Paula Knepper has an addiction.

Every 25 minutes, Knepper (sophomore-nuclear engineering) dips into her bag, puckering her lips in anticipation. She cracks open the container in need of a fix.

For the last four years, Knepper has been addicted to lip balm.

"It's almost enjoyable," she said. "It's kind of like an erotic thing. It's very pleasurable."

Knepper began using lip medication when she was in high school, and her habit has become progressively worse. To be sure it is always available, she carries "vats of petroleum jelly" everywhere she goes. And to keep from getting used to one brand, she switches between flavors of Chap Stick and Mary Kay products.

"I'd go psycho if I didn't have it," said Knepper, who spends up to $40 each year on lip medication. "I have to have it. I need it."

Although little evidence exists concerning the addictive quality of chemicals in lip medication or eye drops, individuals may still possess an obsession or compulsion for these items, said Judith Frankel, clinical psychologist.

"It's more of a conditional response," Frankel said. "If someone is conditioned to do something at a certain time, it can become a strong compulsive pattern."

Wendy Sommerfield (junior-civil engineering), who has been using lip medication for more than five years, said her usage is borderline between habit and addiction.

Because she has been using it for so long, Sommerfield will apply the balm to her lips even if it's not necessary.

"It is a habit," said Sommerfield, who applies Carmex or Chap Stick more than 10 times a day. "If I see it out and I don't need it, I'll still put it on."

But if she goes a long period of time without applying any lip balm, her lips may begin to chap and she gets a sensation that leads her to believe she needs the ointment.

A person becomes so involved in satisfying a habitual response that if the compulsive behavior is disrupted, the person may become irritated, disturbed or even panicky, Frankel said.

"It can grip people very strongly," she said, adding the obsession may be related to one's personality.

Knepper, who considers herself a very compulsive person, said her constant use of lip therapy may be related to her personality, but she does not rule out the possibility of addiction.

"I don't think I could ever stop using it," Knepper said. "I've been using it so long."

Before a compulsion can be considered an addiction or a dependency, it must meet certain criteria, such as withdrawal or mood swings, said Lawrence Clayton, a psychologist.

"You have to be careful with your language," Clayton said. "If you intermingle addiction versus habit, then I think you're starting to play word games that confuse the issue."

But even people who become emotional and upset if they cannot continue their cycle of obsession or suffer discomfort when attempting to quit may not necessarily be addicted, Clayton said.

"If they have a strong habit . . . that doesn't necessarily mean they're addicted," Clayton said. "But if those elements (of withdrawal) are there . . . then maybe that habit is reaching some level of addiction.

"If anything could give you enough of a tickle, you could get an addiction to it," Clayton added.