Matthew McConaughey says that he consulted three doctors because he was so worried about the rise of HIV when he was growing up in Texas in the 1980s.
The 44-year-old, who is nominated for an Oscar for his portrayal of HIV patient Ron Woodroof in real-life story Dallas Buyers Club, told RTÉ Ten: "I remember in 1988 I was a senior in college and as a hetrosexual young man becoming sexually active I remembered getting worried and what I clearly remember is talking to three different doctors and saying, `give me some science on this.
"'I'm a hetrosexual man and I'm having . . . I'm not being too loose but give me some percentages, give me something . . . ' and they had three completely different answers about what the risks were so I came away from that being more scared.
"I remember thinking, well I'm gonna go with the guy who said be the most cautious. But nobody knew at the time, the doctors didn't know."
McConaughey also told Ten that he was keen to avoid sentimentalising Woodroof's story in the movie. "This story hasn't been done this way, it hasn't been approached this way. This story couldn't have gone to sentiment especially in the third act but it would have been untrue to the man Ron Woodroof was so you see the anarchy, you see that this is a real guy. This is not a message movie. The message comes out of following this guy's life."
Dallas Buyers Club is released this Friday, February 7.