It gets into your blood, consuming your thoughts and inducing panic attacks if the next fix is not in sight.
On a good day, it might offer a harmless escape from the troubles of the world.
But on a bad, it can turn into a monstrous distraction, rendering you unable to concentrate on work or studies.
The drug is Facebook, and if you fear you may be an addict, now is the time to find out.
Researchers tested a scientific scale on 423 students which measures how hooked users are.
They found women are more at risk of addiction because of the social nature of the site.
The Norwegian team found ambitious types are less likely to become addicted as they take advantage of the site for their own purposes, such as work and networking.
The Bergen Facebook Addiction Scale lets users measure their dependency on the social networking site by answering six basic questions with how closely they reflect their behaviour.
Those who answer 'often' or 'very often' to at least four of the questions are considered addicted.
The scale is based on the same six core elements of addiction used by doctors to identify alcoholics and drug users, the journal Psychological Reports said.
Lead researcher Dr Cecilie Schou Andreassen, of the University of Bergen's Faculty of Psychology, said addiction is more common among younger users.
'We have also found that people who are anxious and socially insecure use Facebook more than those with lower scores on those traits,' she added. She said this could be because anxious people find it easier to communicate through social media than face to face.
And users who are late to go to bed and get up are more likely to be addicted as those with a 'delayed sleep wake rhythm' scored highly, she said.
Dr Andreassen said: 'The use of Facebook has increased rapidly. We are dealing with a subdivision of internet addiction connected to social media.'
To find out if you are addicted to Facebook, answer these questions with how well they match you using the scale of very rarely, rarely, sometimes, often and very often:
* You spend a lot of time thinking about Facebook or plan use of Facebook
* You feel an urge to use Facebook more and more
* You use Facebook in order to forget about personal problems
* You have tried to cut down on using Facebook without success
* You become restless or troubled if you are prohibited from using Facebook
* You use Facebook so much that it has had a negative impact on your job/studies
Answering 'often' to at least four questions means you are considered to be addicted.
- Daily Mail