The actress contracted chikungunya while vacationing in French Polynesia, she revealed on Twitter Saturday.
The virus, which is transmitted by mosquitoes, causes fever and severe joint pain, according to the World Health Organization. There is no treatment, though it is rarely fatal.
"Being sick is no fun," she Tweeted Monday. "But happy new year everyone. Be safe. Love all."
Still, Lohan, 28, seemed in good spirits despite the illness. "In good faith with good people," she captioned a photo on Instagram Monday. "I refuse to let a virus effect my peaceful vacation."
