What Are the Effects of Kratom on the Body?

Kratom is gaining increasing attention worldwide, yet many people remain uncertain about how it affects the body. From its stimulant and sedative properties to potential long-term health considerations, understanding kratom effects is crucial for both newcomers and experienced users.

While research is still emerging, current studies and observational reports provide insight into how this plant interacts with multiple systems, highlighting potential benefits and risks.

What Is Kratom & How Does It Work?

Mitragyna speciosa is a tropical evergreen tree native to Southeast Asia, belonging to the coffee family (Rubiaceae). It grows in humid, tropical climates across Thailand, Malaysia, Indonesia, and Myanmar. Its leaves contain more than 50 alkaloids, but mitragynine and 7-hydroxymitragynine are considered the most biologically active.¹

These alkaloids interact with multiple receptor systems, including mu- and kappa-opioid receptors, as well as adrenergic and serotonergic pathways, which may explain reports of both energising and calming effects. For background on origins and traditional use, see what kratom is and its origins.

Kratom’s effects come from partially activating opioid receptors. Unlike classical opioids, these alkaloids tend to produce milder sedation, and preclinical work suggests a reduced risk of respiratory depression at common doses.²

Beyond opioid receptors, kratom interacts with adrenergic, serotonergic, and dopaminergic pathways, which may explain its reported effects on mood, cognition, and energy. This broad mechanism distinguishes kratom from single-pathway substances like caffeine or morphine.

How Is Kratom Metabolised?

Once ingested, kratom alkaloids undergo hepatic metabolism, mainly via CYP3A4 enzymes (with CYP2D6/2C19 contributions). Active metabolites contribute to both short-term and longer-lasting effects.³

Peak plasma levels typically occur within 60 minutes, with an elimination half-life of 3–6 hours depending on dose and individual metabolism. Variability in metabolism partly explains why users experience different durations and intensities of effects.

Individual genetic polymorphisms in CYP3A4 and CYP2D6 enzymes can lead to faster or slower metabolism, potentially affecting both the intensity and duration of kratom’s effects, as well as the risk for accumulation with repeated doses.

What Are the Most Common Effects of Kratom on the Body?

The subjective experience of kratom is strongly dose-dependent. Learn what to expect at different dose ranges below. For practical guidance, see how to dose kratom safely.

Low Doses (1–2 g)

• Mild stimulation
• Alertness
• Increased sociability
• Enhanced focus
• Heightened sensory perception

Moderate Doses (2–5 g)

• Balanced energy and relaxation
• Mild euphoria
• Improved mood
• Possible anxiolytic effect (calm confidence without sedation)

High Doses (5–10 g)

• Sedation
• Strong analgesia
• Drowsiness
• Pronounced muscle relaxation
• Potential mild dissociation in sensitive individuals

Strain differences also impact effects. Red-vein kratom is generally associated with sedative effects, green and yellow-vein with balance, and white-vein with stimulation. Harvest time, leaf maturity, and post-harvest processing can alter alkaloid ratios and potency. For vein colors and typical profiles, see different kratom strains explained.

Short-Term Effects of Kratom on the Body

Studies suggest mitragynine may exhibit anti-inflammatory properties by reducing pro-inflammatory cytokines.⁴ While promising, these findings are mostly preclinical. Clinical evidence supporting kratom as a reliable anti-inflammatory agent is limited, so users should approach these claims cautiously.

Some preliminary human data suggest that kratom may reduce subjective pain perception without the same gastrointestinal burden as NSAIDs, but robust clinical trials are lacking.

Organ-Specific Effects

• Gastrointestinal: Nausea, constipation, reduced appetite
• Cardiovascular: Elevated heart rate or mild blood pressure increase (rarely severe)
• Nervous system: Dizziness, headache, mild sedation
• Hepatic: Rare liver enzyme elevation (often from adulterated products)
• Other: Sweating, dry mouth, mild itching

Stimulant vs. Sedative Effects

Kratom’s dual action is unique, exerting contrasting effects at different doses. This trait makes the plant highly adaptable, allowing users to select the type of experience they’re after.

• Stimulant effects: Increased energy, alertness, and enhanced mood (often compared to caffeine but with mood modulation).
• Sedative effects: Relaxation, pain relief, and drowsiness; may reduce anxiety but can impair cognition at high doses.

Long-Term & Chronic Effects of Kratom

• Dependence and withdrawal: Irritability, insomnia, anxiety, and mood fluctuations; typically milder than classical opioids.
• Nutritional and weight changes: Appetite suppression and possible weight loss over time.
• Potential liver toxicity/injury: Rare, usually linked to contaminated or high-dose products.⁵

Due to limited clinical studies, the full spectrum of long-term health effects remains unclear, highlighting a significant research gap. For an evidence overview, see whether kratom is addictive.

Cognitive & Mental Health Impacts

Evidence on kratom's cognitive effects is mixed. Moderate use may enhance focus and mood stability, while high doses can impair attention and working memory. Psychological dependence is possible, particularly among those with prior substance use disorders.

How Long Does Kratom Stay in Your System?

• Onset: 30–60 minutes after ingestion
• Peak effects: 1–2 hours
• Duration: 4–6 hours (moderate doses); longer for higher doses
• Urine detection: Up to several days post-use, depending on dose

Factors such as age, liver function, hydration, and medication use influence metabolism and clearance rates.

How Long Does a Kratom High Last?

Subjective effects generally follow plasma concentration curves: low-dose stimulation lasts 2–3 hours, while sedative or analgesic effects persist 4–6 hours. Combining with other substances may extend or alter the experience.

Comparison: Kratom vs. Opioids & Other Substances

So, how does kratom compare to other substances when it comes to mechanisms of action, effects, and risks? Find out in the table below.

Note: Educational summary only. Does not constitute medical advice.

Practical Takeaways & Safety Considerations

• Start low: Gradually increase dose to gauge effects.
• Source quality: Use lab-tested, sustainably grown kratom.
• Avoid mixing: Combining with alcohol, opioids, or sedatives increases risk.
• Medical guidance: Those with cardiovascular, liver, or psychiatric conditions should consult a healthcare provider.

If you need preparation methods and formats, see how to take kratom.

Common Side Effects & Adverse Reactions

• Gastrointestinal: Nausea, constipation
• Cardiovascular: Elevated heart rate, mild blood pressure changes
• Nervous system: Dizziness, headache, sedation
• Other: Sweating, itching, dry mouth

Severe adverse events are rare and usually linked to adulterated products or extreme doses. For a deeper overview, see common kratom side effects and risks.

What You Need to Remember About Kratom’s Effects

• Effects are highly individual and strain-dependent.
• Clinical trials are limited; most evidence is observational or case-based.
• Product variability complicates dosing and predictability.
• Kratom addiction potential exists with heavy, prolonged use.

In short, kratom sits at the intersection of curiosity and caution. It may offer certain benefits, but it’s equally important to be mindful of its risks and uncertainties. If you choose to explore it, do so with moderation, reliable sourcing, and a genuine interest in understanding how your body responds.⁶

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References

1. Swogger MT, Smith KE, Garcia-Romeu A, et al. Understanding Kratom Use: A Guide for Healthcare Providers. Frontiers in Pharmacology. 2022;13. View on Frontiers in Pharmacology DOI: 10.3389/fphar.2022.801855 ⬆️ Back to text
2. Cinosi E, Martinotti G, Simonato P, et al. Following “the Roots” of Kratom (Mitragyna speciosa): ... BioMed Research International. 2015;2015:1-11. View on BioMed Research International DOI: 10.1155/2015/968786 ⬆️ Back to text
3. Wananukul W, Trakulsrichai S, Sathirakul K, et al. Pharmacokinetics of mitragynine in man. Drug Design, Development and Therapy. 2015. View on Drug Design, Development and Therapy DOI: 10.2147/DDDT.S79658 ⬆️ Back to text
4. Meireles V, Rosado T, Barroso M, et al. Mitragyna speciosa: Clinical, Toxicological Aspects and Analysis in Biological and Non-Biological Samples. Medicines. 2019;6(1):35. View on MDPI DOI: 10.3390/medicines6010035 ⬆️ Back to text
5. Kratom. PubMed. 2012. View on NCBI Bookshelf ⬆️ Back to text
6. WHO. Pre-Review Report: Kratom (Mitragyna Speciosa), Mitragynine, and 7-Hydroxymitragynine. 2021. View on WHO.int ⬆️ Back to text