Travellers might need to carry or obtain medication on their journey.
Take a copy of your prescription with you. This could be useful if you need to get further supplies, or as evidence that the medication is for your use. If your medical situation is even slightly complicated or unusual, then ask your regular healthcare provider to write a letter that explains it and lists your formal diagnosis. This letter can be useful both in explaining why you have these medications, and also to make it easier to replace your medications if they are lost, stolen, or destroyed at any point during your trip.
Keep your medication in the original boxes or bottles, complete with any pharmacy labels with your name on them. It may also be useful to bring receipts to prove when and where you purchased the drugs.
If possible, take somewhat more than you anticipate needing, in case your trip is unexpectedly extended. Theft of drugs from checked luggage is relatively common. On a short trip, keep all of your medications in your hand luggage. On a longer trip, when you need to carry a larger supply, consider packing some medications in your checked luggage.
The drugs that are readily available vary around the world. Ask your doctor or pharmacy to tell you the generic names of any medication. Your doctor might also suggest an alternative that is more readily available in your destination.
If you need to get more medication when away from home, you may need to get a prescription written by a local doctor. You will probably have to pay for seeing the doctor in addition to the charges for getting the prescription dispensed at a pharmacy. This may be an unpleasant surprise if your medications are normally covered by insurance or a state scheme. Travel insurance is unlikely to pay out if you just run out, but may pay if your medication is stolen with your luggage.
Some countries have harsh restrictions on medications, especially analgesics. Border controls might have harsher limits than the country itself. Opiates and opioids, such as morphine-based preparations, are usual illegal to carry without a proper prescription. In other cases, what's sold over the counter at home is something that requires a prescription at your destination. Check with the foreign embassy to be certain that your medications are okay.