbers. An adult with fewer than 1,000 neutrophils in a microliter of blood has neutropenia. Below 500 is called severe neutropenia. At that level, MedlinePlus notes, even the bacteria that normally live in a person's mouth, skin, and gut can cause serious infections.
That is the real reason a visitor's cold matters. The problem is not the cold virus alone. It is that a body with few neutrophils handles any germ badly, and NCI warns that infections during cancer treatment can be life threatening.
The rest of the visiting rules
NCI lists several precautions that sit alongside this one.
- Avoid crowds.
- Avoid anyone who has just had a live vaccine, such as one for chicken pox, polio, or measles.
- Have everyone nearby wash their hands well, with soap and warm water.
MedlinePlus adds practical detail for households: plan errands for quieter hours, wear a mask around other people, and use sanitizing wipes before touching public surfaces such as doorknobs and railings.
A standing house rule is easier than a fresh conversation each time. Something like "if anyone is under the weather, we will pick another day" spares everyone the awkwardness. Our guide to visitors and infection risk covers how to say it, and the piece on infection and neutropenia covers the blood counts behind it.
Two federal pages give two different fever numbers
This is worth knowing, because the number is the thing people are told to watch.
NCI lists "fever of 100.5 °F (38 °C) or higher" as a sign of infection. Those two figures do not match each other. 38 °C is 100.4 °F, not 100.5 °F.
MedlinePlus uses 100.4 °F (38 °C), and its page was reviewed on October 11, 2024. NCI's infection page was last updated on January 23, 2020. The more recent page is also the internally consistent one.
The practical answer is to use the number the treating team gives, because many centers set their own threshold, and some ask for a call at a lower one.
What to report, and when
Beyond fever, NCI lists chills, cough or sore throat, diarrhea, ear pain, headache or sinus pain, a stiff neck, skin rash, mouth sores or white coating, swelling or redness where a catheter enters the body, and cloudy or bloody urine or pain on urinating.
One NCI instruction gets missed. Check with the doctor or nurse before taking anything for a fever, including acetaminophen or ibuprofen. Those drugs lower a fever, and in doing so they can hide a serious problem.
MedlinePlus adds symptoms that warrant a call even without fever: diarrhea that will not stop or is bloody, severe vomiting, being unable to eat or drink, extreme weakness, trouble breathing at rest, a very bad headache, or drainage from an IV site.
Sources
Want the full picture? Read our complete explanation: Can I Have Visitors During Cancer Treatment?
Know someone who needs this?
Plenty of people are looking for something like this and do not know where to start. If this would help a friend or someone you love, send it on — we have written an opening line so you do not have to stare at an empty message. You can change every word of it.
Your message is written and sent in your own email or messaging app — we never see who you send it to, and nothing is added to any list.