As nouns the difference between antacids and purgative
is that antacids is plural of antacid while purgative is something, such as a substance or medicine, that purges; laxative.
As an adjective purgative is
(capable of) purging.
purgative
English
Adjective
(head)
(capable of) purging
Noun
(
en noun)
something, such as a substance or medicine, that purges; laxative