NEW YORK - It is highly unlikely that federal regulators would ever give Pfizer Inc. approval to sell its erectile dysfunction medication Viagra over the counter because of safety risks associated with the drug, analysts said.

Pfizer confirmed Thursday that it routinely evaluates Viagra for a number of options including selling it without a prescription. That followed news reports Wednesday that the company was considering an over-the-counter launch. However, the company declined to provide any details about whether such a move would be taken.

Analysts said it doesn't make sense for Pfizer to pursue that strategy because the chances of regulators approving the drug as an over-the-counter medicine are practically nil.

A major reason is that men who take drugs that contain nitrates, such as nitroglycerin for chest pain, should not take Viagra, because serious complications can occur. A warning notice about that is included on Viagra's label, but doctors also tell patients about the risk, said Jason Napodano, an analyst at Zacks Independent Research.

"You can't trust patients to read the label," Napodano said.

Viagra also has other risks such as sudden vision loss and the potential of causing a four-hour erection.

Jon LeCroy, an analyst with Natexis Bleichroeder Inc., said he didn't think the FDA would take a chance on letting a drug with such risks be sold without a prescription, especially since it is a lifestyle product and not something that treats a disease.

For the nine months ended in September, Viagra sales fell 1 percent to $1. 2 billion. The drug has come under pressure because of competition from Cialis, which is made by Eli Lilly and Co and ICOS Corp., and Levitra, which is marketed by Schering-Plough Corp. and GlaxoSmithKline PLC.

Schering-Plough spokeswoman Julie Lux said the company wouldn't speculate on any future decisions about Levitra. Glaxo and Lilly didn't immediately return calls for comment.