Analeptic radiation

From Memory Alpha, the free Star Trek reference.

Analeptic radiation is a form of radiation known to be harmful to "a rather pernicious mutagenic pathogen that inhabits the planet Paan Mokar.

In order for Jonathan Archer to visit Paan Mokar, Phlox had to bombard his immune system with analeptic radiation to protect him while he was on the surface. (ENT: "Cease Fire")