Kratom can take effect within five to ten minutes after ingestion. Effects can be expected to last for five to seven hours, with the effects peaking at about two to four hours. However, mild effects may last even into the next day.
The two most potent alkaloids in kratom have half-lives of 2.5-3.5 hours. That means that it takes about three hours for the concentration of the alkaloid in the body to be reduced by one-half. The active compounds are eliminated through the urine.
Consuming kratom with food may delay the onset of the effects. There are also other ways to enhance extraction of the bioactive alkaloids, or enhance absorption of alkaloids in the small intestine. That is why different modes of consumption (for example, kratom capsules, tablets, or teas) can change the way you experience kratom.