Fadogia agrestis is a shrub of the West African savanna whose stem is used in Nigerian traditional medicine as an aphrodisiac and for fever. It became a supplement after a 2005 study in rats reported more mounting, longer ejaculatory latency and higher testosterone, and it has since been promoted on podcasts as a natural testosterone booster, often stacked with tongkat ali.

Everything known about it in a living body comes from one Nigerian laboratory's rat work, and that work is not all good news. The same group that reported the aphrodisiac effect went on to report testicular changes at every dose tested and signs of cell-membrane damage in liver and kidney. No human study exists: not a trial, not a case series, not a pharmacokinetic study.

Phytochemical screening found alkaloids and saponins, with anthraquinones and flavonoids weakly present. The proposed mechanism is a rise in testosterone, inferred from the rat serum levels. A 2023 rat study reported the extract restored nitric oxide and cGMP signaling and antioxidant enzymes in penile and testicular tissue of rats given paroxetine to blunt sexual function. No constituent has been shown to do anything in a human.

The study it is sold on. Male rats dosed orally at 18, 50 or 100 mg per kg for five days showed increased mount and intromission frequency, longer ejaculatory latency, shorter mount and intromission latency, and a dose-related rise in serum testosterone.

The follow-up the sellers do not quote. The same group gave rats the same doses daily for 28 days. At every dose, testis-to-body weight ratio rose and testicular cholesterol, sialic acid, glycogen and several enzymes shifted, while testicular protein fell. The authors describe these as indications of adverse effects on testicular function, with recovery seen mainly at the lowest dose after a 10-day washout.

Liver and kidney. In the same 28-day design, enzymes leaked from liver and kidney into serum and serum malondialdehyde rose at every dose, which the authors read as peroxidation of cell membranes in hepatocytes and nephrons. No deaths, no organ swelling, no clinical signs.

Rat erectile model. In 2023 the extract at the same three doses restored nitric oxide pathway markers in paroxetine-treated rats, comparably to sildenafil, and the authors recommended clinical trials. None has been run.

What is in the bottle. A 2019 analytical study developed a method to quantify eleven phenolic compounds and tested 17 dietary supplements claiming to contain fadogia: twelve contained the compounds at 0.3 to 2.7 mg per day, and five contained none detectable.

No human safety data of any kind. The animal file shows testicular changes at every dose after 28 days, cell-membrane damage in liver and kidney at every dose, and recovery only at the lowest dose, 18 mg per kg, which the authors note is the folk-medicine dose. The supplement doses sold online are not derived from that figure by any published method.

The two findings together, a testosterone rise and testicular toxicity, are consistent with a testicular irritant rather than a tonic. That is a hypothesis, because nothing has been measured in people. The honest position is that nobody knows what a daily human dose does, and the only organ-level data that exist point the wrong way.

Sold as a dietary supplement in the United States without any review, which is legal because the law does not require evidence for a botanical ingredient on the market. Not an authorized novel food in the European Union, so it has no lawful food status there. Not a licensed medicine anywhere. Five of 17 products tested in 2019 contained none of the plant's marker compounds.