Tongkat Ali and Fadogia Agrestis: What the Studies Show, and the Fadogia Problem Nobody Mentions

Two herbs went from obscurity to the top of every testosterone search in about eighteen months, largely because one podcast host said he takes them. Tongkat ali and fadogia agrestis are now in most "test booster" formulas sold in India, including ours.

They are not the same case. One has human trials, a known active compound and a reasonable safety record. The other has rat studies, no human safety data, and one finding that should make anyone using it pay attention to their bloodwork.

Tongkat ali: what it is

Eurycoma longifolia is a Malaysian root with a long history in traditional use. The active compounds are quassinoids, the main one being eurycomanone. The proposed mechanisms include release of testosterone from its carrier protein SHBG, a mild reduction in cortisol, and some stimulation of the signalling that drives testosterone production.

Standardisation matters. A useful extract is concentrated at least 100:1 and standardised to a stated eurycomanone content, typically 1 to 2 percent. Raw root powder at 200 mg does nothing, and most cheap products are raw powder.

The human trials on tongkat

• Tambi et al., 2012 — 76 men with late-onset hypogonadism, 200 mg per day for 1 month. Testosterone rose, and over 90 percent moved into the normal range.
• Talbott et al., 2013 — 63 moderately stressed adults, 200 mg per day for 4 weeks. Cortisol fell 16 percent and salivary testosterone rose 37 percent.
• Henkel et al., 2014 — 25 older adults aged 57 to 72, 400 mg per day for 5 weeks. Total and free testosterone rose, and muscle force improved.
• Leitao et al., 2021 — older adults in a training programme, 200 mg per day for 6 months. Testosterone and strength improved more than training alone.
• Chan et al., 2021 — healthy young men with low-normal testosterone, 600 mg per day for 2 weeks. A small rise in testosterone.

A 2022 systematic review by Leisegang and colleagues pooled the randomised trials and found a consistent increase in total testosterone, with the largest effects in men who started low. Most of the trials are small, several were funded by extract manufacturers, and the follow-up is short.

What tongkat does not do

In healthy men with normal testosterone, the effect is small, in the region of a few percent, and sometimes absent. The rise seen in the trials came from men starting in the low or low-normal range, and it brought them toward normal rather than above it.

That is the honest framing. Tongkat can move a man from 350 ng/dL toward 450. It will not take a man at 600 to 900, and it is not an alternative to a cycle for anyone who wants that. The serum testosterone PK model shows what exogenous testosterone actually does to blood levels over time, which puts a herb's effect in proportion.

Fadogia agrestis: what exists

Fadogia agrestis is a Nigerian shrub. The evidence is a handful of rat studies from a single research group at the University of Ilorin.

In 2005, Yakubu and colleagues gave male rats an aqueous stem extract at 18, 50 and 100 mg/kg for five days. Testosterone rose at all doses, and sexual behaviour increased. This is the study every fadogia product is sold on.

In 2008, the same group ran the extract for 28 days at the same doses. Testicular weight rose, and the markers they measured of testicular cell integrity changed in a pattern the authors described as suggestive of toxicity to the testes. That study is not on any product label.

There are no published human trials of fadogia agrestis. None on testosterone, none on safety, none on dose.

The fadogia problem, stated plainly

A compound that raises testosterone in rats for five days and damages testicular tissue markers in rats over 28 days, with zero human data, is being taken daily by a large number of men on the basis of a podcast.

The three-weeks-on, one-week-off cycling advice that circulates is a guess, not a protocol derived from anything. The rat doses do not translate cleanly to a human dose, and an aqueous stem extract is not the same as the ethanolic 10:1 extracts sold as supplements. So the risk could be smaller than the rat study suggests, or it could be larger. Nobody knows, and that is the point.

If you use it, use it with bloodwork. Total testosterone, LH and FSH before and after eight weeks tell you whether it is doing anything. Liver enzymes and creatinine tell you whether it is doing harm. Rising LH with falling testosterone is the pattern that would suggest the testes are struggling, and it is the one to stop for.

How to use either with bloodwork

1. Test first: total testosterone, SHBG, LH, FSH, oestradiol, and a liver panel. Morning, fasted.
2. Run the herb for eight weeks at the studied dose. For tongkat, 200 to 400 mg of a standardised extract.
3. Retest the same panel at the same time of day.
4. Compare. A change smaller than the normal daily variation of testosterone, which is around 15 to 20 percent, is not a result.

The bloodwork analyzer reads testosterone with SHBG and LH, which shows whether a rise came from more production or from less binding, and the blood test selector builds the before-and-after panel so you are not paying for tests you do not need.

Our position

GOD OF TEST from God of Supps, our own formula, contains tongkat ali at 500 mg of a 200:1 extract and fadogia agrestis at 300 mg of a 10:1 extract, alongside KSM-66 ashwagandha, shilajit, DIM, turkesterone and vitamin D3 with K2. The same rules apply to it as to anything else in this article.

It is for men in the low-normal range who want a measurable nudge, not a replacement for a medical evaluation of low testosterone. The tongkat is the ingredient with human trials behind it; the fadogia carries the uncertainty described above. Run it with bloodwork, take breaks, and stop if the numbers move the wrong way. A brand that tells you otherwise is describing the herb it wishes it were selling.

The short version

Tongkat ali has small human trials showing modest testosterone increases, mostly in men who start low. Fadogia agrestis has rat studies, no human data, and a 28-day rat study that flagged testicular toxicity markers. Neither replaces a medical workup. Use them with before-and-after bloodwork, watch LH and liver enzymes, and expect a nudge rather than a transformation.

Related tools

• Bloodwork analyzer: reads testosterone with SHBG and LH to show where a change came from
• Blood test selector: builds the before-and-after panel for a supplement trial
• Serum testosterone PK model: puts a herb's effect in proportion to what exogenous testosterone does

Frequently asked questions

Does tongkat ali increase testosterone?

In small trials, yes, mostly in men with low or low-normal levels. The effect is modest, and in healthy men with normal testosterone it is small or absent.

What dose of tongkat ali was used in studies?

200 to 400 mg per day of a standardised extract, usually 100:1 or 200:1, in trials running four weeks to six months. Raw root powder at those doses is not comparable.

Is fadogia agrestis safe?

Unknown. There are no human safety studies. A 28-day rat study found changes in testicular markers that the authors considered suggestive of toxicity. Anyone using it should monitor testosterone, LH and liver enzymes.

Does fadogia agrestis raise testosterone in humans?

No human trial has tested it. The claim rests on a five-day rat study from 2005. Any effect in humans is inferred, not demonstrated.

Should you cycle tongkat ali and fadogia?

The cycling advice in circulation is not based on trial data. Taking breaks is reasonable given the unknowns, particularly with fadogia, but the specific schedule is a guess.

Can these herbs replace TRT?

No. The increases seen with tongkat are in the range of tens of ng/dL, and fadogia has no human data. Men with confirmed low testosterone and symptoms need a medical evaluation, not a herb.

This article is educational and is not medical advice. See the medical disclaimer.