The rocker has been in and out of rehab for his drink and drugs addiction, without properly kicking his habits, and one particular bad patch nearly put an end to the rockers' touring days.
In the book, Cowan reveals how he took Wood to a prestigious doctor to address his problem prior to one of the band's tours.
"He (the doctor) asked Ronnie how many units of alcohol he consumed on a regular basis. Ronnie totted it up and told him," the Sun quoted him, as saying.
"'Hmm,' said the doctor. 'Not too bad - almost within the acceptable number of units per week.' 'Per week?' said Ronnie. 'What are you talking about? That's my daily intake.'
"His addiction became so severe he could not pass the medical for the 2003 tour and had to spend a month in a clinic in Arizona before he was fit to go touring," he added.