Morphine is an analgesic and hypnotic, relieving pain and producing deep sleep. As contrasted with opium it differs in being less astringent and constipating.
Thus most salts of iron are distinctly constipating, and are best used in combination with a purgative.
constipates, a medicine prescribed for a separate condition may have constipating side effects.
Iron in the intestine causes an astringent or constipating effect.