(CNN) Pilots are prohibited within two days of flying from experimenting with two yet unproven medications to prevent coronavirus infection, the Federal Aviation Administration has determined.

"Use of chloroquine or hydroxychloroquine to prevent coronavirus infection is disqualifying while on the medication and for 48 hours after the last dose before reporting for flight or other safety related duties," a new FAA directive says.

The text was shared with CNN by the Allied Pilots Association, which represents pilots at American Airlines. The directive was signed by Dr. Penny Giovanetti, the director of the Medical Specialties Division within the Office of Aerospace Medicine.

President Donald Trump has touted the medications, chloroquine and hydroxychloroquine, as potentially efficacious against the coronavirus.

But medical experts have warned the early indications are not firm evidence the medications can prevent infection and that there are "potential serious implications" to taking either preventatively.

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