The patchwork of rules in the United States makes absolute legality an issue. And you need to be extra careful in other countries.

CBD, or cannabidiol, is the darling of aches-and-pains relief. Forbes deemed its growth “explosive,” noting it is expected to become a $5 billion industry this year. It is said to reduce inflammation and help with anxiety, among its other properties.

There is confusion about what CBD really is. “While CBD is an essential component of medical marijuana, it is derived directly from the hemp plant, which is a cousin of the marijuana plant,” Dr. Peter Grinspoon writes in Harvard Health Publishing of Harvard Medical School. “While CBD is a component of marijuana (one of hundreds), by itself it does not cause a ‘high.’”

The confusion about it also stems in part from a Transportation Security Administration change in policy in May. Previously, it said that CBD was not allowed. The new rule says it is allowed if it contains less that 0.3% THC, the substance in cannabis that provides the high. For more information, it refers fliers to the farm bill of 2018, which was signed into law that December.

Like most legislation, the farm bill is “inside baseball” for many of us. I don’t think many fliers will take the time to understand it, but it is one way to while away long hours at an airport.

When the change was made public, the question arose about how TSA officers would know your product contains less than 0.3% THC. Of course, they could read the label, but imagine the lines that would form while they’re squinting at the contents, assuming it is marked that way. And therein lies some of the problem.

The rest of the problem stems from the variety of laws about hemp and cannabis. They are not consistent from state to state. Just because hemp and cannabis are legal in California doesn’t mean they are legal in other states or countries.

As you evaluate whether you should take CBD with you, consider that:

It is allowed under the change in rules if it meets the qualifications. The TSA is looking for explosives, weapons and other instruments of destruction. It is not looking for personal care products.

Unclear labeling may create an issue. You could run afoul of someone who doesn’t know the law. The possible solution to that, said Minchul An, a doctor of pharmacy who runs buzzn, which sells CBD products: a certificate of analysis, which explains what is contained in your product. Not every CBD product has it, so you may need to request it.

Not everyplace welcomes CBD, due to a patchwork of rules and regulations across the United States.

“Unfortunately, there are still some nuances on whether it’s advisable to fly with CBD, varying most widely state by state,” said Travis Rexroad, director of public relations for Weedmaps, which chronicles the changing state, federal and international laws on CBD and cannabis. “Reason being … that, although there has been movement at the federal level to legalize hemp-derived CBD, certain states hold stricter laws that could mean consequences for those traveling with CBD,” he wrote in an email.

Case in point: A 69-year-old woman was arrested in April at Disney World in Florida for carrying CBD oil in her purse, which was searched. She was detained for 15 hours, according to NBC Miami, for having something her doctor had recommended for arthritis. Instead of a new pair of mouse ears, she ended up with an arrest record, a gift that keeps on giving. The charges have since been dropped, ClickOrlando.com reported.

CBD “is unlike most consumer products,” said William Garvin, co-head of the cannabis group at Buchanan Ingersoll & Rooney, a law firm whose website notes that it is “supporting the cannabis industry as it expands nationwide.”

“It’s OK to drink a Diet Coke in Missouri and drive to Montana with it,” he said. That’s not always the case with CBD, because of conflicting laws.

The answer to this conundrum is that there is no clear-cut answer. Neither Garvin nor An would travel with it because of the risk, however slight. Your product could be confiscated — and some of this stuff is expensive. Or you could be held and miss your flight. Or you could be, like the theme-park-goer in Florida, spending part of your holiday at places that are not the happiest on Earth.

As Garvin pointed out, CBD is widely available domestically. You could buy some at your destination.

But, as always, the decision is up to you. It depends on your tolerance for risk and for pain and anxiety, stemming from the absence of your CBD product and the presence of laws that make life more complex than we could ever have imagined.