What are the study effects and any safety issues with supplementing with tongkat ali

Tongkat ali has some human-study evidence for hormone and libido effects, but the evidence is limited and responses may vary.

• Hormone effects: It may increase total and free testosterone, and can slightly raise DHEA. It may lower sex hormone–binding globulin (SHBG) mainly in people whose SHBG is high; studies in people with normal SHBG did not show that effect. The proposed mechanisms include effects on testosterone-synthesis pathways and weak effects on aromatase and estrogen receptors. 1 2
• Libido: Some studies and reports suggest improved libido or sexual function, but the discussion notes there are fewer robust controlled studies for tongkat ali than for maca. 3
• Safety and practical cautions: It may feel mildly stimulating and can interfere with sleep if taken late; Andrew Huberman described feeling overstimulated at doses above 400 mg. Because it can affect hormone pathways, the speakers recommend medical guidance and monitoring bloodwork, including hormone levels and liver enzymes. Advice on cycling differs: one discussion says cycling is likely unnecessary, while another suggests 11 months on and one month off as a cautious approach. 4 5 6
• Dose and product: Discussed doses range from 200–600 mg/day in one episode and 300–1,200 mg/day in another; the speakers emphasize starting low and paying attention to extract standardization. These are not a single agreed-upon dose recommendation. 7 8

The transcripts describe possible benefits, not a guarantee of effect or comprehensive proof of long-term safety.