Daniel Johns, the former frontman of defunct rock band Silverchair, has been charged with high-range drink driving after a head-on crash north of Newcastle.

The crash happened at about 10:30pm on Wednesday, authorities said, shortly after the 42-year-old left a petrol station.

Police alleged Johns was heading north in his SUV when it crossed to the wrong side of the Pacific Highway at North Arm Cove and collided with a van travelling in the opposite direction.

Both vehicles ended up on a nearby nature strip.

"The driver of the van, a 51-year-old man, and a 55-year-old female passenger were treated at the scene," police said.

Johns was breath-tested at the scene and allegedly returned a positive result.

A second test at Raymond Terrace police station allegedly returned a reading of 0.157.

Johns was charged last night.

Panic attacks and self-medication

Within hours of leaving the police station, Johns took to Instagram to say he would check himself into rehab.

"As you know my mental health is a work in progress," he said.

"Over the last week I began to experience panic attacks.

"Last night I got lost while driving and was in an accident.

"I am OK — everyone's OK.

"Alongside my therapy I have been self-medicating with alcohol to deal with my PTSD, anxiety and depression.

"I know this is not sustainable or healthy.

"Appreciate your love and support."

In recent months Johns said on a podcast that his time in Silverchair haunted him.

He is expected to face Raymond Terrace Local Court on April 11.