Summarize this article in one sentence.
If you’re congested and your cough is not productive (nothing comes up when you cough), an expectorant can help loosen up the phlegm in your lungs. Many brands of expectorant (such as Robitussin and Mucinex) are available over the counter. Be sure to follow the dosage instructions printed on the packaging.  Some expectorants and may not be available to minors (anyone under 18). If you have a child under 18, consult with a doctor before giving them an OTC expectorant.  Expectorants that contain the drug Guaifenesin should not be taken by individuals who have asthma or who are chronic smokers. Taking expectorants containing Guaifenesin when you have asthma or smoke regularly can cause mucus to build up in your airways. Many expectorants contain acetaminophen, which can cause liver damage in children, or in adults, if taken in amounts that exceed the recommended daily dosage. Always read the label on an expectorant carefully. If the expectorant by itself isn’t clearing the congestion from your lungs, couple it with a mucolytic. Mucolytics thin mucous in your lungs and make the phlegm easier to cough up.  Mucinex (a brand name for Guaifenesin) is a common over-the-counter brand of mucolytic. Drink lots of water when you take a mucolytic to help it work better. If over-the-counter medication doesn’t cure your lung congestion in a few days, make an appointment to see your doctor. Although lung congestion is typically caused by a minor issue (like the common cold), chronic or painful chest congestion that lasts more than a week can be a sign of a serious infection or illness, including emphysema, bronchitis, or pneumonia. Each of these conditions can be accompanied by difficulty breathing and a painful (typically dry) cough. Other possible conditions include:  Asthma. Reactive airway disease. Cystic fibrosis. Other symptoms of cystic fibrosis include sticky, thick mucous, wheezing, and frequent lung infections.  Pulmonary fibrosis. Other symptoms of pulmonary fibrosis include shortness of breath, weight loss, and painful joints or muscles.  Chronic Obstructive Pulmonary Disorder (COPD). COPD is most commonly caused by frequent cigarette smoking, chronic bronchitis, or emphysema. Symptoms include a shortness of breath and a chronic cough (which produces large amounts of mucus) for at least 3 months a year for 2 years.

Summary:
Take an expectorant. Loosen the mucous in your lungs with a mucolytic. Consult your physician if the congestion persists.