Is a Persistent Cough a Sign of Cancer?

This page is for anyone who has had a cough for weeks and wonders if it could be cancer. It covers how long is too long, when blood means you need help fast, and what else to watch for.

Coughs outlast the illness that started them. MedlinePlus says acute coughs, often from a cold, flu or sinus infection, usually go away after 3 weeks. Subacute coughs last 3 to 8 weeks. Chronic coughs last longer than 8 weeks.

MedlinePlus says to contact your provider right away if a cough lasts longer than 10 to 14 days. NCI gives a similar line for any symptom: if it lasts a couple of weeks, see a doctor. MedlinePlus lists other reasons to call alongside a lasting cough, including weight loss you did not intend, night sweats, fever, and thick, foul-smelling yellow-green phlegm.

Count from when the cough started, not from when you started worrying about it.

A long cough can wait for a regular appointment. Blood cannot. This is the part worth acting on straight away.

Phlegm is the mucus you bring up from your airways. MedlinePlus says to contact your provider any time you cough up blood, even if you do not have any other symptoms. That holds for a few small spots, flecks or streaks, and even when you feel perfectly well otherwise. Call your doctor that day.

MedlinePlus says to get medical help right away if you cough up more than a few teaspoons of blood. The same applies if coughing blood comes with chest pain, dizziness, lightheadedness, fever, severe shortness of breath, or blood in your urine or stools. CDC adds that trouble breathing, chest pain and a fast or irregular heartbeat with coughing up blood can be signs of a clot in the lung, which needs immediate care. For any of these, call 911.

Blood is not the only warning sign. The MedlinePlus cough page has its own lists.

Call 911 if you have a cough and:

• shortness of breath or difficulty breathing.
• hives, or a swollen face or throat with trouble swallowing.

Contact your provider right away if you have a cough and:

• a cough that began suddenly and is violent.
• a high-pitched sound when breathing in.
• fever.
• swelling in your legs, heart disease, or a cough that gets worse when you lie down.
• contact with someone who has tuberculosis.

If you have none of those warning signs, the likely cause is an everyday one. MedlinePlus lists the common causes of cough as:

• colds, flu and other viral infections
• lung infections such as pneumonia or acute bronchitis
• allergies, and sinus infections with drainage down the back of the throat
• asthma and COPD
• reflux, where stomach acid comes back up

Other causes it lists include smoking or secondhand smoke, and a class of blood pressure medicines called ACE inhibitors, which can cause cough as a side effect. Lung cancer is on its list of other causes too.

A chest X-ray that finds nothing worrying is a real answer, not a wasted trip.

The American Cancer Society says most lung cancers do not cause symptoms until they have spread, though some people with early lung cancer do have symptoms. Its list of the most common ones is:

• a cough that does not go away or gets worse
• coughing up blood or rust-colored phlegm
• chest pain that is often worse with deep breathing, coughing or laughing
• hoarseness
• loss of appetite or unexplained weight loss
• shortness of breath
• feeling tired or weak
• infections such as bronchitis and pneumonia that don't go away or keep coming back
• new wheezing

NCI adds some less common signs: trouble swallowing, swelling of the face and neck veins, and, infrequently, finger clubbing, where the fingertips become wider and rounder.

These symptoms can have many causes. Any of them lasting more than a couple of weeks is a reason to see a doctor.

If you are having chemotherapy, a cough is handled differently. The immune system may be too weak to contain an infection.

CDC says to call your doctor right away for a temperature of 100.4 F (38 C) or higher. It says this is an emergency: call even in the middle of the night, and do not wait until morning. If you cannot reach your care team quickly, go to the emergency room and say you are on chemotherapy.

CDC also says to call right away for a new cough or a change in your cough, chills and sweats, a sore throat or new mouth sore, shortness of breath, or diarrhea. Infections during cancer treatment can be life threatening, NCI says, and need urgent medical attention.

NCI also says to talk with your doctor or nurse before taking acetaminophen, ibuprofen or aspirin for a fever, since they can hide the signs of a more serious problem. Use the number your team gave you. Symptoms of Cancer has more on tracking a symptom over weeks.

• MedlinePlus — Cough
• MedlinePlus — Coughing up blood
• CDC — Blood clots and cancer
• CDC — Preventing infections in cancer patients
• American Cancer Society — Signs and symptoms of lung cancer
• National Cancer Institute — Symptoms of Cancer
• National Cancer Institute — Non-Small Cell Lung Cancer Treatment (PDQ), Health Professional Version
• National Cancer Institute — Infection and Neutropenia during Cancer Treatment