'Full House' star Dave Coulier undergoes chemo treatment as he battles 'very aggressive' cancer

"Putting a positive spin and sending love to all of you who are battling and going through chemo," Coulier shared on his Instagram Story, Friday. "And remember to laugh."

Coulier is seen at a medical facility, with an intravenous line coming out of his shirt. The comedian flashed a smile and posed with a thumbs up as he wore a backward baseball cap. 

Chemotherapy is a drug treatment that uses powerful chemicals to kill fast-growing cells in your body, according to the Mayo Clinic. Chemo is most often used to treat cancer, since cancer cells grow and multiply much more quickly than most cells in the body.

Coulier's health update comes two days after he was diagnosed with a "very aggressive" cancer.

The comedian shared he was diagnosed in October after he suffered from an upper respiratory infection caused by major swelling in his lymph nodes.

"Three days later, my doctors called me back, and they said, 'We wish we had better news for you, but you have non-Hodgkin's lymphoma, and it's called B cell, and it's very aggressive,'" he told People.

"I went from, I got a little bit of a head cold to I have cancer, and it was pretty overwhelming," he added. "This has been a really fast roller-coaster ride of a journey." 

"The first thing I said to them was, 'Wait a minute - cancer?'" Coulier shared on the "Today" show. "(I was) feeling like I got punched in the stomach because it never happens to you. You always hear about it happening to someone else."

"My brother from day 1. Love you @dcoulier and I'll be by your side through it all," he wrote in his caption with a carousel of photos of the two. 

Coulier shared the news of his devastating diagnosis with his "Full House" castmates through a group message.

"I didn't want them to hear it from someone else, so I sent a text message out," he told People and noted that the response from everyone "was immediate."

"It was just this outpouring of, 'I will be there. You just name the time, and I know you're in great hands with Mel, but what can we do?' It really is overwhelming the love that we have for each other. We've been there for so many years for each other and it's pretty remarkable."

Included in the group text were Stamos, Candace Cameron Bure, Andrea Barber, Jodie Sweetin, Lori Loughlin, Scott Weinger and series creator Jeff Franklin.

The popular show ran for eight seasons, from 1987 to 1995.