The side effects most commonly reported with kratom are constipation, nausea, dry mouth, dizziness, drowsiness, and loss of appetite. Mayo Clinic and WebMD list the same core group, and it matches what users describe in community forums. Most of these are reported as dose-dependent: people tend to describe them as mild or absent at lower amounts and more frequent at higher ones. Regular heavy use carries a different and more serious risk, which is dependence.
Below we go through what each reported effect looks like, why the amount matters more than the strain, which serious risks have been documented, and the one factor you can control completely: whether the product is clean.
Safety & legal note. Kratom is not approved by the FDA for any use, and nothing here is medical advice. This article reports what public health sources and users commonly describe; it is not a complete list, and individual response varies. If you take prescription medication or have a medical condition, talk to a clinician before using kratom. Kratom is banned in some US states and is not for anyone under 21. Check your local law.
The commonly reported side effects
These are the effects that come up again and again in both clinical summaries and user reports:
| Reported effect | How users commonly describe it |
|---|---|
| Constipation | The most-named complaint among regular users |
| Nausea / upset stomach | Usually tied to taking too much, or taking it on an empty stomach |
| Dry mouth | Common and mild; people mention drinking more water |
| Dizziness / "wobbles" | A spinning or unsteady feeling, mostly reported at higher amounts |
| Drowsiness / tiredness | More often linked to red veins and larger amounts |
| Reduced appetite | Reported fairly often; weight loss shows up with long-term use |
| Sweating / itching | Less common, but mentioned regularly |
Two patterns stand out. First, almost every item on that list gets worse with the amount taken. Second, most of the list looks like the familiar profile of compounds that act at opioid receptors. That is not a coincidence. Kratom's main alkaloid, mitragynine, and its metabolite 7-hydroxymitragynine both bind there, as we explain in is kratom an opioid?.
Does kratom cause constipation?
Yes, it is the most consistently reported effect. It has the same cause as opioid-related constipation: receptor activity in the gut slows motility. Users who take kratom regularly describe it as the side effect most likely to persist, while effects like nausea tend to fade once they settle on a consistent routine.
Users report what you would expect helps: drinking more water, eating more fiber, and not escalating the amount. If constipation becomes severe or does not resolve, see a doctor.
Does kratom make you tired?
It depends on the amount and the vein, and this is where kratom's reputation gets confusing. Users commonly describe kratom as stimulating at lower amounts and sedating at higher ones. That two-sided profile is why the same plant shows up in both "best kratom for energy" and "best kratom for sleep" searches.
So people who report feeling tired have often taken more than they intended, or chosen a red vein, which community sources consistently associate with relaxation rather than energy. Some also describe a dip in energy as the effect wears off.
Nausea and the "wobbles"
Nausea is the effect most closely tied to taking too much at once, and also to taking powder on an empty stomach. The "wobbles" are a user term for a dizzy, visually unsteady feeling, and they get the same explanation. Both are reported far more at higher amounts, and both are the main reason "start low" is the most common advice in kratom communities.
Potency adds a catch. Alkaloid content varies from batch to batch, so the same weighed amount from a stronger batch is effectively a bigger dose. Our dosage guide explains why a gram is a unit of weight, not of strength.
Serious risks that have been documented
Beyond everyday side effects, public health sources document risks that are less common but more serious:
- Dependence and withdrawal. Regular heavy use can lead to dependence. Reported withdrawal symptoms resemble mild opioid withdrawal: irritability, muscle aches, runny nose, trouble sleeping, and cravings. This is the risk most consistently confirmed by research.
- Liver injury. Case reports describe liver injury in some users, though rarely.
- Seizures and high blood pressure. Both appear in case reports, mostly at high amounts or with other substances involved.
- Interactions. Combining kratom with alcohol, opioids, benzodiazepines, or other sedating drugs is where the most serious outcomes concentrate. Kratom also affects liver enzymes that process many prescription medications.
The concentrated products deserve a separate mention. In July 2025 the FDA announced it would recommend scheduling concentrated 7-hydroxymitragynine (7-OH) products. Those are semi-synthetic, far more potent, and a separate category from whole-leaf kratom. We compare them in kratom vs 7-OH. Many of the worst side-effect stories online involve 7-OH or extracts, not plain leaf powder.
Side effects you can actually prevent: contamination
Some reported harms have nothing to do with kratom's alkaloids. They come from what else is in the bag. In 2018 the FDA linked a multistate salmonella outbreak to kratom products. In 2019 its testing of 30 products found lead and nickel at levels of concern for long-term daily use.
Those are manufacturing failures, and they are the part of the side-effect picture a buyer controls completely. Look for:
- Per-batch third-party testing, with a current certificate of analysis covering heavy metals and microbials.
- AKA GMP qualification, the industry's independently audited manufacturing standard.
- Published alkaloid content, so you know whether a batch is stronger than the last.
We cover the testing side in detail in is kratom safe?.
Where to buy
Buying tested product is the simplest way to avoid contamination-related harm, and it makes potency predictable.
Our code getketum takes 15% off at Kraken Kratom, our #1-ranked vendor. Kraken is AKA GMP qualified, tests every batch, and publishes its average mitragynine content, which helps if you want consistent strength from one order to the next. It's the only coupon we carry, so it's the one to use.
Also worth comparing: Kats Botanicals, with batch-level COA lookup and a broad capsule menu, and Kona Kratom, a third-party tested value brand with a money-back guarantee. See the full ranked comparison at best kratom vendors.
The bottom line
- The most commonly reported kratom side effects are constipation, nausea, dry mouth, dizziness, drowsiness, and reduced appetite.
- The amount drives most of them. Users describe kratom as stimulating at lower amounts and sedating at higher ones, and side effects rise with the amount.
- Constipation is the most persistent complaint; nausea and the wobbles are most tied to taking too much at once.
- Dependence is the serious long-term risk, and mixing kratom with alcohol or other sedating drugs is where the worst outcomes concentrate.
- Concentrated 7-OH products are a different category from whole leaf and account for many of the worst reports.
- Contamination is preventable. Buy per-batch tested, ideally AKA GMP-qualified product, and talk to a clinician if you take any medication.