Maca root and ashwagandha are two of the most searched-for natural ingredients for male libido, and the human evidence behind them doesn’t point the same direction. Maca’s best-supported finding is improved self-reported sexual desire at a specific dose, through a pathway that doesn’t appear to involve testosterone. Ashwagandha’s best-supported findings involve broader sexual-function scores alongside a measurable testosterone increase. Neither ingredient’s evidence is strong enough to replace a medical evaluation when a decline in libido is new, sudden, or paired with other symptoms — and that distinction matters more than which supplement aisle you start in.
This guide walks through what the human studies on each ingredient actually measured, at what dose, in whom, and for how long — kept separate, because a result from one ingredient’s trial doesn’t transfer to the other. It closes with a short worksheet you can fill out privately before a doctor’s visit, if that’s the next step that makes sense for you.
Maca Root: What the Human Studies Show
Maca (Lepidium meyenii) is a Peruvian root vegetable, traditionally eaten rather than taken as an isolated extract, which is part of why dosing across studies varies more widely than it does with a standardized botanical extract.
The most directly relevant trial for libido specifically is a 12-week, double-blind, placebo-controlled study of 57 healthy adult men aged 21–56, run in three arms: 1,500 mg per day of gelatinized maca (30 men), 3,000 mg per day (15 men), and placebo (12 men). The result is more specific than “maca helped”: the 1,500 mg/day arm showed a significant improvement in self-reported sexual desire versus placebo at both 8 and 12 weeks, while the 3,000 mg/day arm did not reach significance versus placebo at any point measured. In other words, more wasn’t better in this trial — the lower of the two doses is the one with the supported result. Separately, researchers checked whether the desire improvement tracked with changes in testosterone or estradiol, and it didn’t; hormone levels were statistically similar across the maca and placebo groups, which is the main reason maca is discussed as working through a non-hormonal pathway.
A separate double-blind, randomized trial looked at a different outcome: erectile function, not desire. Fifty men with mild erectile dysfunction took 2,400 mg per day of maca dry extract or placebo for 12 weeks. On the IIEF-5 erectile-function questionnaire, both groups improved significantly, with no meaningful difference between maca and placebo. Where maca did separate from placebo was on a subjective wellbeing scale (SAT-P), where the maca group’s psychological-performance score rose further than the placebo group’s. In plain terms: this trial did not show maca outperforming placebo for erectile function itself, only for how men felt about their overall sexual wellbeing.
That’s a meaningful limit, not a footnote — desire and erectile function are different outcomes, and the strongest maca evidence applies to the former, not the latter.
A third trial, a 28-day randomized study of 47 participants (22 men, 25 women), tested a patented maca extract blend at 2.1 g per day. Men in the maca group showed significant improvement in self-reported sexual function, handgrip strength, and reduced fatigue compared to placebo. Women’s scores improved versus their own baseline but not significantly versus placebo — another reminder that maca’s human evidence base currently shows clearer separation from placebo in men than in women.
Taken together: maca’s best-supported, dose-specific claim for men is improved self-reported sexual desire at 1,500 mg/day of gelatinized root over 8–12 weeks, via a pathway that doesn’t appear to run through testosterone or estradiol — a higher 3,000 mg/day dose did not outperform placebo in that same trial. Maca’s evidence for erectile function specifically is separate, weaker, and mixed.
Ashwagandha: What the Human Studies Show
Ashwagandha (Withania somnifera) is an adaptogenic herb most studied for stress and cortisol, with a smaller but growing body of research on male sexual function, typically using a standardized high-withanolide root extract (KSM-66 in both trials below) rather than whole-root maca-style dosing.
The first relevant trial is an 8-week, randomized, double-blind, placebo-controlled study of 50 adult men (average age 35) with low sexual desire, randomized 25 to ashwagandha and 25 to placebo. Men took one 300 mg KSM-66 capsule twice daily (600 mg/day total). Using the Derogatis Interview for Sexual Functioning–Male (DISF-M) as the primary measure, the ashwagandha group’s total score rose from 62.92 to 88.40 (about +40%), versus 61.08 to 76.76 on placebo (about +25%) — a statistically significant between-group difference. Serum testosterone rose from roughly 403 to 475 ng/dL in the ashwagandha group (about +17%) versus a non-significant change on placebo. Worth disclosing: several of this study’s authors reported consultation fees from the company that recruited volunteers for the trial, which doesn’t invalidate the data but is a relevant conflict-of-interest detail for anyone weighing how much confidence to place in it.
A second, separate 8-week randomized, double-blind, placebo-controlled trial tested the same 300 mg twice-daily KSM-66 dose in 93 healthy men, using the International Index of Erectile Function (IIEF) rather than the DISF-M. Reported improvements versus placebo included erectile function (+12.11%), orgasmic function (+19.03%), sexual desire (+31.53%), and intercourse satisfaction (+29%), alongside a 14.3% rise in testosterone. This is a different trial, in a larger group, using a different questionnaire, than the DISF-M study above — it’s supporting evidence for the same ingredient and dose, not a replication of the first study’s exact numbers.
One honest caveat worth stating plainly: sexual-health trials in general carry a well-documented placebo response, and smaller single trials in this category deserve a measured read rather than a confident one, even when results reach statistical significance.
Ashwagandha’s best-supported, dose-specific claim for men is improvement in self-reported sexual function and a double-digit percentage testosterone increase at 600 mg/day (300 mg twice daily) of standardized KSM-66 root extract over 8 weeks, in men who started with lower sexual desire, replicated across two separately published trials using that dose.
Why These Two Don’t Get Combined Into One Verdict
Maca’s strongest human signal is for desire, through a pathway that doesn’t appear to involve testosterone, and specifically at 1,500 mg/day rather than a higher dose. Ashwagandha’s strongest human signal is for broader sexual-function scores alongside a measurable testosterone increase, in different participant groups, using a different standardized extract, at a different total daily dose. No study reviewed here tested maca and ashwagandha together, so neither ingredient’s results can be borrowed to support a claim about the other, or about a combination of both — a blend has not been shown to add the two effects together, because that combination hasn’t been the subject of a human trial.
When Declining Libido Is Worth a Medical Visit, Not Just a Supplement
A gradual, lifelong, low sex drive is different from a libido that changed. According to the National Institute of Diabetes and Digestive and Kidney Diseases, erectile and sexual-function changes in men are frequently connected to underlying, treatable causes — cardiovascular disease, diabetes, low testosterone, certain medications, and mental health conditions among them — which is part of why a new or sudden change is worth a clinical conversation rather than a self-directed supplement trial alone. A qualified clinician can also test for and identify something a supplement simply can’t address.
It’s also worth knowing that the FDA has repeatedly identified sexual-enhancement products — sold as “all natural” dietary supplements — that secretly contain undeclared prescription drug ingredients, including sildenafil (the active ingredient in Viagra), tadalafil (the active ingredient in Cialis), or close chemical analogs of either. These hidden ingredients carry real risk, particularly for anyone taking nitrate medications, because the combination can cause a dangerous drop in blood pressure. This is a separate issue from the maca and ashwagandha evidence above — it’s a labeling and manufacturing-integrity problem specific to certain branded “male enhancement” products — but it’s a real reason to read labels carefully and buy from sources that disclose exactly what’s in the product.
Appointment-Prep Worksheet
If you’re planning to bring this up with a doctor, clinicians generally get to a useful answer faster when you walk in with specifics rather than “it’s just been off lately.” This worksheet is for your own private use; nothing on this page collects, stores, or transmits what you write.
Symptom pattern
- When did you first notice the change — gradual over months, or a clearer before/after?
- Is it desire, physical response, or both?
- Is it constant, or does it vary with stress, sleep, or specific situations?
Timeline
- How long has this been going on?
- Did it start around the same time as a medication change, a major stressor, a diagnosis, or a life event?
Current medicines and substances
- All prescription medications, including dose
- Any supplements already being taken, maca and ashwagandha included, with dose and how long
- Alcohol, nicotine, or recreational substance use, if relevant — clinicians need this to assess interactions, not to judge
Relevant health context
- Diagnosed conditions (cardiovascular, diabetes, thyroid, mental health)
- Recent bloodwork, if you have it, especially testosterone
- Sleep quality and stress levels over the past few months
Questions to bring
- Could any of my current medications be contributing to this?
- What bloodwork would help clarify what’s going on?
- Is there a reason to be cautious about maca or ashwagandha given my health history or medications?
- What would you consider a reasonable first step?
If you came to this page from our look at the pelvic-floor “erection muscle trick” and its accompanying herbal ingredients, that piece covers a different combination (L-arginine, tongkat ali, maca, and horny goat weed) aimed at circulatory and exercise-based support. This page is a standalone look at the maca-and-ashwagandha question specifically, not a continuation or product comparison — the next useful step from here is the label/evidence checklist above, not a purchase.