Warning: Facebook Can Be Bad for Your Health

Especially if you're keeping up with your ex-girlfriend.

Beware unhappy asthmatics: Italian doctors warn that Facebook could trigger an attack in some susceptible users.

Gennaro D'Amato and colleagues treated an 18-year-old man whose asthma attacks were apparently sparked by logging into Facebook and seeing how many men his ex-girlfriend had friended.

The man had been taking two inhaled steroid drugs several times a day to control his asthma. But when his girlfriend dumped him - and worse, unfriended him on Facebook - his condition deteriorated.

Using a new nickname, the man re-friended his ex-girlfriend on the social networking site. But the stress of seeing her photo on Facebook linked to so many new male friends was too much.

"The sight of this seemed to induce (shortness of breath), which happened repeatedly on the patient accessing her profile," wrote D'Amato of the High Specialty Hospital A Cardarelli in Naples, Italy and colleagues. Their letter was published Friday in the medical journal Lancet.

The man's worried mother measured his breathing patterns before and after his Facebook activity and found a 20 percent difference. After consulting a psychiatrist, the man decided not to log into Facebook any more. That stopped the asthma attacks. D'Amato and colleagues say social networks could cause psychological stress and trigger attacks in depressed asthmatics.