Persistent Cough: 6 Common Causes & What to Do

Updated in December 2021

A persistent cough, which normally worsens at night, can have many different causes behind it. The most common cause, however, is an allergic reaction to an irritant, In this case, the best way to treat the cough is to decrease allergy sensitivity with the use of an antihistamine (like loratadine). You should also identify the initial trigger and reduce exposure to it

There are other reasons that can cause a persistent cough, like exposure to pollution, cigarette use, or a history of cardiac or respiratory illness.

Nonetheless, if your cough lasts for over a week, if it worsens, or if other symptoms are present (like thick sputum, blood with coughing, fever or difficulty breathing), you should seek medical attention, either from your family doctor or the emergency room. The cause should be identified and treatment should be initiated if necessary.

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The most common causes of a persistent cough include:

1. Respiratory allergies

Allergies to dust, pet fur or pollen can cause throat irritation, which can stimulate coughing. You may not know you have an allergy until it is properly identified and the trigger is eliminated. Allergy-related coughing happens most frequently in the spring and fall.

What to do: Identifying the trigger is fundamental, as it is the only way to prevent future allergy flare-ups. You can also opt to use antihistamine medication to help relieve any allergy-related symptoms.

2. Cigarettes and pollution

Cigarette use, second-hand smoke or any type of environmental pollution can cause throat irritation which can stimulate the cough reflex. Coughs due to poor air quality tend to be dry and very persistent.

What to do: You should avoid exposure to these types of environments, and should quit smoking if you are a smoker. This way you can prevent any throat irritation and therefore avoid the development of a cough or other health problems that can come from poor air quality. 

3. Asthma

Asthma is a respiratory condition characterized by chronic inflammation of the lungs. In addition to a persistent dry cough, common symptoms also include shortness of breath, wheezing and a feeling of pressure on the chest.

What to do: It is important to follow treatment as indicated by your doctor, which may include the use of bronchodilator inhalers to improve breathing and relieve symptoms. It is also important to know what triggers yours symptoms in order to prevent frequent asthma attacks in the future.

4. Gastroesophageal Reflux Disease (GERD)

Coughing can be a symptom of gastroesophageal reflux disease (also known as GERD or acid reflux), especially after eating very spicy or acidic foods. Coughing occurs because certain foods can cause acid from the stomach to back-up to the esophagus during digestion. In addition to coughing, other symptoms of GERD include a sensation of fullness in the throat, heartburn and indigestion. Learn about the other symptoms of GERD and how it is treated.

What to do: In order to relieve symptoms of GERD, your day-to-day diet should consist of light meals that do not contain fatty foods. You doctor may also prescribe medication that helps to decrease or neutralize stomach acid production.

5. Cardiac problems

Some cardiac abnormalities, like heart failure, can result in an accumulation of fluid in the lungs. This can cause a frequent need to cough. In addition to coughing, some people may experience chest pain, shortness of breath at rest, lower extremity swelling and frequent fatigue.

What to do: A consult with a cardiologist is highly recommended to identify the cause of the cause and to start treatment as needed. Treatment in this case is not only aimed at treating the cough, but at resolving or managing the cardiac issue.

6. COVID-19

COVID-19 is a respiratory infection that can cause a dry, persistent cough as well as difficulty breathing, runny or stuffed nose, fever over 38ºC (or 100.4ºF) and generalized fatigue due to compromised lung function.

What to do: If you suspect you have COVID-19, you should complete a rapid-antigen test and/or a PCR test to confirm the infection. You should go into isolation while you await results and continue isolation if the infection is confirmed to prevent transmission of the virus to others. If you have difficulty breathing, proceed to the emergency room. A chest x-ray may be completed to assess your lungs and to determine the need for admission.

How to treat a persistent cough

Treatment of a persistent cough should be aimed at figuring out what its initial cause is. If the cough is caused by an allergy, in addition to using medication as prescribed by the doctor, you can also try:

  • Drink at least 1.5L (or 12 cups) of water per day to ensure moist airways and prevent throat irritation
  • Drink 1 cup of mint tear about 3 times per day. Mint is a natural decongestant and has soothing, antitussive properties that can help with mucus management. To prepare this tea, add 1 teaspoon of dry or fresh mint leaves to a cup of boiling water and let it soak for 5 minutes. Strain the tea with a mesh sieve and drink.
  • Take cough medicine as prescribed by your doctor. Some over-the-counter options include Robitussin, Dimetapp, Nyquil, Mucinex and Buckleys.
  • Avoid dust from accumulating in your home, as well as any other potential triggers like contact with pets and cigarette smoke

Persistent coughs that last for over a week require medical attention, especially if the individual has a chronic respiratory illness like asthma, bronchitis or sinus infections. Coughing in these cases can mean the illness is worsening or flaring-up, and may require medication for treatment (e.g. anti-histamines or corticosteroids).