Why Does My Eye Twitch?

A Runny Nose

What’s happening? When you have a runny nose, your body is responding to an invader, such as an allergen, a virus, or bacteria. Your immune system creates an inflammatory response, which increases blood flow to the area; this brings more blood cells to help fight the infection or allergen and also produces more mucous (which is normally present to keep your airways moist but is overproduced when you have a cold). In the case of an infection, the mucous helps surround and trap it, while immune cells in the small blood vessels that line your nose attack it. With allergies, the histamine cells in your nasal passages act up, creating inflammation. Mucous alone makes for a runny nose; accompanied by a lot of inflammation, it turns into a stuffed-up nose. “Sometimes the response can be too much,” says Dale Amanda Tylor, M.D., assistant professor of otolaryngology at Vanderbilt University in Nashville, Tennessee, “so your nose is completely blocked off or you have a hard time breathing or sleeping.”

Why is your body doing it? For the most part, a runny nose is the result of your body’s efforts to trap foreign invaders and kill them with special immune cells. But there can be other causes. Eating spicy foods, smelling certain scents (or irritants, such as smoke), or experiencing an abrupt change in climate (such as coming into a warm house from the cold outdoors) can also trigger a runny nose. This is thanks to your parasympathetic nervous system (the part of your nervous system that governs functions like salivation and digestion) going into high gear. Some people also experience a runny nose when they cry. In that case, tear ducts blocked by overflow can drain down into the nose, but what actually runs out of it is tears, not mucous. In rare instances, a genuine runny nose can be a sign of serious illness.

What should you do? Try an over-the-counter saline spray to help open up your nasal passages and improve drainage. If the stuff coming out is clear or white, chances are you don’t have an infection and the instigator is more likely to be allergies. When the drainage looks green, it’s more likely you have a bacterial infection (possibly in your sinuses, especially if you’re also experiencing facial or dental pain); you should check in with your doctor to see if you need antibiotics. Get to the doctor, too, if you are producing clear or white drainage for an extended period—two weeks or more: In highly uncommon, though dangerous, instances, chronic clear nasal discharge with a salty taste that is accompanied by a headache (or follows some kind of head trauma) could be an indication that you are leaking spinal fluid, says Tylor.