What is a common cause of thick sputum?

Thick sputum is often a result of dehydration and the use of antihistamines. When the body becomes dehydrated, the mucus production can decrease its water content, leading to thicker, stickier secretions. Antihistamines, which are medications commonly used to relieve allergy symptoms, can dry out mucous membranes and further contribute to the thickness of sputum. This combination results in sputum that is less fluid and more viscous, making it harder to expel.

Other factors like bleeding from the lungs, allergic reactions, and air pollution can affect respiratory health but are less directly related to the viscosity of sputum. Bleeding may lead to different symptoms such as coughing up blood, while allergic reactions could cause more watery mucus production. Air pollution can irritate the respiratory tract but does not specifically cause thick sputum in the same straightforward way as dehydration and antihistamine use.