In some sense, all relationships are codependent, Cannon tells WebMD. "Many people have what I call a 'low-grade infection.' It's always there, but they've been able to adapt to it, work around it. Others have the more aggressive form — they get more and more depressed, develop addictions and relationship problems. They become self-destructive or unduly self-sacrificing. They end up anxious, depressed, and suicidal."

People often get addicted to hope: The hope that the person will change, adds Jeanne McKeon, EdD, a psychologist at the Center for Addictive Medicine at Massachusetts General Hospital in Boston. "Before anything can change, you first have to deal with that addiction to hope. You have to start setting limits. You have to figure out a plan to change things; one that makes sense. Then move through those steps — not allowing any backpedaling."

Origins in Childhood

Childhood is the breeding ground for a vulnerability to codependency. It is typically triggered by an underlying problem in the family — a parent with an addiction to alcohol or drugs, or the "clean addictions" like work, food, religion, gambling, computer games, Cannon explains.

"Even misery can be an addiction," she adds. "People get hooked on their own unhappiness, the victim mentality. They learn to get attention by getting people to feel sorry for them."

Mental illness (like depression), abuse (sexual, physical, and emotional), a chronic illness in the family, divorce — they also set the stage for codependency.

Whatever the scenario is, no one talks about it — that's the unhealthy crux of the problem. "It's a family secret, and it leaves children with powerful feelings that they learn to repress," says Michael McKee, PhD, a psychologist at the Cleveland Clinic. "They learn that it's no use expressing them, because nothing will happen. Everyone is focused on the person with the illness."

Under this veil of secrecy and repressed emotions, the child grows up feeling neglected — emotionally abandoned by the parent, McKee tells WebMD. They don't develop healthy self-esteem and coping skills and have difficulty getting in touch with their own emotions.

"You learn not to trust other people or yourself. You look for fulfillment in pleasing other people, but that never really works — because you don't feel you deserve the approval," he explains.

As an adult, a codependent person has no sense of self, Weiss tells WebMD. "Their whole life is spent in wildly swinging arcs to meet others' expectations. If you're nice to me, I'm a good person. If you look at me funny, I'm a bad person. I don't know who I am. I am incredibly dependent on other people to tell me who I am."

It's a case of arrested development — a combination of immature thinking, dealing, and behaving that generates self-loathing, Cannon says. "That self-loathing is acted out through self-destructive or unduly self-sacrificial behavior in adult years."

To anesthetize the emotional pain, codependent adults try whatever makes them feel better — alcohol, drugs, food, sex, gambling. They become addicted to relationships and will do anything to hold onto them, fearing the emotional abandonment that happened during childhood. They put aside what they want to please the other person, remaining in harmful situations far too long.

In choosing a partner, they gravitate toward what is most familiar — a dysfunctional mate. "We all seek the relationship pattern that we're familiar with, however unhappy it might make us," Cannon explains. "That's why women who leave an abusive relationship gets into a few more, or why someone who was abused as a child gets into an abusive relationship."

Red Flag No. 1: Do you become obsessed with fixing and rescuing needy people?

"Codependents are more oriented to other people's reality than their own," Cannon explains. "They can tell you what everybody else is feeling or needing but have no earthly idea what they want or need. They are the finder, fixer, and Mother Theresa. That is how they see themselves, and where they get their ego fix."

A person's motive for "doing good" indicates whether they are codependent or not, says Cannon. "Are you literally giving for fun and for free — or to get some kind of payoff?" she asks. "If you're codependent, you're trying to be someone's savior to make yourself feel good. You give to them with an expectation of return. After all I've done for you, I get to tell you what to do with your life."

Red Flag No. 2: Are you easily absorbed in the pain and problems of other people?

"Codependent people can be obsessed with the pain and suffering of the other person," Cannon tells WebMD. "That allows them to sacrifice themselves. It's really learned self-defeating behavior."

It's why women in helping professions burn out, McKee adds. "They get super absorbed in the pain of others. They have trouble setting limits in taking in that pain. Some empathy is wonderful. But when you can feel the pain more than the person in pain feels it, it hurts you."

Red Flag No. 3: Are you trying to control someone? Is someone trying to control you?

Neediness is a hallmark of a codependent relationship. One person's happiness depends on having the other person right there — right now. Not letting you hang out with friends, calling frequently to check up on you, having to be with you all the time — these are controlling behaviors, says McKee.

"If you get close to someone else, it's very threatening to them," he explains. "They're calling you all the time when you're away: Do you still love me? Are you still there for me? It's a very unhappy way to live."

Red Flag No. 4: Do you do more than your share — all of the time?

What's the difference between a hard worker and a workaholic? "Motive and consequences," says Cannon. "In those gray areas of addiction — workaholism, housecleaning, perfectionism, religion, computer games — those are the telling signs. Is your family suffering because of what you're doing? Are you suffering?"

"Many codependent people were the favorite child because they did more — took care of the sick parent, got straight A's, cleaned the house," McKee adds. "Now, they feel like a martyr, victimized by doing it all. The martyr has a sense of gratification, but it's not a soul-satisfying gratification."

Red Flag No. 5: Are you always seeking approval and recognition?

Low-self esteem is a mark of codependence. "Shame is the core of the whole thing. Neglected children view themselves as dumb, stupid, worthless, and defective," says Cannon. "It's ingrained into the fabric of their character. It's because the message they got as children was — I don't matter. I'm not important. I'm not worth taking care of."

As an adult, a codependent person judges themselves harshly, says McKee. "When they get recognition, they are embarrassed. They have difficulty asking others to meet their needs. They don't believe they are worthwhile or lovable."

There is no strong sense of self, McKee tells WebMD. "Ask them who they are, and men will give their job title. Women will say I'm a wife, partner, daughter, mother — they define themselves in terms of relationships. A healthy person would say, 'I'm an independent and adventurous person.' There's nothing wrong with being proud of your job or relationships, but a healthy person should be able to identify characteristics beyond that."

Red Flag No. 6: Would you do anything to hold on to a relationship? Do you fear being abandoned?

During childhood, the codependent person felt abandoned by a parent, so they learn to fear it, McKee explains. "They are not really good at bonding. They don't know how to bond in a constructive way that has a healthy dependency between two independent people. They don't feel able to express their own feelings, express a difference in opinion, so bonding never quite works."

People who put up with abuse "are usually bright, attractive, intelligent women," he tells WebMD. "The abuse ranges from emotional to sexual and physical abuse. Why do they go back? Because they feel so terrible about themselves… that nobody else would want them."

Pulling Out of a Codependent Relationship

Like any problem, you need to understand what's at the root, says David A Baron, MSEd, DO, chairman of psychiatry at Temple University Health System.

"Often the enabler feels guilty about the situation, Baron tells WebMD. "They care about the other individual in the relationship; [they] know there is a good side to this person. They're hoping against hope that they can go back to the good times — even when it's blatantly obvious nothing will change."

At some point, they have to wake up and smell the coffee, he says. "They have to get beyond their emotions and look at the history of behavior. This has been a pattern. When you can get past the emotions and examine facts, write them down. Do a little timeline or a score card of bad behavior."

Getting in touch with your anger is critical to recovery, says McKeon. "Guilt is vague and inactive and tends to paralyze you. It is the opposite of anger — and in reality, you are really very angry. You may be angry about old issues from your childhood. Anger will demand a response. Anger will make you active."

Getting professional counseling from a mental health worker, psychologist, or family physician can give you the strength to break away from a codependent relationship, Baron says. Twelve-step programs also help and are free.

"Group therapy often works well," says McKee. "You meet people who can be your Indian guides; who model healthy behaviors for you, who point out what you're doing. It can be more acceptable coming from them than from an authority figure because they've been there."

Short-term family therapy is also effective, McKeon adds. "You don't have to get into years of analysis. You're looking at the family, how it's affecting everybody, what the game plan should be. Getting everybody together equalizes things so no one feels blamed."