Short answer: the formulas differ in which ingredient leads them. Testosil leads with KSM-66 Ashwagandha at the dose used in published research. TestoPrime and Prime Male spread across more ingredients. Nugenix leads with fenugreek. TestoFuel leads with D-aspartic acid.
| Testosil | TestoPrime | Nugenix | Prime Male | TestoFuel | |
|---|---|---|---|---|---|
| Lead ingredient | KSM-66 Ashwagandha | Broad blend | Fenugreek | Broad blend | D-aspartic acid |
| KSM-66 at studied dose | Yes | No | No | No | No |
| Absorption enhancer | AstraGin | No | No | No | No |
| Lifetime guarantee | Yes | No | No | No | No |
| Active ingredients | 11 | 12 | 8 | 12 | 9 |
| Typical price per month | $49 to $69 | $50 to $65 | $40 to $70 | $60 to $75 | $55 to $65 |
Based on publicly listed formulas and guarantee terms as of October 2026. Prices move often and are set by each manufacturer.
Most of these products share ingredients. Zinc, magnesium, vitamin D3 and fenugreek show up on nearly every label. Comparing ingredient counts is close to meaningless, because a formula with 12 ingredients at token amounts does less than a formula with 11 at researched amounts.
The question worth asking is which ingredient the formula is built around, and whether it is dosed the way the research dosed it.
Built on KSM-66 Ashwagandha at 600mg, matching the amount used in the 8 week study that produced the 434% figure.* Adds AstraGin so the rest is absorbed.
A broad formula with many inputs. Includes ashwagandha, but a different extract rather than the standardized KSM-66.
Built on Testofen, a fenugreek extract. Widely available in retail, which is convenient but means a different supply model.
Broad formula marketed to men over 40, with a higher price point and no single lead ingredient.
Ashwagandha is the ingredient in this category with the strongest human trial behind it. In an 8 week double blind placebo controlled study of 57 men aged 18 to 50, the group doing resistance training plus 300mg of the extract twice daily increased testosterone by 96.2 ng/dL. The group doing the same training with a placebo increased by 18.0 ng/dL, a difference significant at p=0.004.
Several competing products list ashwagandha. Fewer use the standardized KSM-66 extract, and fewer still use it at the full researched dose. That is the practical difference the table above is pointing at.
See the Testosil FormulaPricing and guarantee set by the manufacturer
Both are broad formulas at a similar price. The practical difference is that Testosil is built around KSM-66 Ashwagandha at the dose used in the published study, while TestoPrime includes ashwagandha as one of many inputs using a different extract. If the ashwagandha research is what you are buying for, Testosil matches it more closely.
Nugenix is built on Testofen, a fenugreek extract, and is sold in retail stores. Testosil is built on KSM-66 Ashwagandha at the researched dose and is sold direct by the manufacturer. The choice comes down to which ingredient you want leading the formula and whether retail availability matters to you.
Ashwagandha has the strongest human trial evidence of the common ingredients in this category, with an 8 week double blind placebo controlled study showing a 96.2 ng/dL testosterone increase versus 18.0 ng/dL for exercise alone. Products that use the standardized KSM-66 extract at the researched dose match that evidence most closely.
No. A formula with 12 ingredients at token amounts can do less than one with fewer ingredients at researched doses. What matters is which ingredient leads the formula and whether the amount matches what was studied.
Testosil carries a lifetime money back guarantee from its manufacturer, valid on direct orders. The other products listed have shorter or no comparable guarantee terms. Check each manufacturer for current terms.
Testosil: the full formula and the clinical study · What customers report · Full ingredient list and doses · Where to buy it
Daily Gear Digest covers supplements and performance products for men. Figures come from the clinical research the manufacturer cites and from the product label, with study conditions stated so you can judge them yourself. We earn a commission when you buy through our links, and we are not the manufacturer or seller of this product.
* In a clinical study of one ingredient, men taking that ingredient alongside exercise experienced a 434% greater increase in testosterone compared to men who exercised with a placebo, at a dosage equivalent to two servings of Testosil.
Medical disclaimer. These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. This page is for information only and is not medical advice. Consult a qualified healthcare provider before starting any supplement.
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Results disclaimer. Individual results vary. Study figures describe group averages under specific conditions including supervised resistance training, and are not a prediction of individual results.