hydroxychloroquine
Used it as a malaria prophylactic a long time ago but noticed enough side effects to limit use to no more than 1 month at a time
Some times makes skin thin but in Mr Trumps case that is not a risk as he already has thin skin.
Odd that the chemists and biologists who used to populate this website have said nothing about Vitamin B sometimes recommended as a malaria prophylactic where the risk of catching is low.
Malaria of course is associated with swamp mosquitos, doubtlessly the US mosquito population to have fallen in the past 4 years