Bullets. The N.E.D. gives an instance, ab. 1626, of pills in the same sense.
1803. Instead of boxing and bruising together, like sturdy Englishmen of the lower classes; or whipping one another through the lungs, with swords, or mutually injecting leaden pills, as has been common among the more polite and fashionable people.The Balance, March 1, p. 65/2. (Italics in the original.)