Coulier -- who announced last week that he's been diagnosed with stage 3 non-Hodgkin lymphoma -- is defending his former "Full House" co-star after Stamos' wacky attempt to support him online by wearing a bald cap went awry.
"I'm sorry to see a bunch of negative comments as I've just begun my cancer journey," Coulier said in an Instagram statement published Tuesday. "It's our friendship (me and John) and this is how we are handling a very tough time."
The kerfuffle began on Tuesday, when Stamos published a series of goofy but heartfelt photos to Instagram.
In the photos, a "bald" Stamos poses with Coulier and shaves his head in preparation for chemotherapy. In another shot, Stamos and Coulier's wife, Melissa, kiss the top of Coulier's head.
"Nothing like throwing on a bald cap and flexing some Photoshop skills to show some love and solidarity with my bro @dcoulier," Stamos wrote in the caption of his post. "You're handling this with so much strength and positivity -- it's inspiring."
"I know you're going to get through this," Stamos continued. "And I'm proud to stand with you every step of the way. I love you..."
And although plenty of Stamos' followers enjoyed the post, some argued that if Stamos were truly standing in solidarity with Coulier, he would have shaved his head for real.
"What a shallow gesture!" one commenter wrote. "Couldn't even cut your hair off for your friend. And you made sure to post it on Instagram to get those likes too."
"You can just take your cap off and be 'normal' again," another wrote. "When people take this route they actually shave their head. I can't help but feel that you're using Dave's diagnoses as a way to make yourself more likeable."
Others felt these arguments were a stretch. One joked about Stamos' "Full House" character, Uncle Jesse, who took pride in his thick, beautiful locks.
"Uncle Jessie could never cut his hair," they wrote.
In his Instagram post, Coulier wrote that the surprise of seeing Stamos in a bald cap brought him a lot of joy.
"I'm a comedian and humor is what drives me," Coulier wrote. "John knows how to cheer me up and I laughed out loud when he arrived wearing a bald cap -- being a true loving friend and brother."
Coulier added that he lost his sister, mother and niece to cancer, and that humor has frequently been his family's coping mechanism. He said he's proud to have gone public with his diagnosis.
"I have heard from so many people who have been inspired enough by my words and actions to say that they are going to check in with their doctors and get mammograms, a colonoscopy, or a prostate exam," Coulier wrote.