I'm usually an advocate in traveling light and buying what you need when you arrive, but there's an aspect to solo female travel that I always want to be prepared for - keeping the reproductive organs happy and healthy.
These tips depend largely on where you're going, but for the most part, when it comes to girly parts, I say you can never be too prepared. This post isn't for the squeamish, as I'm going to talk frankly here, but as a woman, you should put some thought into at least some of my tips to do the best for your health and sanity while traveling.
If you have moral issues concerning emergency contraception, please skip the next paragraph. However, I put this point first because I feel it is a very important consideration to take and not everyone thinks of it.
1) Before you leave, consider getting a prescription filled for Plan B - the "morning after pill" (or other emergency contraceptive).
The laws concerning this pill at your destination may not be the same as where you live now. Also, prescriptions are always cheaper to get at home. Keep in mind that those pills may be illegal at your destination. I suggest bringing emergency contraceptive in the unfortunate event that you are raped, or perhaps the condom breaks or you forgot your diaphragm -whatever it is goes wrong. It will be one less stress to think about during your trip and after your return.
2) Also consider getting a prescription of fluconazole, which is a single dose antifungal pill. In other words, it kills a nasty yeast infection quickly and easily - without messy creams or suppositories. If you can't get your hands on that (or it simply is contraindicated for you) you could just bring a one-day over the counter treatment with you. Once again, though I'm all about adventure, sometimes it's best to stick to what you know works. You don't want to spend your whole vacation wandering around, looking for a pharmacy, then looking for a yeast infection cure in some other language. Also keep in mind that the quality of products in some other countries can be lower (cheaper or toxic ingredients, improper storage, or just expired).
3) Bring your own contraception!
I can't stress this enough. Even if you "don't think anything will happen", you might be surprised by who you meet while traveling and how the rules you usually follow might slide a bit. Do not assume condoms are easy to find in other countries. Do not trust the condoms of your partner - you don't know how they have been stored. Make sure you store yours well (in a cool, dry place, not a pant pocket) and try to keep them in your carry-on (I really don't know if condoms can withstand the cold of an aircraft baggage compartment). I keep mine protected in a cute black pencil case. It's discrete, stops them from getting punctures and is cute enough to walk into a bar with as a purse. (Believe it or not, I also manage to fit a small travel toothbrush and paste, a pair of disposable undies and a panty liner. You never know! Despite all this, I have to admit, I've never managed to hook up with someone in a foreign place, though I know many who have.)
4) Bring your own menstrual gear.
Bring pads, panty liners, tampons, or even better, a reusable cup like the Keeper or the Diva Cup. Bring them even if you aren't expecting your period. The stress of travel and time changes can change your cycle, so you never know. Once again, it's also about not having to waste time wandering around looking for these things when you could be out having fun and exploring.
4b) Probably stating the obvious, but if you take a contraceptive pill, remember to bring it, too! Bring enough for an extra month, just in case you somehow lose your set. Or maybe you'll want to extend your stay.
5) Change your underwear and try to wash daily!
If you don't already, make a habit of it when you travel. It's important to keep things fresh and clean down there, especially in hot, humid climates where there's a lot more bacteria and fungi around. Or you might not have access to clean running water for bathing. If you can't get a shower, try to do a wipe with a face cloth, some soap and clean water.
Just keep in mind that you will probably sweat more while traveling because of things like nervousness and stress, more physical exertion (carrying heavy luggage and walking/hiking) and sitting for long periods in buses, trains and planes.
6) Keep soap samples.
Sometimes you get little single load samples of laundry detergent, right? Keep those for when you travel. They are the perfect size and can be used to do a quick wash of your undies/bras in a hotel sink.
7) Bring disposable undies.
This is more of a "packing light" tip, but I figured I'd add it here. You can get disposable underwear from spas or, in my case, my local Chinatown. They are surprisingly comfortable and breathable. They're fantastic because they come rolled up very small, so they don't take up much space and you can wear them and throw them away after. They're also very light.
Alternatively, you could also buy some cheap undies and throw them away before coming home, but disposables are really the lightest and cheapest out there. I'll admit, they're not very sexy. Maybe that's why I haven't hooked up on my travels....
Comment if you think of others to add and Bon Voyage!