Demi Lovato posted a heartfelt tribute on her Instagram Stories after her good friend Thomas died late Tuesday from a suspected overdose.
Lovato has admitted to struggling with substance abuse in the past.
(MORE: Demi Lovato posts bikini pic on Instagram)"Please hold your loved ones tight. Tell them they are special and that you love them," she wrote, sharing a black and white photo of her late friend.
She then cautioned fans that "Addiction is NO joke" and called it a "terrible disease."
The 27-year-old also encouraged fans to watch out for their friends and family.
(MORE: Is there a romance brewing between 'Bachelorette' contestant Mike Johnson and Demi Lovato?)"If you or someone you know is struggling please know it's okay to ask for help," she added.
Lovato suffered a suspected overdose last summer, almost a month after revealing she relapsed after six years of sobriety.
She addressed fans a month later by writing, "What I’ve learned is that this illness is not something that disappears or fades with time. It is something I must continue to overcome and have not done yet."