If you are expecting to have your Aunt Flo in town, the dot at the end of the sentence, the monthly visitor (I enjoy rehashing phrases from middle school), your period (GASP!) while you are traveling, then I recommend that you plan ahead.
I did not know this before I started earnestly traveling, so I’m writing this to the people who might also not know: pads/tampons are different in every country. I think I expected the brands to be different, but the general design and use to be the same. Not so. Their build and their absorbency vary country to country (sometimes city to city). If you don’t want to deal with the changing varieties as you travel, then bring your own bulk. When I traveled for 5 months straight, I brought about 100 pads, just fyi; that meant I was bringing extra, but I like to be prepared.
Some countries/cities sell cheaper knock-off brands of the Big Names. Sometimes this means that they just feel funny when you wear them, not as comfy. Sometimes this means they’re made with unhealthy materials to keep prices down. This can mean that they’re actually not safe to wear; your body could have funny or dangerous reactions. Just know that pads should not be dirt cheap, no matter what country you’re in. There are also countries/cities/communities/cultures in which the women do not wear pads or tampons; if you are going to be in one of these communities, know that it will be difficult to get the goods you’re used to since the local women have their own methods.
On the other extreme of being too cheap, some pads/tampons are very expensive. Knowing that recognizable brands are more desired, they are sold at extreme prices. Sometimes it’s not worth it to spend your daily meal money on them! There are always emergencies, of course.
There are also places where menstruation is shameful, and not talked about. Sometimes pads are kept behind the counter or in the back room, hidden from view. You may need to ask the person working the counter, or a manager, to grab them for you. Just because you don’t see them on the shelves doesn’t necessarily mean the store doesn’t have them. Research the country’s sale of pads before you go, in case the thought of asking a cashier to grab pads for you is embarrassing — but also so you can be respectful in the way you ask.
Also, try not to confuse pads with adult diapers. I did, because I couldn’t read the writing on the bag. Just saying, it can happen.
Also, ibuprofen isn’t a common drug in some countries, or is very expensive, or is only allowed to be sold in very small sizes, so bring your own stash* for the aches and pains.
If you are entering a country or doing the type of travel where you know it will be difficult to wash up, I recommend baby wipes, especially the kind that dissolve, are biodegradable, or can be flushed.
(*Also research if the drug is illegal to bring into a country, instead of buying inside the country.)
TL;DR: Periods happen. Be prepared! Generally bring your own stash of pads/tampons/medicine. Some countries don’t sell them/use cheaper material/sell them at exorbitant prices/keep them hidden. Baby/body wipes are great.