Recovering from offseason knee surgery, Vonn returned to racing earlier this month and hoped to enter one or two World Cup events in January.
But she suffered a setback last week at a downhill race in France and now her coach says she may have to rest.
"Her knee was swollen again after Val d'Isere," U.S. women's head coach Alex Hoedlmoser told the Associated Press. "She is working with the guys from [her own team] Red Bull and the medical staff to get that under control."
Vonn originally hurt the knee at the world championships last February. Then she partially tore a repaired ligament during training in November.
She competed at a World Cup event in Canada in early December, finishing 11th in one of two downhills and fifth in the super-G.