There’s no doubt that medical professionals will have very worrisome patients from time to time. On Wednesday night, HLN’s Dr. Drew welcomed clinical psychiatrist Dr. Dale Archer to discuss what a doctor should do when they feel there is a potentially dangerous situation.

“When you have a doctor/patient relationship as a psychiatrist, then confidentiality is paramount in virtually all cases except for three: child abuse, danger to self, or danger to others,” Dr. Archer said.

He continued, “[If] I got a letter that basically expressed that [a patient] was going to harm people and this is how and when and where, then my first step is to pick up the telephone and call the police. It's very important to understand it's not enough to call the patient and say, ‘Hey, come in and let's talk about this.’ You have a duty to warn, and you have to do it as soon as you have credible evidence that it's a real threat.”

Dr. Drew added, “The horrible part is, though, you kind of sensed that this may be coming and [that patient] won't take their medication. You can't force [the patient] to take medications. That's when our job gets really tough.”

Watch more of Dr. Drew Monday through Thursday on HLN at 9 p.m. ET and follow the show on Facebook and Twitter @DrDrewHLN.