Mubarak Bala, who was born a Muslim, claims he was placed in a psychiatric ward for identifying himself as an atheist in Nigeria on June 13.
The Associated Press reports that Bala smuggled a phone into the hospital, and texted and tweeted from inside a bathroom.
Bala tweeted last Friday that his family assaulted him and forcibly injected him with a sedative.
"My neck still hurts from the stranglehold of my father, and the beat(ing) of uncles dislocated my finger and arm," said the tweet.
Bala, who holds a degree in chemical engineering, told the International Humanist and Ethical Union via text that he's been been prescribed drugs and injections at the Aminu Kano Teaching Hospital.
“If I am helpless and discharged home, they could fake something like my suicide, to rid themselves of the scum, they have been threatening such, ever since I declared openly I’m an ex-Muslim,” wrote Bala.
According to The Independent, Bala is allegedly being held on the grounds of a “personality change” because his family told a doctor that he claimed to be a “governor” and other "trivial lies."
Vice.com notes that Bala claims other patients at the hospital have threatened his life because he has “insulted Islam and the prophet."
Bala's lawyer said in a statement: “Kano is a Sharia state and there are many similar cases occurring, where people are forcefully oppressed just because of their beliefs or for conservative religious reasons, or for the ‘honor’ of their family.”
Bala's lawyer and his supporters have started an online campaign with the hashtag #FreeMubarak.