TMZ has learned that actress Mischa Barton was rushed to the hospital last night after suffering an adverse reaction to medication.

Sources tell TMZ that the former “OC” star was at a friend’s Memorial Day BBQ enjoying a few holiday cocktails when she began to feel extremely ill. Mischa, who has been quite sick with bronchitis since traveling to Cannes, London and Paris the past several weeks, apparently didn’t get the memo — you can’t drink alcohol while taking antibiotics!

The 21-year-old celeb was rushed to an undisclosed medical facility in Los Angeles, where we are told she is “resting comfortably.”

A rep for Barton tells TMZ that the starlet is with family and “feeling much better.”