Reports in Saudi Arabia were confirmed by Ghaly's agent, revealing that the Nassr midfielder tested positive for a banned substance.
"Nassr received a notification from the Saudi FA Disciplinary Committee that Ghaly had tested positive for a banned substance," agent Nader Shwaki told FilGoal.com.
"Another sample of Ghaly's blood will be examined this week as the club wait to know the nature of the substance.
"There must be something wrong because Hossam is a professional who is fully aware of the gravity of using banned substances."
Ghaly will be called for an investigation by the committee on Saturday to provide an explanation for the substances he's been taking.
Earlier this week, Wehda forward Alaa Al-Kweikbi was hit by a one-year ban by the Saudi football governing body.