Kratom: effects, risks and dependence

Kratom is an unusual botanical because its effects change with the amount taken. Users in Southeast Asia traditionally chewed the leaves, or made tea, to fight fatigue and improve work productivity. At higher amounts the same leaves have been used to relieve pain and diarrhoea, sometimes as an opium substitute. People who use it report both stimulant-like effects such as energy, alertness and a rapid heartbeat, and opioid- and sedative-like effects such as relaxation, pain relief and confusion.

Two alkaloids, mitragynine and 7-hydroxymitragynine, bind to opioid receptors in the brain, which explains why kratom is often discussed alongside opioid dependence even though it is a plant sold as powder, capsules, extracts or drinks.

NIH states that very little research in people has evaluated kratom, that research is in its early stages, and that it has not been shown to be safe and effective for any medical use. Some people in Western countries take it to try to manage pain or opioid withdrawal symptoms and cravings, and researchers are examining that question.

A systematic review of kratom and mental health published in 2018 found that kratom may serve some people as a harm-reduction substitute for opioids and that many users report improved mood and less anxiety. It also found that withdrawal symptoms were mild for many, relative to opioids, but highly uncomfortable for some, making abstinence hard. Self-reported benefit is not the same as demonstrated safety, and these findings come largely from surveys of users rather than controlled trials.

Reported side effects span mild effects (nausea, constipation, dizziness, drowsiness) and rare but serious ones, including seizures, high blood pressure and liver problems. NIH reports that long-term use of large amounts has been associated with serious liver problems in some people, and that the long-term effects of kratom are poorly understood.

Fatal overdoses from kratom alone appear to be extremely rare according to NIH, but the use of kratom together with other drugs has been linked to deaths and severe adverse effects. Combining it with alcohol, opioids, benzodiazepines, gabapentinoids or other sedatives is therefore especially risky, because sedation and breathing depression can add together.

• Seek urgent help (999) for fits, collapse, severe drowsiness, slow or shallow breathing, chest pain or confusion after kratom.

• See a GP promptly for yellow skin or eyes, dark urine, persistent nausea or upper abdominal pain.

• Do not drive or use machinery if you feel drowsy, dizzy or confused.

Although people use kratom to try to overcome opioid addiction, NIH notes that kratom itself may have the potential to be addictive and that regular users can have withdrawal symptoms if they stop. Someone who is daily dependent, or who has been using it alongside opioids, should speak to a GP or local drug and alcohol service rather than stopping abruptly alone. NHS and local services can offer confidential support, and a pharmacist can advise on interactions with prescribed medicines.

A review of kratom pharmacology and clinical implications from 2020 describes increasing use in several parts of the world and a pharmacology similar in some respects to opioids, with concern for dependence and addiction. That is a reason for patients to mention kratom openly to any clinician assessing unexplained sedation, abnormal liver tests or withdrawal-like symptoms.

Kratom products are not manufactured to the standards that medicines must meet. NIH reports that harmful contaminants such as heavy metals and disease-causing bacteria have been found in some products, so two packets with the same name may differ in strength and purity. Concentrated extracts and "shots" can contain far more of the active alkaloids than leaf powder, which raises the risk of overdose.

Kratom is not a licensed medicine and there is no regulatory finding in the sources used here that it is safe for any therapeutic purpose. Its legal and regulatory status can change, so check current UK government information and do not assume that availability means safety.

No source retrieved for this guide establishes safe use in pregnancy, breastfeeding or childhood. Because it acts on opioid receptors, a newborn exposed to a regularly using mother may be at risk of withdrawal, so anyone who is pregnant and using kratom should tell their midwife or GP early. Tell any clinician who prescribes you analgesics, antidepressants, anti-epileptics or sedatives that you use it, since NIH says interactions have been linked to deaths and more research is needed on them.