You might think you're pretty knowledgeable about throwing up. After all, you've probably done it and you've likely seen other people do it, and it seems pretty straightforward. But there's more to puking than meets the eye. Here are a few facts that may surprise you. (Heal your whole body and feel better than ever with this 12-day liver detox from Rodale.)

It isn't always a stomach virus.

In children, vomiting can be a symptom of a migraine or even strep throat, says Lynn Lillie, MD, a family physician in Woodbury, MN, and a member of the American Academy of Family Physicians board of directors. In babies, recurrent spitting up may be a sign of acid reflux. In adults, sudden vomiting can signal an intestinal blockage. If illness doesn't abate after 48 hours or it comes on suddenly without any other virus-like symptoms (such as fever or diarrhea), call your doctor.

The color matters.

In general, what comes up when you're ill is just a mash up of what you last ate. But if your vomit is black, bright red, or looks like grape jelly, it could mean you’re throwing up blood, so call your doctor right away. 

It's not always a bad thing.

In pregnant women, nausea and vomiting during the first trimester tends to mean you have a lower chance of miscarriage, according to a study by the National Institute of Child Health and Human Development (these 13 remedies for morning sickness can help). And for non-pregnant people, vomiting is a way to get an infection out of your system, so stopping it can prolong your illness. That said, if vomiting is severe and causing additional issues—such as dehydration—you may need anti-nausea meds (here are 4 ways to tell if you're dangerously dehydrated).

Scientists have built a vomiting machine.

Researchers at North Carolina State University designed and built a machine to help them study the norovirus, which causes vomiting and diarrhea. A press release on the device described it as "a glorified air compressor with a grotesque clay face." The barfing machine is helping scientists determine how the virus is transmitted. (Holy cow: You’re not going to believe the unbelievable speed a virus can spread around your office.)

It might smell a little like Parmesan cheese.

In a study from Brown University, people were given a smell created by a chemical combination and told that it was Parmesan cheese—and they loved it. But when they were given the same smell and told it was vomit, they found the smell completely objectionable. Context has a lot to do with how we perceive the smell of something. 

You can have a phobia.

There is an official fear of throwing up, called emetophobia, and it's no laughing matter. People who have it may have paralyzing anxiety about their bodies, being around other people who may be ill, and germs in general. Feeling sick or seeing someone else vomit can bring on a panic attack. Treatment is difficult and can take significant time. (Skip these 5 totally useless things we all do to protect ourselves from germs.) 

It can be deadly.

Vomiting can usually be treated by drinking clear fluids, avoiding solid foods, and resting. But if you continue to vomit, you risk getting dehydrated, which has its own health risks. If you've been throwing up for more than four or five hours and you can't keep anything down—even water—go to urgent care or the ER. You may need intravenous fluids. 

This article originally appeared on Prevention.com