Your bags are packed. You’re checking and double-checking that you’ve got everything. Do you have enough of your blood pressure medication? Or allergy pills? Or insulin?

Whatever medications you take, your trip won’t be much fun if you run out, or your medications are lost, or you get sick because you didn’t take them at the right times. Here’s how to make sure you have your medications when you need them while you’re traveling:

Bring More Than Enough Medication

Bring extra supply of your medications with you in case you lose or spill some. This will also ensure that you have enough medication with you if your trip is lengthened for some reason. Some medications in your country are not available in other countries. It may be difficult to get a prescription filled away from home.

Bring the Prescription

If you do need to get more medication while you’re traveling, you’ll have a much easier time if you have the prescription.

Bring a Note from Your Doctor

If you take prescription medications, carry a letter from your doctor with you explaining your condition, what medication you take, and the dosage. Make sure you have this information for all the drugs you take. With increased airport security measures, you may find that security officers are more concerned about what you’ve got in your bag. This can be of particular concern if you must carry medical equipment, such as syringes to inject your medication.

Plan for Time Zone Changes

Talk to your doctor about how you’ll adjust your medication schedule to account for changing time zones. When traveling overseas, you can lose or gain as much as a day, so you’ll need to carefully time your medication doses so you don’t miss any.

Pack Medications in a Carry-on Bag

Keep your medications with you while you’re traveling. You may need to take your medications while you’re in transit—on the airplane, in the airport, on the bus or train. Even if you’re traveling by car, keep medications in the car with you. The trunk of the car and the baggage areas of planes and buses are not temperature controlled, and some medications should not be exposed to very hot and very cold temperatures. Plus, if your luggage gets lost, you could be without it for days.

Bring Your Own Water (and Food If Necessary)

Do not drink tap water if you are traveling in certain regions of the world. Instead bring your own or buy bottled water. And if you need to take your medication with food, bring your own snacks. Don’t rely on stores or restaurants to be available or airlines to serve food.