Morphine is one of the strongest and most effective of painkillers, but in the 1800s this effect could come at a cost. In colonial New Zealand, morphine (and its close relative opium) were some of the only medications available which actually worked, rapidly relieving pain. However, this relief came with side effects - morphine was extremely addictive, and after some time using the drug the effects weakened, leading to higher and higher dosages. Morphine became particularly well used after the invention of the hypodermic needle in 1857.