A baton-wielding patient returned to a hospital to take revenge on a medic who 'hurt him during drug rehab' in Thailand.

Thanongsak Upati, 29, was seen entering Phon Na Kaeo Hospital in Sakhon Nakhon province wearing a helmet and pulling out a baton stick from his backpack on April 1.

The furious ex-patient was shouting for the name of the nurse 'Krittaphat Chunrasri' scaring patients and medics away while security staff tried to catch up with him.

He then found Krittaphat at the emergency room where he hit him several times before staff were able to pull him away and fled the scene.

Shaken nurse Krittaphat said: 'I knew he was angry with me but we were only following proper medical procedure. We did not intend to hurt him.'

The nurse suffered bruises all over his body including a cut on his head following the attack but received treatment in the same facility.

The baton-wielding attacker fled the hospital but was later caught by officers at home. He was taken to the police station and charged with invading government buildings with a weapon, physically assaulting an officer and illegal drug-related charges.

Police said he admitted the attack and will be remanded in custody before being sent to the Sakhon Nakhon Provincial Court for sentencing.