Fadogia agrestis and tongkat ali: what science really says about this testosterone stack

Fadogia agrestis and tongkat ali are hyped as natural testosterone boosters, but the real story is more complicated than TikTok clips and Reddit threads. Here is what the research shows, what it doesn’t, and how to use these herbs safely if you choose to try them.

“Fadogia agrestis and tongkat ali sit at very different places on the evidence spectrum. Tongkat ali has several human trials and looks promising for men with low-normal testosterone. Fadogia, by contrast, is almost entirely based on animal data, so we have to treat the online excitement with a lot of caution.”

Alexander Grant, MD, PhD

The relationship

Over the last few years, fadogia agrestis and tongkat ali have become two of the most talked-about “testosterone hacks” in men’s health podcasts and forums. Both herbs come from traditional medicine systems and are marketed for libido, energy, and muscle support. But they are not equally studied, and they do very different things inside your body.

Tongkat ali, also known as Eurycoma longifolia, is a Southeast Asian root traditionally used as an aphrodisiac and anti-fatigue remedy. Several small human trials suggest it can increase testosterone in men with low or borderline levels and may improve sexual function and stress markers.^[1] Fadogia agrestis, a shrub from West Africa, has mainly been tested in rodents, where it raises testosterone-like hormones but also raises concern for potential toxicity at higher doses.

Both herbs are thought to act upstream at the level of luteinizing hormone (LH). LH is a pituitary hormone that tells the testicles to make testosterone. In theory, gently nudging LH higher may help men whose lab work shows “low-normal” testosterone but who do not yet qualify or wish for prescription testosterone therapy. Meta-analyses indicate that men with symptoms and total testosterone below about 350 ng/dL (≈12 nmol/L) or free testosterone below 100 pg/mL (≈10 ng/dL) are most likely to benefit from medical testosterone therapy, not just supplements.^[2]

How it works

To understand fadogia agrestis and tongkat ali, you need a quick tour of the male hormone axis and how each herb appears to act along it.

Hormone signaling and luteinizing hormone

The hypothalamic–pituitary–gonadal (HPG) axis is the hormonal chain that runs from the brain to the testicles. The hypothalamus releases GnRH, which tells the pituitary gland to release luteinizing hormone (LH). LH then stimulates Leydig cells in the testicles to produce testosterone.

Animal data suggest that both fadogia agrestis and tongkat ali may increase LH secretion or LH-like signaling, which in turn can raise testicular testosterone production.^[1] Human trials of tongkat ali show modest but significant increases in total and free testosterone in men with low baseline levels, consistent with a mild LH-driven effect.^[1]

Sex hormone binding globulin and free testosterone

Sex hormone binding globulin (SHBG) is a protein that grabs onto testosterone in the blood. “Free” testosterone is the small fraction not bound to SHBG and is available for tissues like muscle and brain to use. Higher SHBG usually means less free testosterone.

In one randomized study, tongkat ali supplementation was associated with reduced SHBG and a resulting increase in calculated free testosterone in stressed men, along with improvements in mood and libido. Lowering SHBG can be particularly useful in older men or men with thyroid or liver issues, where SHBG tends to run high even when total testosterone looks “normal.”

Stress hormones and the “fight or flight” response

Cortisol is a stress hormone made by the adrenal glands. Chronically high cortisol can suppress testosterone production and worsen sleep, mood, and body composition. Some tongkat ali extracts have been shown to reduce salivary cortisol and improve tension and anger scores in moderately stressed adults.

By nudging cortisol down and testosterone up, tongkat ali may shift the balance of stress and sex hormones in a more favorable direction for energy, libido, and training recovery. This does not treat severe anxiety or depression but may support overall resilience when paired with good sleep and exercise.

Testicular function and potential toxicity

Testicular histology is the microscopic structure of testicular tissue, including the cells that make sperm and testosterone. Rodent studies of fadogia agrestis show increased testosterone and mounting behavior at moderate doses but also signs of testicular damage and altered liver enzymes at higher doses and longer durations.

No controlled human trials of fadogia agrestis currently exist, and there are no standardized dosing or safety guidelines. This means that any use of fadogia in humans is based on extrapolating from animal data, which may not translate cleanly and may underestimate risk.

Diagnostic thresholds and when herbs are not enough

Clinical hypogonadism is low testosterone with symptoms plus documented low levels on blood tests. Most major guidelines suggest that symptomatic men with total testosterone below 350 ng/dL, or free testosterone below 100 pg/mL, are the ones most likely to benefit from prescription testosterone therapy after reversible causes are addressed.^[2]

In this group, fadogia agrestis and tongkat ali are unlikely to fully correct hormone levels or symptoms on their own. They may play a minor supportive role, but they do not replace medically supervised testosterone therapy when it is clearly indicated.

Conditions linked to it

Men usually look at fadogia agrestis and tongkat ali because of problems that may be linked to low or borderline testosterone. The key conditions include:

Functional low testosterone (“low-normal” T): Men with fatigue, low libido, and poor recovery, whose testosterone sits in the lower end of the reference range. Tongkat ali shows the most promise here, with small human trials demonstrating modest increases in testosterone and reported improvements in sexual function and vitality.^[1]
Age-related testosterone decline: Testosterone levels gradually fall with age, roughly 1% per year after the 30s in many men.[4] Tongkat ali may offer a mild boost for men who are symptomatic but not yet candidates, or not interested in, full testosterone replacement.
Stress-related sexual dysfunction: Chronic stress, poor sleep, and high cortisol can blunt libido and erections. Tongkat ali’s effects on stress markers and mood may indirectly support sexual performance.
Infertility concerns: Animal and early human data suggest tongkat ali might improve sperm concentration and motility, although studies are small and often industry sponsored.^[3] For fadogia agrestis, rodent studies raise concern about potential testicular toxicity, which could in theory harm fertility rather than help it at higher doses.
Metabolic health and body composition: Low testosterone is linked with increased fat mass, lower muscle mass, and insulin resistance. Mild improvements in testosterone and stress response from tongkat ali could support better training and body composition, but they are not a replacement for diet and exercise.^[2]

Limitations note: For fadogia agrestis, nearly all data are from animal or in vitro studies. For tongkat ali, most human trials are small, short-term, and often use proprietary extracts. There are no large, long-term safety trials for either herb.

Symptoms and signals

If you are curious about fadogia agrestis and tongkat ali, you are probably noticing some of these common signs that push men toward “T-boosting” protocols:

Lower sex drive or less frequent sexual thoughts than usual
Weaker morning erections or fewer spontaneous erections
Difficulty achieving or maintaining an erection firm enough for sex
Fatigue that does not match your workload or sleep schedule
Slower recovery from workouts, more soreness, or loss of strength
Increase in belly fat or trouble building or maintaining muscle
Mood changes, such as more irritability, low motivation, or “flat” mood
Brain fog, poor concentration, or feeling mentally slower
Poor sleep quality, especially if paired with snoring or suspected sleep apnea
Fertility concerns, such as difficulty conceiving with a partner

None of these symptoms prove you have low testosterone. They can also come from sleep disorders, depression, thyroid problems, medications, heavy alcohol or cannabis use, or overtraining. That is why lab testing and a full evaluation are essential before you assume hormones are the only issue.

What to do about it

If you are considering fadogia agrestis and tongkat ali, a structured plan will help you avoid wasted money and unnecessary risk.

Step 1: Get tested and rule out bigger problems
Ask your clinician for morning fasting blood work that includes total testosterone, free testosterone, SHBG, LH, prolactin, and basic labs like CBC, CMP, and lipid profile. For most men, I also recommend screening for thyroid function and checking for sleep apnea if snoring or daytime sleepiness are issues. If your total testosterone is below 350 ng/dL or free testosterone is below 100 pg/mL on two separate mornings, you should discuss guideline-based treatment options, not just supplements.^[2]
Step 2: Fix the foundations, then consider tongkat ali first
Before you reach for fadogia agrestis and tongkat ali, tighten up the big levers:
- Sleep 7–9 hours with consistent bed and wake times
- Lift weights 2–4 times per week and walk daily
- Limit alcohol, avoid nicotine, and moderate cannabis
- Maintain a healthy body fat level and adequate protein intake
If symptoms persist and your levels are low-normal, a trial of tongkat ali is reasonable for many men. Human studies commonly use 200–400 mg per day of standardized extract, often split into one or two doses, for 4–12 weeks.^[1] Start at the low end, avoid stacking multiple new supplements at once, and skip fadogia unless you fully understand the lack of human safety data and are working with a clinician.
Step 3: Monitor, adjust, and know when to stop
Re-check symptoms, blood pressure, and labs after 8–12 weeks. Watch for side effects such as insomnia, irritability, acne, or changes in blood counts or liver enzymes. If you do not feel better and lab numbers have not moved meaningfully, stop the supplement. If you do feel better but your baseline testosterone was frankly low, talk with your clinician about whether formal testosterone therapy or a fertility-preserving option, such as clomiphene citrate, makes more sense for the long term.^[2]

Myth vs Fact: Fadogia agrestis and tongkat ali

Myth: “Fadogia agrestis has been proven in humans to triple testosterone.”
Fact: There are no published human trials of fadogia agrestis as of 2024. All testosterone data come from rodent studies, some of which also show potential testicular toxicity at higher doses.
Myth: “Tongkat ali works just like prescription testosterone replacement therapy (TRT).”
Fact: Tongkat ali appears to mildly increase your own testosterone production and adjust SHBG and stress hormones. Prescription TRT replaces testosterone directly and generally produces larger, more predictable changes in blood levels.^[1],[2] You can learn more about how TRT works, and how it differs from herbs, in this overview of testosterone replacement therapy side effects and management.
Myth: “Natural herbs are automatically safer than pharmaceutical options.”
Fact: Herbal supplements are not FDA-regulated like drugs. Products can be under-dosed, over-dosed, contaminated, or adulterated. Fadogia agrestis in particular lacks basic human safety data, and rodent work raises red flags for testes and liver at high doses.
Myth: “If my testosterone is 250 ng/dL, I should just try herbs before seeing a doctor.”
Fact: A total testosterone of 250 ng/dL is below typical treatment thresholds. Guidelines recommend full evaluation and discussion of medical therapy, because low testosterone can be a sign of pituitary disease, testicular failure, or other serious problems that herbs will not fix.^[2]
Myth: “More is better—stacking higher doses of fadogia agrestis and tongkat ali will speed results.”
Fact: Higher doses may increase side effects without proven extra benefits. For fadogia, higher doses are exactly where animal studies start to show organ toxicity. For tongkat ali, published studies stay within the 200–400 mg per day range.^[1]

Bottom line

Fadogia agrestis and tongkat ali are not magic testosterone switches. Tongkat ali has several human studies showing modest increases in testosterone and improvements in stress and sexual function for men with low-normal levels, and it is a reasonable option to trial under medical guidance. Fadogia agrestis, in contrast, is still almost entirely an animal story, with signals of possible testicular and liver toxicity at higher doses. If you are dealing with symptoms of low testosterone, start with lab work, lifestyle, and a conversation with a clinician. Then, if you decide to experiment, do it in a way that is measured, monitored, and honest about what the science can—and cannot—promise today.

References

George A, Henkel R. Phytoandrogenic properties of Eurycoma longifolia as natural alternative to testosterone replacement therapy. Andrologia. 2014;46:708-21. PMID: 24386995
Bhasin S, Brito JP, Cunningham GR, et al. Testosterone Therapy in Men With Hypogonadism: An Endocrine Society Clinical Practice Guideline. The Journal of clinical endocrinology and metabolism. 2018;103:1715-1744. PMID: 29562364
Tambi MI, Imran MK. Eurycoma longifolia Jack in managing idiopathic male infertility. Asian journal of andrology. 2010;12:376-80. PMID: 20348942
Corona G, Tirabassi G, Santi D, et al. Sexual dysfunction in subjects treated with inhibitors of 5α-reductase for benign prostatic hyperplasia: a comprehensive review and meta-analysis. Andrology. 2017;5:671-678. PMID: 28453908
Kelly DM, Jones TH. Testosterone: a metabolic hormone in health and disease. The Journal of endocrinology. 2013;217:R25-45. PMID: 23378050
Isidori AM, Giannetta E, Greco EA, et al. Effects of testosterone on body composition, bone metabolism and serum lipid profile in middle-aged men: a meta-analysis. Clinical endocrinology. 2005;63:280-93. PMID: 16117815