The signs and symptoms of acute beryllium pneumonitis usually resolve over several weeks to months, but may be fatal in 10 percent of cases, and about 15–20% of cases may progress to chronic beryllium disease.
Acute beryllium poisoning approximately doubles the risk of lung cancer. The mechanism by which beryllium is carcinogenic is unclear, but may be due to ionic beryllium binding to nucleic acids; it is not mutagenic.