At relatively low doses (1–5 g of raw leaves), at which there are mostly stimulant effects, side effects include contracted pupils and blushing; adverse effects related to stimulation include anxiety and agitation, and opioid-related effects like itching, nausea, loss of appetite, and increased urination begin to appear.
[2][9]
At moderate (5 to 15 g of raw leaves) doses and higher, at which opioid effects generally appear, additional adverse effects include
tachycardia (increased stimulant effect) as well as the opioid side effects of constipation, dizziness, hypotension, dry mouth, and sweating.
[2][15]
Frequent use of high doses of kratom may cause tremors, anorexia, weight loss,
seizures, and psychosis.
[2] If frequent users try to stop using kratom, they may experience
withdrawal symptoms including irritability, feelings of distress, nausea, hypertension, insomnia, a runny nose, muscle and joint pain, and diarrhea.
[2][12]
Serious toxicity is relatively rare and generally appears at high doses or when kratom is used with other substances.
[2][9]
In July 2016, the
Centers for Disease Control issued a report stating that between 2010 and 2015, US
poison control centers received 660 reports of exposure to kratom. Medical outcomes associated with kratom exposure were reported as minor (minimal signs or symptoms, which resolved rapidly with no residual disability) for 162 (24.5%) exposures, moderate (non-life-threatening, with no residual disability, but requiring some form of treatment) for 275 (41.7%) exposures, and major (life-threatening signs or symptoms, with some residual disability) for 49 (7.4%) exposures.
[17] One death was reported in a person who was exposed to the medications
paroxetine (an
antidepressant) and
lamotrigine (an
anticonvulsant and
mood stabilizer) in addition to kratom. For 173 (26.2%) exposure calls, no effects were reported, or poison center staff members were unable to follow-up regarding effects.
[17]
Overdoses of kratom are managed similarly to
opioid overdoses, and
naloxone can be considered to treat an overdose that results in a reduced impulse to breathe, despite mixed results for its utility, based on animal models.
[9]
From October 2017 to February 2018 in the United States, 28 people in 20 different states were infected with
salmonella, an
outbreak occurring from the consumption of contaminated pills, powder, tea or unidentified sources of kratom.
[28] An analytical method using
whole genome sequencing applied to samples from the infected people indicated that the salmonella outbreak likely had a common kratom source.
[28]
