Johns has recently been diagnosed with frontal lobe epilepsy after suffering two major seizures over the past three months.

The Newcastle great revealed he experienced attacks every two months since his first seizure while commentating late in 2016.

And while Johns has since been on medication, doctors have upped his dosage following his recent scares in Yamba and New Zealand.

"I had one up in Yamba over Christmas where I actually fell over and smashed my head," Johns said in a tell-all with brother Matthew on Fox League on Sunday.

The former Kangaroos and NSW State of Origin star admitted to initially being rattled by his health scares before reaching out to specialists in Melbourne.

"Because, like everyone, when something goes wrong you google it. And then it comes up with the worst-case scenario," he said.

"But the doctors and professors I'm seeing, they said if you get your medication levels right you can live a normal life."

The 44-year-old said doctors were unsure about the cause of his condition, but suggested his history with concussions may be a factor.

Head knocks have been a serious issue for the NRL in recent years, with the game's lawmakers strengthening its rules around blows to the head.

Former Knights winger James McManus is among a handful of players who have taken legal action over treatment of their concussions.

"(The doctors) can't be sure what caused it. It could be something that popped up later in life," Johns said.

"But they think maybe - and that's maybe - a contributor could be some of the concussions I've had, some of the continual head knocks."

The Newcastle great has been stripped of his driving license, warned not to surf alone and told to slow down his lifestyle.

He attempted to describe the moment he first had a seizure in 2016.

"I was commentating and all of a sudden, something came on in my body where I went into this trance-like state," Johns said.

"I went into this dream, it's hard to describe ... like deja vu. You've seen where you've been before. Everything goes quiet.

"It hit me and then I've come out of it, just sitting in the comm box and obviously I didn't say nothing for a while.

"Then the producer came up and said 'Mate, are you all right?'. I said, 'Yeah, yeah'.

"Later that night I went back to the hotel and straight to bed which is pretty much a first and woke up in the morning with two big puncture marks in my tongue.

"And my tongue had swelled right up."

Australian Associated Press