Coughing is an important way to keep your throat and airways clear. However, excessive coughing may mean you have an underlying disease or disorder.

Some coughs are dry, while others are considered productive. A productive cough is one that brings up mucus. Mucus is also called phlegm or sputum.

Coughs can be either acute or chronic:

• Acute coughs usually begin suddenly. They are often due to a cold, flu, or sinus infection. They usually go away after 2 to 3 weeks.
• Chronic coughs last longer than 2 to 3 weeks.

Besides recent upper airway infections such as the common cold and flu, other common causes of coughs include:

• Allergies and asthma
• Lung infections such as  pneumonia or acute bronchitis
• Chronic obstructive pulmonary disease (emphysema or chronic bronchitis)
• Sinusitis leading to postnasal drip
• Lung disease such as bronchiectasis, interstitial lung disease, or tumors
• Gastroesophageal reflux disease (GERD)
• Cigarette smoking
• Exposure to secondhand smoke 
• Exposure to air pollutants
• ACE inhibitors (medications used to control blood pressure)

If a child has a barking cough, see croup.

Here are some tips to help ease your cough:

• Cough lozenges or hard candy can help dry, tickling coughs. These should never be given to a child under 3 years old because they may cause choking.
• A vaporizer or steamy shower may help a dry cough by increasing the humidity in the air.
• Drink extra fluids to help thin the secretions in your throat and make them easier to cough up.

Medications available without a prescription include:

• Guaifenesin (like Robitussin) can help you bring up mucus. Drink lots of fluids if you take this medicine.
• Decongestants such as pseudoephedrine (Sudafed) can be used to clear a runny nose and postnasal drip. These should not be used if you have high blood pressure or for a child under 6 years old, unless prescribed by your doctor.

Although coughing can be a troubling symptom, it is usually your body's way of healing. Recent expert recommendations advise against using cough suppressants in many situations. You may want to talk to your doctor before trying over-the-counter cough suppressants such as dextromethorphan (Vicks 44, Robitussin DM).

Do not expect a doctor to prescribe antibiotics for viral infections like colds or flu. Antibiotics do not work on viruses. Antibiotics also will not help coughs from allergies.

Call 911 if you have:

• Shortness of breath or difficulty breathing
• Hives or swollen face or throat with difficulty swallowing

Call your doctor right away if you have:

• Violent cough that begins suddenly
• High-pitched sound (called stridor) when inhaling
• Cough that produces blood
• Fever (may indicate a bacterial infection requiring antibiotics)
• Thick, foul-smelling, yellowish-green phlegm (may indicate a bacterial infection)
• A history of heart disease, swelling in your legs, or a cough that worsens when you lie down (may indicate congestive heart failure)
• Exposure to someone with tuberculosis
• Unintentional weight loss or night sweats (may also indicate tuberculosis)
• Cough longer than 10-14 days
• Cough in an infant less than 3 months old

In emergency cases, the patient will be treated first to stabilize the condition. After the condition is stable, the doctor will ask questions about your cough, including:

• Are you coughing up blood? (How much, how often)
• Do you bring up any mucus/sputum when you cough? What does it look like? Is it thick and hard to cough up? How much sputum is produced per day?
• Is the cough severe? Is the cough dry?
• Does the cough sound like a seal barking?
• What is the pattern of the cough? Did it begin suddenly? Has it been increasing recently? Is the cough worse at night? When you first awaken?
• How long has the cough lasted?
• Is the cough worse when you are lying on one side?
• Are there sudden periodic attacks of coughing with gagging and vomiting?
• What other symptoms are present?

The physical examination will include emphasis on the ears, nose, throat and chest.

Diagnostic tests that may be performed include:

• Bronchoscopy
• Lung scan
• Pulmonary function tests
• Sputum analysis (if the cough produces sputum)
• X-ray of the chest

• Don't smoke and stay away from secondhand smoke.
• If you have seasonal allergies like hay fever, stay indoors during days when airborne allergens are high. If possible, keep the windows closed and use an air conditioner. Avoid fans that draw in air from outdoors. Shower and change your clothes after being outside.
• If you have allergies year round, cover your pillows and mattress with dust mite covers, use an air purifier, and avoid pets and other triggers.

Irwin RS, Baumann MH, Bolser DC, et al. Diagnosis and management of cough executive summary: ACCP evidence-based clinical practice guidelines. Chest. 2006;129(1 Suppl):1S-23S.

Chang AB, Glomb WB. Guidelines for evaluating chronic cough in pediatrics: ACCP evidence-based clinical practice guidelines. Chest. 2006;129(1 Suppl):260S-283S. Review.

Holmes RL. Evaluation of the patient with chronic cough. Am Fam Physician. 2004; 69(9): 2159-2166.