Rory McIlroy admits he is "paranoid" about the possibility of failing a drugs test in the wake of Matt Every receiving a three-month ban.
Every was suspended from the PGA Tour for violating its drug policy, even though the 35-year-old said that the ban was for cannabis, for which he claims to have a prescription on medical grounds.
While cannabis is prohibited, the World Anti-Doping Agency dropped the cannabis compound CBD from its list of banned substances last year, although the PGA Tour is warning players to use CBD "at their own risk" as some products may contain THC, which is still prohibited.
Two-time Masters champion Bubba Watson signed a partnership with a CBD company earlier this year – it is said to reduce anxiety, inflammation, sleeplessness and chronic pain – but McIlroy appears unlikely to follow suit any time soon.
"I'm very aware of the banned substance list," he told a pre-tournament press conference ahead of the inaugural Zozo Championship in Japan.
"I'm very careful with what I put into my body and I couldn't tell you if CBD oil is good for golfers because I've never tried it.
"It's tough because I take a very strong stance on performance-enhancing drugs or banned substances. I wouldn't be comfortable taking CBD oil. I would be too paranoid that there would be THC in it and then that obviously could lead to a positive test.
"I am the most conservative (person) on everything. I try not to take anything in terms of pills to help in any way. I'm even scared to take painkillers sometimes, like an Advil, I would rather just not."
McIlroy starts his 2019-2020 PGA Tour season this week at Narashino Country Club and plans to repeat the US-centric schedule he employed this year.
The world number two won the Players Championship, Canadian Open and Tour Championship on his way to ending the season as FedEx Cup champion before switching his focus towards the European Tour.
"I think I definitely realised how travel affects me, and not just crossing time zones, but the effect that has on you not just the first week but the few weeks after that," McIlroy said.
"I feel like I performed my best all the way through the season for the most part and I definitely haven't travelled as much this year as I have done in the past, especially bouncing back and forth across the Atlantic.
"That's something that I'm going to try to replicate going forward. I'll start my season in the US and I'm going to play the Irish Open next year, which is at the end of May. I'll go back for that, but that's the only scenario where I'll go back until before The Open Championship.
"That gives me a solid sort of six months in the States where I'm not having to travel a bunch and I think that helped how I performed last season."
