Air travel can be an anxiety-inducing experience for anybody: Are the pilots awake? Is that toddler sitting next to you going to scream through the whole flight? Are the plane's stocks of wine running low? Can you even bring all your prescription medication on board? That last one, at least, is easy to solve, thanks to reasonably clear rules from the Transportation Security Administration and U.S. Customs and Border Protection.

Check It or Carry On?

The Transportation Security Administration allows unlimited amounts of pills or other solid medication in either your carry-on or checked bags, as long as it goes through their screening process. You don't need to declare pills or other solids at the security checkpoint. Liquids are also allowed in reasonable quantities, and they're not subject to the 3.4-ounce limit imposed by the TSA's liquids rule, as long as you declare any excess amounts of liquid medication before you go through the security checkpoint. If you've declared your liquid medications, you don't need to put them in the zip-close bag that you use for other liquids (e.g., toiletries).

Tip

Although the TSA allows you to transport unlimited amounts of pills and reasonable quantities of liquid meds, be prepared for extra scrutiny if you're packing more than 90 days worth of medication, which is considered the standard for a "personal supply." And if you're returning from a trip abroad, you may only be allowed to bring that same personal supply – roughly 90 days – back across the border with you.

How to Package Your Medication

This is the only place where guidelines are somewhat ambiguous: The Transportation Security Administration doesn't require you to have medications in the original prescription bottle, but warns that you should follow each individual state's rules for labeling prescription medication. It's simplest – and safest – to abide by U.S. Customs and Border Protection's requirement to keep prescription medications in their original containers with the prescription labels on them.

If this isn't possible – for example, if your prescription containers are too bulky or you've already thrown them away – bring a copy of your prescription and a letter from your doctor explaining what the medication is and why you need it. If you're traveling abroad, you'll need that prescription and/or doctor's note to bring your medicine back across the U.S. border with you.

Traveling Internationally With Medicine

Speaking of traveling abroad, each country has its own guidelines about which medications are and aren't allowed to cross the border. There are three things you can do to cover all your bases: First, use the original packaging with a prescription printed on it. Second, bring that doctor's note explaining which medications you take and why – and have it translated into the language of your destination country. And finally, give that country's embassy a call ahead of time and ask about any special regulations regarding prescription medication.