Sometimes mucus gets thicker when we’re fighting off an infection. But it can also be thin and runny. It all depends on the type of virus or irritant activating the body’s mucus-producing tissues, explains Chandra Ivey, MD, a private-practice laryngologist and assistant clinical professor at the Icahn School of Medicine at Mount Sinai in New York City.
Smokers, for example, tend to have more mucus and thicker mucus, she says. In the case of a cold, a thicker wall of mucus can serve as a barrier preventing other viruses, bacteria, or irritating particles from entering the nasal membranes, she says.
Mucus can also get thicker if you’re taking certain medications that dehydrate your body, she adds. That’s another good reason to get extra liquids when you’re sick.