What to Do If You Get a Cold While on Chemo

Call your oncology team right away, even if your symptoms feel mild. A cold that would be a minor inconvenience for a healthy person can escalate quickly when chemotherapy has suppressed your immune system. The standard advice from cancer care guidelines is to phone your oncologist’s office or the on-call nurse at the first sign of respiratory symptoms, and certainly before taking any over-the-counter medications. What follows after that call depends on where you are in your treatment cycle, what your blood counts look like, and whether a fever develops.

Why a Cold Is a Bigger Deal During Chemotherapy

Chemotherapy drugs target rapidly dividing cells, and that includes the white blood cells your body relies on to fight infection. The result is a condition called neutropenia, where your supply of neutrophils (the white blood cells that respond first to bacteria and viruses) drops well below normal levels. Patients with chemotherapy-induced neutropenia face heightened vulnerability to viral, bacterial, and fungal infections.¹ The deeper and longer your neutrophil count stays low, the greater the danger. Research has found that each additional day a patient spends with severely low counts is associated with roughly a 28 to 30 percent increase in the risk of an infection-related hospitalization.²

This does not mean every sniffle will land you in the hospital. But it does mean your body may not be able to contain a run-of-the-mill cold virus the way it normally would. What starts as a scratchy throat can progress to a lower respiratory infection, pneumonia, or a secondary bacterial infection that takes hold because your weakened immune system cannot mount a proper defense. In healthy people, respiratory virus reinfections are generally mild and often go undiagnosed; in immunocompromised patients, the consequences of these same common viruses are far more serious.³

The Fever Question

The single most important thing to monitor when you have cold symptoms during chemo is your temperature. A fever of 100.4°F (38°C) or higher in a patient with low white blood cell counts is treated as a medical emergency called febrile neutropenia. Delays in starting appropriate antibiotic therapy for febrile neutropenia can be life-threatening.⁴ Clinical guidelines from the American Society of Clinical Oncology and the Infectious Diseases Society of America recommend that patients with febrile neutropenia receive the first dose of antibiotics within one hour of being seen.⁵

So even if you think you just have a cold, check your temperature regularly. Many oncology teams tell patients to take their temperature twice a day during their most vulnerable period (typically 7 to 14 days after a chemo infusion, when counts hit their lowest point, called the nadir). If it crosses that 100.4°F threshold, head to the emergency department or call your oncologist immediately. Do not wait to see if the fever breaks on its own. Do not take acetaminophen or ibuprofen to bring it down before calling, because masking the fever can delay the care you need.

Not all colds produce a fever, though, and the absence of fever does not mean you are in the clear. Persistent cough, worsening congestion, shortness of breath, chills, or feeling significantly worse than your usual chemo fatigue all warrant a call to your care team. They would rather hear from you about something that turns out to be minor than miss an infection that escalates.

What Happens When You Call Your Oncology Team

When you phone in with cold symptoms, your team will triage you based on several factors: how recently you received chemo, what your last blood counts were, whether you have a fever, and the severity of your symptoms. In many cases, they will ask you to come in for blood work and a physical exam. If the concern is high enough, they may send you straight to the emergency department.

Accurate triage matters. A study of cancer patients with febrile neutropenia found that when the initial triage in the emergency department was inaccurate or underestimated the severity, it significantly delayed the first physician assessment and the start of antibiotics.⁶ This is one reason oncologists often prefer that patients call the cancer center first rather than just walking into a general urgent care clinic. Your oncology team knows your blood counts, your treatment schedule, and the specific risks of your regimen. A general triage nurse may not immediately recognize that your “cold” requires a very different level of response than it would in someone not on chemotherapy.

If your team suspects a respiratory virus, they will likely test for it. Guidelines from the German Society of Haematology and Medical Oncology recommend combined nasal and throat swabs tested with molecular methods (PCR-based tests) for the most reliable detection of respiratory viruses in immunosuppressed cancer patients. Standard rapid antigen tests are considered less reliable in this population.⁷ Identifying the specific virus helps your team decide whether antiviral treatment is appropriate and whether your chemo schedule needs adjustment.

Over-the-Counter Medications and What to Avoid

One of the most common instincts when you get a cold is to reach for whatever is in the medicine cabinet. During chemo, that instinct needs a pause. Some over-the-counter cold remedies can interact with your chemotherapy drugs, affect your blood counts, or mask symptoms your care team needs to see.

A few specific concerns to be aware of:

Fever-reducing drugs: As mentioned above, taking acetaminophen or ibuprofen before contacting your team can obscure a fever. Some oncologists allow acetaminophen in limited situations, but ibuprofen and aspirin carry additional risks because they affect platelet function, and chemo may already have lowered your platelet count.
Decongestants: Some decongestants can raise blood pressure or interact with other medications in your treatment plan. Always clear these with your team.
Herbal remedies and supplements: Products like echinacea, elderberry, or high-dose vitamin C are marketed for immune support, but some can interfere with how your body processes chemotherapy drugs. The liver enzymes responsible for metabolizing many chemo agents can be affected by herbal compounds in unpredictable ways.
Multi-symptom formulas: Combination cold products (the ones labeled “cold and flu relief”) contain several active ingredients at once, which multiplies the chance of a problematic interaction. It is safer to use single-ingredient products after getting the okay from your pharmacist or oncologist.

The practical takeaway is simple: call before you take anything. Your oncology team or the cancer center pharmacist can tell you exactly what is safe given your specific regimen and current blood work.

Will Your Chemo Be Delayed?

This is often the question that causes the most anxiety. You are already dealing with cancer; the idea that your treatment might be paused feels like losing ground. But there are situations where a short delay is the safer choice.

If your white blood cell counts are very low and you are actively fighting an infection, pushing forward with another round of chemo could suppress your immune system even further. In some cases, your oncologist will postpone the next cycle by a few days to a week until the infection clears and counts recover. Research on dose delays has found that they are more common in certain treatment scenarios. In a study of patients with diffuse large B cell lymphoma, for example, those who experienced more infections and febrile neutropenia had significantly higher rates of dose delays, and the proportion of patients receiving less than 80 percent of the planned dose intensity increased when infections complicated the schedule.⁸

A short delay does not necessarily compromise your treatment outcome. Oncologists weigh the risk of a brief pause against the risk of treating someone whose body is too depleted to handle another round. In many regimens, a one- or two-week delay is manageable. Your oncologist will adjust the schedule as needed and let you know whether the delay changes anything about your overall treatment plan. If you find yourself ruminating about it, bring it up directly with your team. They can put the delay in perspective relative to your specific cancer type and stage.

Growth Factors and Other Medical Interventions

If you have had repeated infections or your counts are persistently low, your oncologist may add a growth factor medication to your regimen. These drugs (filgrastim and pegfilgrastim are the most common) stimulate your bone marrow to produce white blood cells faster, substantially shortening the period of severe neutropenia that follows each chemo cycle.⁹ They are typically given as an injection one to three days after chemotherapy and are a standard tool for patients whose regimens carry a high risk of neutropenia.

For certain respiratory viruses, antiviral medications can help. If testing identifies influenza, for example, early treatment with antiviral drugs improves outcomes in cancer patients, though the optimal approach is still not precisely defined for every scenario.¹⁰ For other common cold viruses like rhinoviruses or non-COVID coronaviruses, there are no specific antiviral treatments; supportive care, rest, and hydration remain the approach, with close monitoring to catch any secondary bacterial infection early.

Preventing Colds During Chemo

Prevention is far easier to manage than treatment. Your oncology team will likely give you a rundown of infection-prevention measures before you start chemo, but here is what the evidence supports:

Hand hygiene is the single most effective measure. Wash your hands frequently with soap and water, especially before eating, after being in public, and after touching common surfaces. Carry hand sanitizer for situations where soap is not available. This sounds basic, but most respiratory viruses spread through contaminated hands touching the face far more efficiently than through airborne transmission alone.

Avoid crowded indoor spaces during your nadir period. If you must go out, a well-fitting mask provides meaningful protection. Research has shown that fit-tested N95 respirators combined with portable HEPA air filtration can reduce airborne viral loads to near-zero levels even during prolonged close-range exposure.¹¹ You do not need a full hospital-grade setup at home, but a portable HEPA air purifier in the room where you spend the most time is a reasonable investment, and wearing a good-quality mask in public is one of the simplest ways to reduce your risk.

Vaccination matters, both yours and the people around you. The concept of “cocooning” means that household members and close contacts get vaccinated to reduce the chance of bringing an infection home. An ASCO guideline on vaccination for adults with cancer explicitly states that vaccination of household contacts enhances protection for patients.¹² Ask your family members and anyone who visits regularly to stay current on flu and COVID vaccines. Your own vaccine response during chemo may be blunted because your immune system is suppressed, so having a wall of vaccinated people around you provides an additional layer of defense.

At home, basic steps help: ask anyone with cold symptoms to stay away or, if they live with you, to wear a mask and stay in a separate room when possible. Wipe down shared surfaces like doorknobs, light switches, and counters. These are not dramatic measures, just consistent ones.

The Emotional Side of Getting Sick During Treatment

Getting a cold during chemo often triggers an outsized wave of anxiety that goes well beyond the physical symptoms. You are already coping with a cancer diagnosis, and a new illness feels like your body is failing you. Research during the COVID-19 pandemic found that anxiety about viral infections was strongly linked to fear of cancer progression among cancer patients, and that patients who fell into catastrophic thinking patterns had an even harder time coping.¹³ The worry that a cold could delay treatment or spiral into something dangerous is real and legitimate, but it can also amplify itself into a level of distress that is not proportional to what is actually happening.

A few things help. First, having a clear action plan in advance reduces panic when symptoms appear. Know your oncologist’s after-hours number. Know at what temperature you should go to the emergency department. Know which medications you can and cannot take. When you have a checklist, a cold becomes a problem to manage rather than a crisis to react to. Second, if you find yourself spiraling into worst-case scenarios, talk to your care team or a psycho-oncology counselor. The worry itself is not a weakness; it is a known and documented pattern among cancer patients facing infection risk, and there are concrete coping strategies that help.

When Someone in Your Household Gets Sick First

Often the cold is not yours yet but a family member’s. A partner comes home sniffling, or a child brings something back from school. This is where household planning pays off.

Ideally, the sick person isolates in a separate room and bathroom for the duration of their symptoms. If that is not practical, focus on the measures with the best evidence behind them: the sick person wears a mask in shared spaces, both of you practice frequent handwashing, and you avoid sharing utensils, towels, and close face-to-face contact. A HEPA air purifier running in the shared living space adds another layer. If you have the option, sleep in separate rooms until the other person is symptom-free for at least 24 hours.

Alert your oncology team that you have a sick household contact. They may want to check your blood counts sooner than planned, adjust your chemo schedule to avoid hitting your nadir while the household virus is still circulating, or prescribe a prophylactic antiviral if influenza is involved. The earlier your team knows about the exposure, the more options they have to protect you.

Children are a particular challenge because they catch respiratory infections frequently and are not always great at covering coughs or washing hands. If you have young children at home and are going through chemo, enlisting help from a family member or friend to handle bedtime and close-contact caregiving during peak illness days is a practical step that reduces your exposure without isolating you from your kids entirely.

When to Go to the Emergency Department

In most cases, a phone call to your oncology team is the first step. But certain situations should send you directly to the emergency department without waiting for a callback:

Fever of 100.4°F or higher: Especially if you are within two weeks of a chemo infusion. This is the defining criterion for febrile neutropenia.
Difficulty breathing: Shortness of breath, rapid breathing, or a feeling of not being able to get enough air.
Confusion or altered mental state: Infection in a neutropenic patient can progress to sepsis, and confusion is an early warning sign.
Persistent vomiting or inability to keep fluids down: Dehydration on top of an infection compounds the danger.
Shaking chills or rigors: Intense shivering even under blankets, often a sign your body is mounting a serious inflammatory response.

When you arrive at the emergency department, tell triage staff immediately that you are on chemotherapy. This information should change how quickly you are assessed. As noted earlier, inaccurate triage in the emergency setting delays antibiotic administration and other critical interventions.⁶ Carrying a card or a note from your oncologist that lists your diagnosis, your chemo regimen, and the date of your last treatment can speed things up considerably. Some cancer centers provide these cards specifically for emergency situations.

If you are sent home from the emergency department or after an urgent clinic visit, pay close attention to the discharge instructions about what to watch for in the next 24 to 48 hours. A cold that initially looks manageable can shift, and knowing when to come back is just as important as knowing when to go in the first place.