Alex's mother, Karen Echols, became outraged when the Dumb and Dumber actor shared a photo of her 14-year-old on Twitter on Tuesday while voicing his opposition to a new California law requiring vaccines for all schoolchildren.
The 53-year-old movie star, who lives in California, used several images of distressed-looking children while trying to illustrate his beliefs that mandatory vaccines result in the poisoning of children.
Carrey also called California Gov. Jerry Brown a "corporate fascist" for signing the new bill into law.
But Echols, surprised over Carrey's tweets, called the actor's actions "irresponsible," and said her son's autism was caused by a genetic disorder, not by vaccinations, which "Alex safely received," she wrote.
After she demanded Carrey delete the photo, it was removed and Carey posted this message Thursday night:
Despite erroneously thrusting their son to the centre of the contentious anti-vax and pro-vax debate, Karen Echols accepted the actor's apology and asked him to use his voice for her cause instead.
Despite reams of scientific research to the contrary, Carrey, and his former partner, Jenny McCarthy, have been vocal about an alleged link between childhood vaccination and autism.
McCarthy, a former Playboy Playmate, has also blamed her son's autism on vaccinations.
In his most recent Twitter tirade, Carrey insists he is not anti-vaccine, but "anti-thimerosal" and "anti-mercury," referring to preservatives used in some vaccines.
The U.S. Centres for Disease Control and Prevention says that with the exception of some influenza vaccines, "thimerosal is not used as a preservative in routinely recommended childhood vaccines."
It also says there is "no convincing evidence of harm caused by the low doses of thimerosal in vaccines," except for minor redness at the injection site.