Arnica montana, sometimes called mountain daisy or leopard's or wolf's bane is a homeopathic remedy I carry around in my purse all the time. I have had occasion to use it in my travels, even close to home.
Arnica is usually used in cases where someone has been injured and is bruised from the injury. Some people use it before and after having surgery if the surgery means that there will bruising afterwards. And it can even be used when traveling through different time zones for what is known as "jet lag."
What makes me chuckle about Arnica is that when I first learned about it, I was taught, if someone falls and bruises themselves, then gets up and says, "I'm fine!" then you know that Arnica is called for. They also (who's they?) have Arnica cream and gel, which I have used when I've fallen on my bike, and the bruise still hurts when I get home. And of course, after I fall I usually say, "I'm ok, don't worry about me!"
As I have said before, each person is different, so what may help one person may not help another. Arnica can be found at almost any health food store in the United States, and hopefully you or anyone you know will not fall, but if you do, and if you bruise, and if you say, "I'm fine!" then you can give Arnica a try.
[Should you have chronic issues, do not attempt to treat yourself.]