So, to answer your questions: The phlegm itself isn't toxic or harmful to swallow. Once swallowed, it's digested and absorbed. It isn't recycled intact; your body makes more in the lungs, nose and sinuses. It doesn't prolong your illness or lead to infection or complications in other parts of your body.

Is it better to spit or swallow mucus?

So here's the big question: Do you spit or swallow your phlegm? Even though it might taste nasty, “there's nothing wrong with swallowing it,” Dr. Comer says. In fact, that's probably what your body expects you to do, which is why phlegm naturally drains down into the back of your throat.

Is it OK to swallow mucus?

To spit or swallow? I'm occasionally asked whether swallowing mucus produced with a respiratory infection is harmful. It's not; luckily the stomach works to neutralise bacteria and recycle the other cellular debris. Some people do report a queasy feeling in the stomach during such infections.