If you are traveling by plane this Presidents Day weekend, it’s important to take safety precautions to stay healthy. There are a number of unpleasant, and even potentially dangerous, illnesses that can develop on board a plane, says HuffPost, and it’s difficult to deal with them while you’re in the air.

Here are some tips from medical experts on how to deal with in-flight sickness:

• Avoid looking at screens. If you are trying to stave off nausea, try to avoid looking at things that are visual, like your phone or the plane’s television screen, says Dr. Daniel Chandler, a primary care physician at Tufts Medical Center. You’re better off staring at the horizon if you are in a window seat.

• Stay hydrated. Drink water but sip it slowly to avoid nausea or gastrointestinal symptoms. The airplane cabin can be very dehydrating so even if you are not feeling poorly, take extra care to drink plenty of water. This will also help prevent headaches and dizziness, says Chandler.

• Don’t drink alcohol. Alcohol presents a double threat to airplane wellness, say the experts at Northwestern Medicine. Not only does alcohol make it more difficult for cells to absorb oxygen, which will worsen your symptoms, but it also dehydrates your body faster. So, if you are feeling stressed about flying, opt for a non-caffeinated beverage instead of a stiff drink.

• Try to eat a little food. It’s hard to think of eating when you feel queasy, but Chandler suggests snacking on bread or crackers might help fight nausea. Travelers with chronic digestive conditions should pack helpful snacks in their carry-on bags, too.

• Bring your medication. If you have any medical conditions that require medication, make sure you pack extra, especially if you have certain chronic conditions like diabetes or angina. “Having at least seven days of your medicine in your carry-on is a helpful precaution in case your checked luggage gets lost,” notes Dr. Danielle Qing, assistant professor in the Department of Medicine at Mount Sinai.

• Stay seated. Standing or moving around on a plane can exacerbate conditions like vertigo. Stay seated and keep your eyes closed if you feel dizziness coming on.

• Look out for blood clots. Another important issue to keep an eye on, especially on long-distance flights, is the formation of blood clots. “The best defense against blood clots is to move your legs every once in a while,” says Qing. Swelling or pain can be a sign of a blood clot forming, she adds.

• Prepare your immune system. If you catch a cold on a flight it isn’t the result of poor air quality but more likely due to a combination of excessive germs and your body’s compromised ability to deal with them, according to Northwestern University. Hundreds of people have touched the very surfaces you are touching, and everyone is breathing in the same confined space for hours. Pack disposable wipes to sanitize tray tables and the area around your seat, but also make sure that you are getting adequate rest and hydration.

• Avoid flying when sick. Sometimes illness will develop while on board the plane, but if you aren’t feeling well prior to departure, consider postponing your trip or at least checking in with a healthcare professional to protect your own health and that of your fellow passengers. If you are on oxygen for a lung condition, remember that your situation may worsen because of the change in air pressure. Discuss your plans with your doctor. Pay attention to the change of time zones so that you take your medications at the correct intervals, says Chandler.