(KTRK) -- Former Texas A&M football great Johnny Manziel says a reaction to medication to treat his bipolar disorder sent him to the hospital, adding "it was a scary moment."
Manziel posted to Instagram on Tuesday about recently being admitted to the hospital.
"Unfortunately I had a reaction to an increased dosage in Lithium which I take for my Bipolar disorder. It was a scary moment," Maziel wrote in his Instagram stories, which can be seen by his nearly 2 million followers.
He went on to give his gratitude to hospital staff for "all that they've done in the last 24 hours."
The former Heisman Trophy winner and current pro football free agent is in the midst of an attempted career comeback and image rehabilitation.
Watch Manziel open up on Good Morning America:
After years of carrying on his "Money Manziel" persona, the one-time Aggies quarterback has been working to win a job with an NFL team. Earlier this year, Manziel was working out in College Station at Texas A&M's pre-draft pro day in front of team scouts. He has also made a flirtation to play with the Canadian Football League.
In 2015, Manziel was documented for entering a rehab program.
In February of this year, Manziel said he's taking his comeback seriously while admitting to "self-medicating with alcohol" in the past.