I have heard that in some countries certain medications that are legal in the US are illegal there. Has anyone had any issues with this going through security or customs in Spain? Where can I find out info on such?
Just because something is not sold over the counter in Spain doesn't mean it is illegal there. Security agents aren't looking for drugs and customs is just a walk-through. The only thing I would be concerned about carrying is medical marijuana, or huge quantities of narcotic painkillers.
Whether or not inspectors in other countries will worry about the kinds of meds and how they are orgainized if a toss up. Personally, I've never had a problem taking meds into other countries for my personal use (and we've had more than 40 international trips) It is the INFORMATION that is important- more in case you have a medical emergency, or need a refill (lost meds, trip extended...) You should have the brand name of the medication (ambien, etc.) and the generic name, and if no generic, a "chemical" name as brand names are not always the same. There are lots of ways to organize your meds. They do NOT have to be in the original containter (except for liquids). If they are not, however, you should have the "pharmacy" information- You can ask your pharmacist to print you an extra label (or use the one they give you that is with the 'side effects" printout).
I also carry an information sheet with the above info AND I also list my Dr's phone #s, pharmacy's #, and emergency contact info as well a list of medical conditions, surgeries /dates. If you become ill while traveling, or need a refill because you lost meds, etc. it could be vital. Feel free to private message me with your email if you want a sample copy of the info sheet. Also, note that liquid meds (they can be more than 3 oz.) should NOT be placed in your 3-1-1 bag, but should be in their own baggie, in original bottle. You MUST declare this to the TSA at departure in the USA. Also if you use a CPAP, nebulizer, etc, these devices must be declared and removed for separate screening. Most airlines don't count these in # of allowed carry-on. But you will want to check with yours.
Drug approvals are country (or region) specific, so something approved here may not be available in other countries, or may not be available in the dosage strength you need. Many recommend keeping prescription drugs in their original containers, and that's certainly the safest approach, but it takes a lot of space. But I've never kept them in the bottles and never had a problem. I put them in tiny zip-lock bags (maybe 2x2 inch) and paste the label from the prescription bottle on the outside of the appropriate bag. Takes almost no space and works fine. I've never had anyone even look at them. Also keep a list of brand name, generic name, dosage strength, and dosing schedule.