Maybe it depends on what destinations you choose, but I tend to agree with the Prince. OK, so I do tend to go places that aren't so well developed, but even if you CAN get whatever you need, it doesn't mean it's easy, or cheap, or anything other than a disruption in your travel plans.
Sure OTC in London, Amsterdam, Frankfurt, Rio, Tel Aviv, or Paris are probably fine. But why take the chance? I can't imagine traveling without an extra weeks worth of my prescription meds along with a bottle of generic extra strength tums that I get from WalMart. I don't want to waste my TRAVEL time in a pharmacy with my electronic translator trying to figure out if the package I have, written is French, is what I need or not.
Be a boy scout. Don't be afraid, but do be prepared.