Avoid coffee before your asthma tests.
Keep your coffee habits in mind if you are getting a lung function test for asthma.
Caffeine in coffee can serve as a bronchodilator, and a review of medical studies showed that it provided small improvements in airway function for up to four hours.
Because caffeine can affect your breathing for up to four hours, you should avoid caffeine for that long before a test to make sure you’re getting accurate results.
Talk to your doctor about how caffeine or other factors may impact your test results when you schedule your tests and appointments.