Short answer: Tongkat ali has small human trials; Fadogia agrestis has none. A meta-analysis of 5 tongkat ali trials found higher testosterone in men.1 Fadogia raised testosterone in rats over 5 days, but 28 days harmed testicular measures and liver and kidney cells in rats.234 Its effects and safety in people are unknown.
| Tongkat ali | Fadogia agrestis | |
|---|---|---|
| Studied in people? | Yes, small randomized trials1 | No human studies found |
| Testosterone | Higher total testosterone in a meta-analysis of 5 trials1 | Raised in male rats over 5 days2 |
| Longer-term findings | 4 weeks in 63 stressed adults: lower cortisol5 | 28 days in rats: adverse changes in testicular function, partial recovery only at the lowest dose3 |
| Liver and kidney | Not flagged in the trials cited | Signs of cell damage in rat liver and kidney at 28 days4 |
| Label testing | Not covered in the sources checked | 5 of 17 supplements had none of the plant's marker compounds6 |
| FDA approval | Supplements are not approved before sale7 | Same7 |
Tongkat ali has been tested in people. A 2022 meta-analysis of 5 randomized trials found higher total testosterone, including in men with low testosterone, while the authors called for more research before clinical use.1
Fadogia agrestis has only been tested in male rats given 18, 50 or 100 mg of stem extract per kg of body weight. Over 5 days, testosterone and mating behavior rose.2 Over 28 days at the same doses, the same group reported changes in testicular measures they called adverse, with recovery mainly at the lowest dose,3 and signs of damage to liver and kidney cell membranes.4 Rat results often do not carry over to people, in either direction.
These are study protocols, not personalized advice; confirm any dosing with your prescriber.
University of Mississippi researchers tested 17 supplements claiming to contain Fadogia agrestis; 5 had none of the plant's marker compounds.6
If you are on TRT, ask your prescriber before adding either. More detail: Maca vs tongkat ali: which affects testosterone?, Ashwagandha vs tongkat ali: how do the two herbs compare?, and the Tongkat Ali and Fadogia Agrestis guides.