According to the magazine, the actor's rep says he's "fine," but is still heading to a Los Angeles-area hospital.
Arquette was reportedly driving his Cadillac when he swerved into oncoming traffic while trying to avoid a car that stopped suddenly and hit another car head-on.
In pictures seen on TMZ, Arquette is shown in jeans and a white t-shirt lying in the grass next to the accident scene.
"Remember to wear your seatbelt-wish I was," Arquette tweeted about an hour after the accident was called in to the police. He continued to post updates throughout the rest of the evening. "I got into a car accident but I'm fine. Luckily I have dragon's blood running through my veins... Haha Thank you for all your concern... It was a miracle the woman I hit was uninjured- Thank God!... Refused all pain medication-may the record state- still sober!"
Arquette said he was on the way to catch a plane to Las Vegas to help his friend open The Sugar Factory restaurant when the accident occurred.
Arquette, 39, checked out of rehab for "alcohol and other issues" in January. Last year, he and his wife, Courteney Cox, announced their separation after 11 years of marriage.