Kratom (Mitragyna speciosa) is described as being a stimulant at low doses, and narcotic/sedative at higher doses. Dosages can vary greatly depending on the freshness of the leaf and the potency of the particular plant/strain. Fresh or freshly dried leaves are generally considered the most potent, but dried leaves are most common outside of SE Asia. Following are approximate dosages for oral (chewed or tea) dried and transported Kratom leaf in grams (as sold outside SE Asia).

IMPORTANT NOTE: Though there have been four common grades of kratom leaves sold on the commercial market, since 2014 the Enhanced, Super, and Premium grades are the norm. Some companies have used terms like "Organic Commercial Grade" for the least potent (dosages 5-30 grams dried leaf), "Premium" or "Instant Premium" (dosages 2-15 grams), and "Super" (2-8 grams) or "Super Enhanced" (dosages 1-5 grams).

Many vendors do not use these labels for their products and the potencies are not standardized in any way. From 2000 to 2003, kratom sales were usually of plain, commercial grade dried leaf and leaf powder. Since then, the potency of products has increased.

Nausea, dysphoria and vomiting are likely with strong doses, especially in those not already experienced with the effects of kratom. It is important for kratom-tea drinkers to start low with the specific leaf material they have and slowly work the dosage up to avoid unpleasant effects.

A teaspoon of dried leaf is usually between 1.5 and 2.0 grams. 1 milliliter of dried leaf is usually between 0.3 and 0.4 grams.

Tolerance develops with daily or near-daily kratom use in most people. Doses increase as tolerance increases.

According to a report by the National Drugs and Poisons Schedule Committee of Australia, "Poisindex indicates that in adults, a dose of 50 mg of pure mitragynine has produced motor excitement, rombergism [unsteadiness on feet with eyes closed], giddiness and tremors of the face, extremities and tongue."