Comparative guide · 11 min read

Tongkat ali vs fadogia vs forskolin vs ashwagandha — testosterone evidence ranked

Updated 2026-05-27 · Reviewed by SupplementScore editors · No sponsorships

These four are the "T-stack" of the podcast era. They are not equivalent in evidence: one has multiple placebo-controlled human RCTs, one has a thin layer of small human studies, one has decent human data for body composition with weaker testosterone-specific evidence, and one is almost entirely rodent science being sold to humans. We rank them by the human evidence that exists — not by the marketing.

Quick verdict

GoalBetter-supported optionWhy
Total testosterone change in men with low-normal baseline Tongkat ali Multiple human RCTs at 200–400 mg/day standardised extract show small-to-moderate increases in total/free testosterone and reductions in cortisol/SHBG-bound fraction.
Stress-related libido and stress-induced T suppression Ashwagandha Stronger evidence for cortisol reduction and vitality scores than for raw testosterone. Useful when the limiting factor is chronic stress.
Sub-fertility / oligospermia with normal-low T Ashwagandha The 2013 Ambiye pilot in oligospermic males showed sperm-parameter improvements at 675 mg/day root extract for 90 days.
Body composition in overweight men (with caloric work) Forskolin Godard 2005 showed body-fat reduction and a modest free-testosterone rise at 250 mg/day of a 10% forskolin extract. Small trial; replicate cautiously.
"Fadogia raises my testosterone" (the popular claim) Skip — there is no published human RCT All efficacy data is rodent; chronic dosing safety data in humans is essentially absent.
Lowest cost per evidence-graded daily dose Ashwagandha Standardised 600 mg/day extracts run ~$0.20–0.50/day. Tongkat ali at trial-validated dose runs $0.50–1.50/day.

Per-option deep dive

Tongkat ali (Eurycoma longifolia) — the strongest specifically-for-T evidence

Tongkat ali is the rhizome of a Southeast Asian shrub; the active fraction includes quassinoids (eurycomanone is the lead candidate) and glycoproteins thought to modulate sex-hormone-binding globulin (SHBG) and reduce stress-induced testosterone suppression. The standardised water-extract preparation called Physta is what most positive trials used.

The 2012 Tambi trial of 76 hypogonadal men given 200 mg/day Physta for one month reported modest total-testosterone increase and symptom improvement on the AMS (Aging Male Symptom) scale. The 2012 Ismail trial randomised 109 men aged 30–55 to 300 mg/day Physta vs placebo for 12 weeks, finding improved quality of life and erectile function scores. Henkel 2014 in physically active seniors (n=25) at 400 mg/day for 5 weeks showed strength and free-testosterone increases. The 2021 Leitão trial (a 6-month, double-blind, placebo-controlled study with concurrent training in androgen-deficient aging men) found tongkat ali improved erectile function and modestly raised testosterone with concurrent training relative to training alone.

Dose: 200–400 mg/day standardised extract (Physta-class), taken in the morning. Effects tend to develop over 4–12 weeks.

Tolerability: Well-tolerated in trials. Insomnia at higher doses or evening dosing. Some reports of irritability or anxiety in sensitive users at >400 mg/day.

Safety: Avoid in prostate cancer or active hormone-sensitive cancer (theoretical concern). Avoid in pregnancy and breastfeeding. Heavy-metal contamination has been a real concern with low-cost raw-leaf or root powders; choose third-party-tested standardised extracts.

Fadogia agrestis — the rodent-only molecule being sold to humans

This is the awkward one. The popular "fadogia raises T" claim traces almost entirely to a 2005 Yakubu rat study, which reported dose-dependent serum testosterone increases in male albino rats after aqueous fadogia stem extract for five days. The mechanism appears to involve increased LH stimulation of testicular Leydig cells. That is the entire seminal study. The follow-up literature is overwhelmingly rodent-based and short-duration.

There is currently no published, peer-reviewed, placebo-controlled human RCT demonstrating testosterone elevation from fadogia in men. There is also limited chronic-dosing toxicology in humans. Animal models have raised concerns about testicular and hepatic toxicity at higher rodent doses, though dose-translation to humans is uncertain. The supplement market has run far ahead of the evidence.

Dose claimed in marketing: 600 mg/day. This is extrapolated from rodent data using a body-surface-area conversion, not derived from a human trial.

Position: If you are taking fadogia, you are participating in an uncontrolled experiment on yourself. That is a defensible thing to do for some people; it is not a defensible thing for us to recommend.

Forskolin (Coleus forskohlii) — body comp first, testosterone second

Forskolin activates adenylyl cyclase, raising intracellular cAMP. The downstream effects most relevant here are increased hormone-sensitive lipase activity (lipolysis) and modest effects on cAMP-mediated steroidogenesis.

The most-cited trial is Godard 2005: 30 overweight or obese men randomised to 250 mg of a 10% forskolin extract twice daily vs placebo for 12 weeks, with measured body-composition changes (reduced fat mass, increased lean mass) and a modest rise in serum free testosterone. The Henderson 2005 trial in overweight women looked at body composition specifically; it did not isolate testosterone effects in men. Outside these, the chronic-dosing T literature in healthy or eugonadal men is sparse.

Dose: 250 mg of a 10% standardised extract, twice daily (effectively 50 mg total forskolin/day).

Tolerability: Headache, low blood pressure (vasodilation via cAMP/PKA pathway), tachycardia, and flushing. Forskolin is a potent vasoactive molecule.

Safety: Avoid in active hypotension, on antihypertensive medication without monitoring, or with antiplatelet/anticoagulant therapy (additive bleeding risk). Avoid in pregnancy and breastfeeding.

Ashwagandha (Withania somnifera) — strong adjacent evidence, smaller direct T effect

Ashwagandha's primary signal is on cortisol, perceived stress, and vitality scores rather than on raw testosterone elevation. Where T does move, it appears to move via reversing stress-induced suppression rather than via direct androgen stimulation.

The 2015 Wankhede trial in 57 untrained men randomised to 600 mg/day KSM-66 extract plus resistance training for 8 weeks found significant strength gains, muscle hypertrophy, and a modest serum testosterone increase. The 2019 Lopresti aging-male trial (43 men, 21–70 years, 8 weeks of 600 mg/day Shoden extract) reported a small testosterone increase and reductions in fatigue and DHEA-S effects. The 2019 Salve trial documented cortisol reductions in healthy adults. The 2013 Ambiye pilot in oligospermic males found sperm-quality improvements at 675 mg/day root extract for 90 days.

Dose: 600 mg/day of a standardised extract (KSM-66 or Shoden are the trial-validated brands). Once-daily or twice-daily dosing both work in published trials.

Tolerability: Generally well-tolerated. Drowsiness in some users at higher doses; GI upset uncommon.

Safety: Rare hepatotoxicity case reports — discontinue if jaundice, dark urine, or RUQ pain develops. Avoid in pregnancy and active hyperthyroidism (ashwagandha modestly raises thyroid hormones). Caution with sedatives and immunosuppressants.

Head-to-head matrix

PropertyTongkat aliFadogiaForskolinAshwagandha
Human RCTs (published, placebo-controlled)MultipleNoneFew, smallMultiple
Total testosterone effect (mean)Small-to-moderateNot human-validatedModest free-T signalSmall
Primary mechanism (claimed)SHBG-bound to free shift; cortisol modulationLH-mediated Leydig stimulation (rodents)cAMP-mediated lipolysis & steroidogenesisHPA axis modulation; cortisol reduction
Effective dose200–400 mg/day PhystaNot established in humans250 mg 10% extract bid600 mg/day standardised
Time to subjective effect4–12 weeks—8–12 weeks (mostly body comp)4–8 weeks
Cost per day$0.50–1.50$0.40–1.00$0.30–0.80$0.20–0.60
Safety in active prostate / hormone-sensitive cancerAvoidUnknownAvoid (data limited)Avoid
PregnancyAvoidAvoidAvoidAvoid
Evidence-quality call-out. Per SupplementScore tiers in data.js: tongkat ali sits at Tier B for testosterone-deficient or aging men; ashwagandha at Tier B for stress/cortisol and Tier C for testosterone-specific endpoints; forskolin at Tier C for body composition and Tier D for testosterone; fadogia agrestis at Tier D-weak (rodent-only efficacy, no human RCTs, limited human safety data). Industry-funded studies are concentrated in the tongkat ali and ashwagandha Physta/KSM-66 trial sets — see source funding notes below.

Which should you pick — decision tree

Practical rule. If you haven't measured your total and free testosterone twice on morning fasting draws, you don't know if you have a testosterone problem. The biggest mistake in this category is treating fatigue, low libido, or poor sleep with a T-claim supplement when the actual driver is sleep deprivation, undiagnosed depression, or sub-optimal training/nutrition.

Common misconceptions

Myth 1: "Tongkat + fadogia is the trial-validated stack." The "stack" is podcast-validated, not trial-validated. There are no published human RCTs of the combined product at the popularised doses. The tongkat half has evidence on its own; the fadogia half does not.

Myth 2: "Ashwagandha raises testosterone meaningfully in healthy young men." The signal in eugonadal young men is small. The clearer effects are on perceived stress and modest strength gains in untrained subjects under training. Don't expect TRT-class numbers.

Myth 3: "Forskolin is a testosterone booster." The Godard signal is on body composition primarily, with a smaller free-T move that has not been broadly replicated. Calling it a T-booster overstates a body-composition trial.

Myth 4: "Higher doses are more effective." The published RCTs cluster at narrow dose bands (tongkat 200–400 mg, ashwagandha 600 mg, forskolin 250 mg of 10% extract bid). Higher doses are not validated and increase the risk of side effects.

Myth 5: "These supplements can replace TRT for clinically low T." They cannot. Clinically diagnosed hypogonadism is an endocrinology problem with established treatments. Supplements may help at the margins for low-normal T or for stress-related suppression.

Who should not use any of these

Anyone with active prostate cancer, breast cancer, or other hormone-sensitive cancer should not use testosterone-modulating supplements without oncology input. Anyone under 25 with developing endocrine systems should avoid this category outside a clinician-supervised reason. Pregnant or breastfeeding women should avoid all four. People on antihypertensives, anticoagulants, immunosuppressants, or sedatives should review interactions before adding any of these, especially forskolin and ashwagandha.

What we'd actually buy

For a 40-something man with low-normal labs, normal liver and thyroid, no medication interactions, and a real interest in this category: a 12-week trial of tongkat ali 200–400 mg/day standardised extract, taken AM, with morning-fasting labs before and after. If stress is the obvious driver instead, swap in ashwagandha 600 mg/day KSM-66 or Shoden. Skip fadogia until there is human evidence. Save forskolin for the body-composition use case where the lipolytic mechanism is doing actual work.

None of these recommendations are sponsored. Verified-tested brand options are listed on each supplement's individual page.

Sources

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