The company behind Botox is lobbying Congress to make it harder for cosmetics makers to compete with a $100 million-a-year drug it markets to thicken eyelashes.

Allergan Inc., which makes Latisse, a popular mascara-like treatment, wants Congress to pass legislation that would force its competitors to submit their currently unregulated eyelash products for Food and Drug Administration reviews.

Latisse became the only product approved by the FDA to treat people with sparse lashes in 2009. Since then, several smaller companies have started selling less-expensive eyelash enhancers classed as cosmetics. Those products never went through the rigorous study-based regulatory approval process that Allergan faced.

Allergan lobbyists have spent the past few years making the case to the FDA and Congress that those products should be considered drugs. But debate over how to classify such aesthetic treatments has delayed a decision.

The FDA considers any product intended “to treat or alter the structure or function of the body” a drug, agency spokeswoman Shelly Burgess said. She would not say whether the FDA was investigating any of the products that contain similar ingredients to Allergan. “As a policy we do not confirm or deny what we’re investigating,” she said.

Reps. Marsha Blackburn (R-Tenn.) and Loretta Sanchez (D-Calif.), whose district includes part of Orange County, have repeatedly demanded that the FDA investigate Allergan’s competitors. Now Blackburn is considering a legislative solution that could become part of a broader reauthorization of the U.S. drug-approval process.

“FDA maintains that this is a complicated issue; that’s why it has taken so long,” said Mike Reynard, a spokesman for Blackburn. “Even complicated problems need to be addressed, and three years in our opinion is long enough.”

Allergan would like Congress to require all products containing a class of ingredients known as prostaglandin analogs, or PGAs, to be approved and sold as drugs. Latisse’s active ingredient is a PGA.

The FDA has no authority to regulate ingredients or recall cosmetic products, and although it can ban substances deemed dangerous, it rarely does.

“This is a growing problem, not a static problem,” said Damon Burrows, Allergan’s vice president and associate general counsel. “The longer this proliferates, the greater the potential that other companies will try to use PGAs in products that they claim to be cosmetics.”

To make the case, the Irvine, Calif., company beefed up its team of lobbyists this year, hiring two more firms, Thorn Run Partners and Trimpa Group. In 2011 the company paid in-house and contract lobbyists a total of $2.8 million.

It is hard to say exactly how many rival products contain the ingredients. Last spring, the FDA warned at least one company, Lifetech Resources, that it misbranded a similar product called RapidLash that also contained PGAs. Revitalash, another eyelash enhancer made by Athena Cosmetics Inc., also contains a PGA, according to its website. The company did not respond to Roll Call’s request for comment.

Blackburn is considering accommodating Allergan by including its proposal in a reauthorization of the Prescription Drug User Fee Act, a must-pass bill that helps fund the FDA and expires in September.

Latisse costs $90 to $120 for a month’s supply and is not covered by insurance. It is identical to Allergan’s glaucoma drug Lumigan, an eyedrop that spurs eyelash growth as a side effect. Athena’s product, by contrast, costs $150 for a six-month supply.

The issue is likely to remain a top priority for Allergan. The company is currently testing the same compound as a therapy for baldness, a move that, if successful, could open up a $1 billion market, the company said.