It’s a terrible moment of realization when you feel nausea start to build. Saliva floods your mouth, sweat beads on your brow and your heart races.

You take a few deep breaths — a physical reflex designed to protect the lungs from accidentally inhaling vomit — and calculate how quickly you can travel to the nearest restroom or if necessary, a trashcan.

You’re not sure if it was the sushi you ate for lunch or the virus that’s been making the rounds at work. Whatever the cause of your impending puke fit, the chemoreceptor triggers zone (CTZ) located in the fourth ventricle of your brain has taken over. This vomit control center contains a concentrated number of serotonin, dopamine, opioid and acetylcholine receptors, along with “P,” an occasionally prolific neurotransmitter substance that signals your body to blow chunks.

The receptors in the CTZ may be in the brain, but they lie outside the blood-brain barrier. Because of their location, they can be penetrated and stimulated by drugs, medication or other provocations, such as the inner ear, vagus nerve (gag reflex), the enteric nervous system (digestive nerves) and the central nervous system. As a result, the contents of your stomach revolt.

One way to squelch the urge to upchuck is by taking over-the-counter medications (dimenhydrinate or meclizine hydrochloride) designed to prevent motion sickness, as well as prescribed medications (promethazine or prochlorperazine) that directly impact and calm receptors in the CTZ. But that requires you to have them handy, and OTC medications for motion sickness usually take 30 to 60 minutes before they kick in.

For a quick and all-natural approach to vomit prevention, try acupressure. Press on the inside of your wrist with your thumb or fingers. Find the Pericardium (P6) point, located in the groove between the tendons that run from the elbow to the palm. When the P6 is stimulated, it activates the nerve system and signals the brain’s release of neurotransmitters. These neurotransmitters — serotonin, dopamine and endorphins — overpower other chemicals (such as “P”) and may help quell vomiting.

Many people swear by ginger’s nausea-relieving properties, but studies have been inconclusive about the effects. A 2012 randomized, double-blind, placebo-controlled study of 80 women undergoing chemotherapy for breast cancer found those who took powdered ginger experienced less nausea and vomiting. For some, it also works to suck on ginger in hard candy form. So keeping ginger candy on hand might also be useful.

The urge to vomit may be a physical response, but you can try taming it with your mind. Just use your imagination. Instead of embarrassing yourself by vomiting on your shoes (maybe even their shoes), picture yourself chillin’ on a beach. Your mind’s eye could take you anywhere, as long as it helps you escape your current nausea [source: Serani]. If all else fails, continue to calculate those steps to the nearest bathroom. Odds are you’ll need to get there in a hurry.