SAN DIEGO -- There was a time when discussions about sexual dysfunction were limited to the bedroom. Viagra brought it to the living room, and now every night, it and two rivals, Levitra and Cialis, battle on the airwaves.

"Well, it's a war, and it's a very expensive war," said Jim Mathews, of the Mathews Evans Advertising.

The competing drug makers are spending $300 million a year on advertisements, trying to tap into the 17 percent of men over 40 who experience erectile dysfunction.

"There's a lot at stake. They're projecting $6 billion in sales in this category by the year 2006, which is not all that far off," Mathews said.

Urologist Dr. Dan Keiller credits the advertisements with prompting men to finally get help for what sometimes turns out to be an underlying condition, like diabetes or high cholesterol.

"I think advertising, even though it has the ploy of selling medications has been wonderful for the community of men and getting us to speak about our health," Keiller said.

Getting that discussion going without being vulgar or generating giggles is a challenge for the drug rivals, each trying to carve out a niche with different themes.

Although the three drugs are competing against each other, they're not starting a price war because each pill still costs about $10. Instead, they are using advertising to try to increase their brand recognition.

Viagra focuses on depicting happy men in their ads. Levitra uses a woman's testimonial and sports star Mike Ditka.

Cialis, which is more subtle and longer-lasting, focuses on the relationship.

The advertisements clearly tap into men's insecurities, according to communication professor Ric Pierson.

"I think it's sort of playing on the construction of masculinity in that somehow your value as a man is sort of tied into your sexual performance," Pierson said.

That's why critics worry that the drugs are used by some just for enhancement. Keiller agreed and runs into that problem on occasion.

"I refuse to give it to a man unless he's willing to talk about it a little bit," Keiller said.

But overwhelmingly, he said, the ads are bringing men to him who have overcome being embarrassed to talk about a once-taboo subject.