The star revealed earlier this month (Jan13) that she was battling a bout of influenza and had been suffering from a 40 degree Celcius (104 degree Fahrenheit) temperature hours before the Golden Globes - and now it appears the illness has become more serious.
Lawrence was named Best Lead Actress for her role in Silver Linings Playbook at the AACTA awards in Los Angeles on Saturday, but her co-star Jacki Weaver picked up the trophy instead.
Revealing her friend's health battle, Weaver told the audience, "I'm going to receive this on her behalf. Poor Jen is really sick. She really is sick. She has pneumonia."
Producer Bruce Cohen revealed that Lawrence hoped to attend the Screen Actors Guild Awards on Sunday (27Jan13) and added to Us Weekly, "With all her appearances, she hasn't gotten enough bed rest."
Silver Linings Playbook was a big winner at the AACTA ceremony - it was named Best Film, and it also bagged the Best Direction honour for David O. Russell. Robert De Niro and Weaver took home the honours for Best Supporting Actor and Actress, respectively.
Best Screenplay went to Django Unchained and Oscars favourite Daniel Day-Lewis added another award to his list with the Best Lead Actor prize for his portrayal of late U.S. president Abraham Lincoln in Lincoln.