Sinus drainage occurs when excess mucus drains down the back of the throat. This post-nasal drip tends to trigger coughing, and contributes to the misery of allergy and cold symptoms.

Sinus pain and postnasal drip are usually symptoms of sinusitis, which is an inflammation of the sinuses with frequent thick nasal secretions that drip back in the throat when the person lies down.

Postnasal drip is responsible for 50 percent of lingering coughs that last more than three weeks, according to "Kelley's Essentials of Internal Medicine."

Mucus in the chest is a common result of bronchitis, allergies, post nasal drip and pneumonia. Choosing the right medication to reduce the amount of mucus in the chest depends on the condition causing it.

Postnasal drip is the sensation of accumulated or dripping mucus from the back of the nose. Chronic postnasal drip persists longer than two months and often occurs in conjunction with allergies, chronic sinusitis or gastroesophageal reflux disease.

Post nasal drip is a condition characterized by the sensation of constant mucus dripping from the nose through the back of the throat. This can result in various symptoms, depending on affected structures in the head and neck.

Allergies are known for their reactions in the body such as sneezing, coughing and asthma-like symptoms. A less common symptom associated with allergies is trouble swallowing.

One of the first symptoms of a cold in children is usually a runny nose, with clear, thin mucous, followed by aches, a sore throat or coughing. As the child recovers, the mucous may become brown or green, and usually becomes thicker.

The glands in the nose and throat produce mucus on a continuous basis. The American Academy of Otolaryngology Head and Neck Surgery points out that the secretions typically amount to between one and two quarts per day.

A fluid called mucus is produced by the nose to help warm and clean the air that is inhaled. This fluid is then swallowed in order to clean and moisten the back of throat. If there is excessive mucus production, or the mucus becomes thicker than normal, the symptoms of post nasal drip may appear.

As any tissue-toting parent can attest, a runny nose is unfortunately very common in toddlers. This symptom can be due to a variety of causes, including a head cold, the flu, allergies, a sinus infection or another infectious disease.

The sinuses are passages around your nose and forehead that help keep the nasal passages clean so dust, bacteria and other material doesn’t enter your body through your nose. Like the nasal passages, your sinuses produce a steady flow of mucus.