Dexamethasone is a powerful steroid that was reported on earlier this summer.
In a preliminary study, the steroid showed it can improve the chances for survival for patients battling COVID-19, but it's said to be beneficial for patients with severe infection. That includes patients on ventilators or anyone who requires oxygen.
It wasn't found to be helpful for patients with mild illness and could potentially be harmful to them.
- RELATED: Trump says he's leaving hospital for White House, feels good after 3 days of treatment for COVID-19
Dr. John Zurlo, an infectious disease expert at Jefferson University Hospital, said that's what tipped him off.
"Because if you recall, for that news conference, his physician was a little not forthcoming as to whether his blood oxygen level was low, but if he had been taking dexamethasone we have to assume his oxygen was low. We wouldn't give it if his oxygen was normal," he said. "We wouldn't want to cause him harm."
There's also the question about potential side effects.
There are many - including fluid retention, weakening the immune system, also mood changes such as euphoria, agitation, trouble sleeping, and trouble thinking.
That's not to say everyone experiences these, but it's possible.