In the last few years, gamma hydroxybutyric acid (ghb) has been used increasingly as a party drug; this has led to a marked increase in the number of requests for professional help with the treatment of ghb addiction. Pharmaceutical ghb (sodium oxybate, the sodium-salt of ghb), registered for cataplexia in narcolepsy patients, is used off-label to treat the withdrawal symptoms associated with ghb addiction. Pharmaceutical ghb has a high sodium load. In this report we present the cases of two patients who developed symptomatic hypernatremia following treatment with pharmaceutical ghb and who thereafter needed intensive care for the severe withdrawal symptoms that they experienced.