Megan never saw the addiction coming.

When the 22-year-old grocery store worker began smoking synthetic marijuana 18 months ago, it was a way for her and her husband to get high without having to worry about getting arrested.

At the time, the substance �'' which is also known as fake weed or by the more popular brands K2 and Spice �'' was legal and readily available at convenience stores throughout the area. Many still carry it despite new laws that ban it.

Resembling marijuana but often marketed as potpourri or incense in harmless-looking celophane packages adorned with cartoon characters like Scooby Doo and SpongeBob SquarePants, synthetic marijuana sells for between $4 and $20.

Like so many users, Megan mistakenly assumed it was a safe alternative to marijuana.

But last week, Megan, who didn't want her last name used for fear of losing her job, admitted she was hooked and was trying to kick her habit. It was a struggle. She had gone less than a day without smoking anything and already was trembling and crying.

"I get the shakes, really hot. I can't focus on anything," she said sitting in the sparse living room of her home. "When I get home �'' from work, the first thing I think about is smoking.

"I thought it was a safe alternative, so I jumped on the train," she said. Her husband works at the trailer park where they live. He also smokes K2.

"My husband and I work very hard. We're not bad people," she said, "We never figured we would have it this bad."

Synthetic marijuana �'' technically, synthetic cannabinoid �'' has proven to be stubbornly addictive to users like Megan but has also stubbornly defied the efforts of law enforcement and lawmakers nationwide to ban it from store shelves.

Experts say that as soon as lawmakers outlaw the substance, its manufacturers tweak its chemical composition, creating a new substance that has the same mind-altering effects.

In March, the Florida Legislature outlawed the latest version of the drug, making it a third-degree felony to possess or sell it.

Travis, however, is confident a new, legal version will come out soon. In the meantime, a few area convenience store clerks still sell it to him under the counter.

"And the more you buy from these people, the better the deal you get," he said, tossing a package onto his living room coffee table.

A couple even sell Travis the drug on credit, he says.

"I've gone without toilet paper, but I had a bag of legal weed in this house," he said. "I've gone without food, but I had a bag of legal weed in this house. Instead of making the full payment (for utilities), we'd take the money and buy this stuff."

The stuff Travis and Megan are smoking is an altered form of Tetrahydrocannabinol (THC), the molecule found in marijuana that gives its users their high, said Paul Doering, a distinguished service professor of pharmacy emeritus at the University of Florida College of Pharmacy.

By altering the THC molecule, synthetic marijuana's manufacturers are able to skirt the law and avoid the list of drugs lawmakers have banned.

Doering likens the altering of the complex THC molecule to pruning a hedge, snipping off unneeded parts of the drug and slightly altering others. The result is often a more potent variation of K2.

Dried plant material is sprayed or soaked with the drug.