Reported adverse effects.

Common acute effects

Self-reported and clinically-observed acute adverse effects of μ-opioid agonist exposure including 7-OH [1, 5, 8]:

• Nausea and vomiting, especially in opioid-naive users at higher doses
• Constipation (opioid-receptor activity in GI tract)
• Sedation, drowsiness
• Dizziness, vertigo (described colloquially as "the wobbles" in user communities)
• Pruritus (itching)
• Sweating
• Respiratory depression at high doses, especially combined with other CNS depressants

Chronic exposure effects

• Physical dependence and withdrawal syndrome on cessation (covered separately on /AddictionAndWithdrawal)
• Hepatotoxicity — case reports of cholestatic hepatitis associated with kratom use [1, 6]. Whether 7-OH specifically contributes is unclear; most cases describe multi-alkaloid leaf or extract products.
• Cardiotoxicity — emerging case reports including QT-interval prolongation, arrhythmia. Mechanism not well-characterized.
• Weight loss, anorexia — described in chronic high-dose users.
• Cognitive effects — memory complaints in self-report data, though formal cognitive-function studies are limited.

Serious and rare events

• Overdose and fatal overdose — kratom-attributed deaths have been documented but in most cases involved polysubstance exposure (especially other opioids, benzodiazepines, alcohol). FDA post-market data reports rare cases of kratom-only fatal exposure [6].
• Seizures — case reports, mechanism uncertain.
• Neonatal abstinence syndrome in infants born to chronic kratom users.
• Adulteration-related events — products marketed as kratom or 7-OH have been found contaminated with undeclared synthetic opioids, MGM-15, MGM-16, or other pharmaceutical analogs. The FDA has issued multiple warning letters on this [6].

Polysubstance and drug interactions

μ-opioid agonism creates known interaction risk with:

• Other opioids (additive respiratory depression — significant overdose risk)
• Benzodiazepines, alcohol, gabapentin, pregabalin (additive sedation/respiratory depression)
• Serotonergic medications (SSRIs/SNRIs/MAOIs — possible serotonin-syndrome contribution at high doses)
• Strong CYP3A4 inhibitors (potential potentiation of 7-OH exposure)

What's harder to find clean data on

Several gaps remain. The pharmacokinetics of concentrated 7-OH after oral administration in humans have only limited published data. Long-term effects of high-dose concentrated 7-OH (as opposed to leaf-kratom use) are not well-characterized in formal cohort studies. We update this page as research emerges.

References

See our bibliography for the full citation list. If a claim on this page needs a citation we haven't added, email corrections@7oh.org.