Is a cough that won’t quit a sure sign of lung cancer, or could it be caused by another disease? How about persistent chest pain or shortness of breath? These and other symptoms of lung cancer overlap with several other medical conditions, including lung diseases like bronchitis and pneumonia, heart problems, and even allergies and asthma.

In addition, imaging tests like X-rays and CT scans can reveal lung conditions that look similar to malignant lung tumors. It’s important to get an accurate diagnosis so that you start the right treatment as soon as possible. The first step is to understand your symptoms and their possible causes. The following seven conditions produce similar symptoms to lung cancer.

1. Allergies and Asthma

Allergic reactions happen when your immune system attacks a foreign substance that made its way into your body, such as pollen. Allergies that affect the lungs can cause coughing attacks.

Asthma is a condition in which the lungs’ airways become inflamed and tighten, making it difficult to breathe. Asthma can cause shortness of breath and chest tightness, just as lung cancer does.

2. Pneumonia and Bronchitis

Pneumonia is a serious viral or bacterial lung disease that causes inflammation in the lung sacs (tiny pockets of air in the lungs). Bronchitis occurs when the bronchial tubes — the passages carrying air into and out of the lungs — become inflamed.

Pneumonia and lung cancer are easy to mistake for one another, as are bronchitis and lung cancer. The three conditions share several symptoms, including:

• Persistent coughing
• Chest pain
• Bloody phlegm
• Hoarseness
• Shortness of breath
• Extreme tiredness

Lung cancer can also cause pneumonia and bronchitis because tumors blocking air flow can trap germs and cause infections. Having several bouts of pneumonia and bronchitis can be a sign of lung cancer. In fact, 50 percent to 70 percent of people with lung cancer develop pneumonia at some point.

3. Chronic Obstructive Pulmonary Disease

Like pneumonia and bronchitis, chronic obstructive pulmonary disease (COPD) shares many symptoms with lung cancer. COPD and lung cancer symptoms include shortness of breath, chest pain and tightness, weight loss, and exhaustion, as well as frequent lung infections like bronchitis and pneumonia.

COPD is also associated with a higher risk of developing lung cancer. Every year, about 1 percent of people with COPD are diagnosed with lung cancer.

4. Lung Abscesses

Lung abscesses are areas of the lung where an infection has eaten into the inflamed tissue, creating a pus-filled cavity. Most lung abscesses occur when bacteria in the mouth are inhaled. This happens when someone is abnormally sleepy or unconscious because of using alcohol or recreational drugs, being under anesthesia, or having a disease of the nervous system. Poor immune system function can also cause lung abscesses.

As with lung cancer, lung abscesses can cause symptoms including fatigue and coughing up phlegm. Lung abscesses also can be a symptom of lung cancer — tumors in airways can prevent phlegm that’s full of bacteria from exiting the lungs.

5. Tuberculosis

Although still rare, tuberculosis is becoming increasingly common in the United States. This bacterial infection can lurk in the body for years without causing symptoms, which is known as latent infection. If your immune system can’t control the infection, the excess germs can lead to active tuberculosis and cause coughing (sometimes with blood), chest pain, weight loss, and exhaustion.

6. Pulmonary Edema

Pulmonary edema occurs when fluid from other parts of the body fills the lungs. Symptoms include breathing problems, wheezing, and tiredness. Unlike lung cancer, pulmonary edema usually causes weight gain, not weight loss.

Congestive heart failure is the most common cause of pulmonary edema. During congestive heart failure, the muscle in the left side of the heart is too weak to properly pump blood into the veins. Blood then pools in veins in the lungs and pushes fluid into the air sacs. Other causes of pulmonary edema include blood clots in the lungs, reactions to drugs, and high altitudes.

7. Benign Lung Nodules

Radiologists often do chest X-rays and CT scans for reasons other than lung cancer screening, and suspicious spots may show up on the lungs even outside a cancer screening. Called lung nodules, these lesions are simply spots where the lung tissue is unusually dense.

Lung nodules are common. About half of people who get a chest X-ray or CT scan will have a lung nodule appear. And although lung cancer can be a type of lung nodule, more than 95 percent of lung nodules aren’t cancerous.

Types of nodules include granulomas, which are clumps of immune cells that harden in areas where the lung was irritated, and hamartomas, which are benign masses made up of overgrown lung tissue. A condition called neurofibromatosis type 1 can cause lung nodules.

Getting a Diagnosis

If you’ve been experiencing symptoms that could suggest lung cancer, it’s important to check with your health care provider to prevent misdiagnosis. If scans reveal a suspicious spot, further imaging and other testing may be necessary. The only definitive way to reach a diagnosis of lung cancer is through finding cancer cells in mucus, lung fluid, or a tissue biopsy.

Talk With Others Who Understand

On MyLungCancerTeam, the social support network for people with lung cancer and their loved ones, more than 12,000 members come together to ask questions, give advice, and share their stories with others who understand.

Have you or a loved one experienced a lung cancer misdiagnosis? Share your insights in the comments below, or start a conversation by posting on your Activities page.