It is natural to feel frightened when you find it difficult to get enough air. Also called dyspnea, shortness of breath can be a terrible sensation and is usually characterized by a feeling of suffocation or an intense tightening in the chest. The problem can develop suddenly or may have a gradual onset. It is hard to pinpoint the real causes considering many factors can contribute to this problem. The most common causes include allergies to mold, dust, or pollen; obesity; blocked air passages; stress and anxiety; or restricted oxygen intake from climbing to a high altitude. Sometimes, shortness of breath indicates a serious medical condition, so it makes sense to talk to your doctor for a correct diagnosis.

Causes of Shortness of Breath

In some cases, shortness of breath is related to the problems of the organs like the heart or lungs that transport oxygen to the tissues and remove carbon dioxide. Some common cases are listed below.

Lung Problems

Your lungs help you breathe, and if there is a problem with breathing, there may as well be an issue with your lungs. Here are some common lung problems that may lead to shortness of breath.

• Infections: You may experience shortness of breath due to recent infections such as pneumonia or bronchitis. This may also happen due to chronic infections such as chronic bronchitis or tuberculosis.
• Chronic Obstructive Lung Disease (COPD), Asthma, and Emphysema: All these conditions lead to the narrowing of the airways that increases resistance to exhaling air from the lung. This sometimes leads to air entrapment in the lung. If this is the reason of shortness of breath in your case, you may also hear wheezing while breathing.
• Lung Cancer: Shortness of breath may sometimes indicate lung cancer or other tumors, but there may also be other symptoms such as weight loss and unintentional appetite.
• Damage of Lung Tissue: The lung tissue damage is one of the causes of shortness of breath. Any systemic illness such as rheumatoid arthritis or exposure to asbestos or other toxins can cause scarring of lung tissue. 
• Clot: Pulmonary embolus or clot in the lung circulation may result in breathlessness. You may also experience rapid breathing and chest pain. You are likely to develop this condition if you have a debilitating medical condition, are immobile, or have a family history of forming clots.
• Problems with the Lung Sac: Breathlessness may indicate problems with the lung sac. This usually happens when the lung sac becomes scarred, thickens, or gets filled with blood or fluid because of infection.
• Pneumonia: It is the infection of the lung that leads to inflammation and causes several symptoms including chest pain, cough, shortness of breath, muscle plain, fever, sweating, chills, and exhaustion. If left untreated, it may lead to serious complications.
• Pulmonary Hypertension: Caused by the hardening or narrowing of the lung arteries, the condition leads to an increase in blood pressure and usually requires immediate medical attention.
• Croup: This respiratory condition is the result of an acute viral infection and produces loud and 'braking' cough. Be sure to talk to you doctor immediately if you have croup. The condition is more common in children under three years of age.

You may also experience breathing difficulties due to other lung problems such as pleural effusion that leads to a buildup of fluid next to your lung and bronchiectasis that leads to the widening of the airways.

Heart Problems

You may have breathing difficulties and experience shortness of breath if you have certain heart problems.

• Heart Failure: Breathlessness is one of many signs of heart failure. It increases pressure in the blood vessels around your lungs. Symptoms such as breathlessness when lying down, wakefulness at night due to shortness of breath, feeling an urge to keep the head of the bed elevated, swelling of ankles or legs, fluid weight gain, and unusual fatigue with activity indicate potential heart failure.
• Heart Rhythm Problems: Irregular heartbeat ia another one of the causes of shortness of breath which makes it difficult for your heart to deliver enough oxygen throughout the body. This makes you take deep breaths to fill your lungs with more oxygen.
• Coronary Artery Disease: The disease makes your arteries to become narrow and hard, which leads to an increase in your blood pressure. You may also have chest pain with coronary artery disease.
• Congenital Heart Disease: You develop this disease when you have inherited problems with the functioning or structure of the heart.

Systemic Illness Problems

Certain systemic illnesses may also contribute to shortness of breath and other breathing problems.

• Anemia: You develop anemia when your red blood cell count is on the lower side. It means your red cells cannot transport enough oxygen to all parts of your body and this may result in shortness of breath.
• Increased Metabolic States: Issues like severe systemic infection, extremely low blood pressure, or fever may also increase your body's demand for oxygen and this makes you breathe deeply to get more oxygen.
• Chronic Liver or Kidney Problems: These problems will lead to impaired oxygen exchange in the lungs, which in turn will lead to breathlessness.

What's more, you may feel out of breath when you have excessive acid in the blood (metabolic acidosis). Similarly, sudden worsening of diabetes, severe kidney failure, and ingestion of certain drugs may also be among the causes of shortness of breath.

Nervous System Problems

Any problems associated with your nervous system may produce many symptoms including breathlessness.

• Increased Pressure in the Brain: This may happen due to stroke, tumors, trauma, or bleeding. There may be damage to the portion of brain responsible for regulating respirator, which leads to breathing difficulties.
• Muscle and Nerve Disorders: These disorders will affect your body's ability to expand your chest, which in turn will affect the movement of the diaphragm. This can cause shortness of breath in many cases.
• Anxiety Disorder: You are more likely to feel out of breath or hyperventilated when you are anxious. The shortness of breath usually relieves when the anxiety ends.

When to See a Doctor

If you just recently started experiencing breathlessness and the sensation is severe, you should go talk to your doctor for a correct diagnosis. Call the local emergency number if someone has stopped breathing completely. you should also consult your doctor if breathlessness comes with other symptoms such as fever, chest discomfort, wheezing, tightness in the throat, agitation, a decreased level of consciousness, night sweats, or weight loss. It is important to visit your healthcare provider if you have choked on an object, your shortness of breath wakes you up in the middle of the night, or you feel out of breath after slight activity or while at rest.