A remedy for all diseases:

Solution (By Examveda Team)

The one word substitution is Panacea.

Narcotics : an addictive drug affecting mood or behaviour, especially an illegal one.
Antiseptic : preventing the growth of disease-causing microorganisms.
Lyric : (of poetry) expressing the writer's emotions, usually briefly and in stanzas or recognized forms.
Panacea : a solution or remedy for all difficulties or diseases.