This horrible “vomit” virus is spreading across the US as we speak. Here’s what the experts ask you to know.

Stuffy noses and nagging coughs aren’t the only symptoms of the winter sickness that are popping up now. Also, many people get sick from norovirus, a nasty stomach bug. The highly contagious virus is on the rise in many states across the country.

What is norovirus? “It’s the most common cause of vomiting and diarrhea and actually foodborne illness in the United States,” said Dr. Brintha Vasagar, a family physician in Wisconsin.

These are the two most common symptoms, but sometimes fever, body aches and stomach pains are also reported.

We typically have higher rates of norovirus “from November to April, so we’re still pretty early in the season,” Vasagar added.

Norovirus cases are currently elevated but slightly lower than this time last year, said Dr. Camile Gooden, an internist at NYU Langone-Suffolk Hospital in New York. However, “Recently, there has been an increase in norovirus … we’re seeing more positive tests,” Gooden added. This is due to a new strain of the virus.

The virus spreads easily and in different ways than other winter viruses. Here’s what you need to know:

Norovirus is spread through vomit and fecal particles.

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While common winter illnesses like the flu and COVID-19 are spread through coughs and sneezes, norovirus spreads differently.

“Traditionally, it is [spread through] what we call the fecal-oral route, so stool to mouth, but it’s a pretty resistant virus, so it’s not like licking other people’s poop,” said Dr. Ross Newman, an Oregon pediatrician and medical communicator on social media.

Instead, the contaminated particles end up on people’s hands or the surfaces they touch — and sometimes can even spread through the air, he explained.

If someone who has norovirus doesn’t wash their hands thoroughly after using the bathroom and then uses a towel to dry their hands, that towel can then become a carrier. Then, if an uninfected person uses that towel to dry their hands, they could get the virus.

“It can exist on surfaces for long periods of time … it can be on blankets, gloves, clothing, hair, skin … or it can just be from dirty hands,” Newman added.

Contaminated surfaces can become a “source of spread,” Gooden added, which is how norovirus typically breaks into long-term care settings, day cares and cruise ships — all spaces where people are in close quarters and touch the same doorknobs, tables, light switches and toys.

It can also spread through food.

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Norovirus can also spread through contaminated food, according to Gooden. “If you eat food that hasn’t been washed properly and is contaminated, you could get sick,” Gooden said.

This could be from a sick person preparing the food or even from contaminated raw produce, she said.

“You want to make sure that when you’re eating raw vegetables and raw fruits that they’ve been washed properly because sometimes, even on farms, there could be exposure through irrigation systems to norovirus,” Gooden said.

You don’t need fancy soaps, just washing the products thoroughly with water is enough to kill the virus, Gooden said.

Norovirus can also spread through shellfish that are contaminated with infected water. In this case, cooking the shellfish thoroughly can kill the virus, according to Vasagar.

Hand sanitizer does not kill norovirus, making proper hand washing crucial for prevention.

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“The best way to protect yourself is to wash your hands thoroughly — and you need to use soap and water. You can’t necessarily rely on hand sanitizers, especially if you’ve touched contaminated surfaces or come into contact with someone who is sick with norovirus,” Gooden said.

A quick hand rinse is not enough; use hot water and soap and wash your hands for “the full Happy Birthday song, twice,” Vasagar pointed out. “Most people don’t wash their hands long enough to be really effective.”

Beyond handwashing, disinfecting surfaces with bleach-based cleaners and washing bed linens frequently can kill the virus, Vasagar noted. This is especially important if someone in your household is sick.

“The spread is … so contagious that you’ll have to work hard to make sure everyone else in the family doesn’t get it,” Vasagar said.

If you get sick, stay home, hydrate, and monitor for severe symptoms.

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“Vomiting associated with norovirus is generally short-lived, 24 to 48 hours, but diarrhea can last for two weeks,” Newman said.

People are most contagious in the first day or two after symptoms start, but they can shed the virus for weeks after that, Newman added.

If you get sick, stay home (and keep sick kids at home) if you can, all three experts told HuffPost. Also watch out for dehydration, which is “the biggest concern with complications from most stomach bugs,” Newman said.

“You lose a lot of fluid with vomiting, a lot of fluid with diarrhea,” Vasagar said. Signs of dehydration include decreased urination, dizziness, dry mouth, confusion and fatigue. If you notice any of these symptoms, see a doctor.

To combat dehydration, drink plenty of fluids, whether it’s water, tea, Gatorade or soup, Gooden noted. Even if you vomit, you should still drink small amounts of fluids.

“It’s very important to monitor for any development of severe symptoms,” Gooden said. “If your symptoms continue beyond 72 hours, that’s usually a time when I would advise seeing your doctor.”

If you have a fever, severe abdominal pain or have blood in your stool, you should seek medical attention, Gooden added.

This article originally appeared on HuffPost.

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