The 56-year-old actor told fans in a Facebook post Tuesday that Douglas wrote him a "nice note" after suggesting Kilmer has oral cancer.
"Michael Douglas wrote me a nice note apologizing for suggesting to the press overseas, I 'wasn't doing too well...' and was grateful to hear I am doing well. He's a classy guy," he wrote.
Douglas, who himself beat stage 4 oral cancer, was at a Q&A in London in late October when he commented on Kilmer's health. The actors co-starred in the 1996 movie The Ghost in the Darkness.
"Val was a wonderful guy who is dealing with exactly what I had, and things don't look too good for him. My prayers are with him," Douglas said. "That's why you haven't heard too much from Val lately."
Kilmer denied he has cancer in a Facebook post after Douglas' remarks went viral. The actor told fans Douglas was "misinformed" and that he and and his former co-star hadn't spoken in nearly two years.
"The last time I spoke to him was almost two years ago when I asked him for a referral for a specialist to get a diagnosis for a lump in my throat," he wrote. "I have no cancer whatsoever."
"I hope this puts to rest any further concerns about my health. Whatever led Michael Douglas to speculate about my health, he's a loving and devoted friend to a privileged group of talent people around the world, and I'm sure he meant no harm," the star said.