Testosil and Prime Male share the same core dose of KSM-66 ashwagandha (300 mg) and 4,000 IU of vitamin D per 4-capsule serving. Testosil adds more D-aspartic acid, more zinc, plus fenugreek, L-arginine and garlic, and offers a lifetime refund policy. Prime Male skips fenugreek but adds luteolin, nettle root, boron and vitamin K2, keeps zinc lower, and its official returns policy only covers unopened products within 30 days. Neither has been tested in its own clinical trial.
Testosil is sold by Leading Edge Health, which lists offices in Victoria, British Columbia and Limassol, Cyprus, plus a processing company in Las Vegas. According to its website, Prime Male is sold by Roar Ambition Ltd, a company registered in England and Wales and based in Leeds, UK, which sells a range of men's supplements under the Prime Male name. Both publish full ingredient lists on their sites, and neither puts doses inside a proprietary blend.
One note on naming: Prime Male's site now calls the main formula "Vitality." That is the product we compare here.
Prime Male's figures come from the supplement facts on primemale.com, checked in October 2026. Testosil's supplement facts are posted as an image, so we used the label amounts in the Certificate of Analysis linked from testosil.com (Dyad Labs, April 2024). Both are per 4-capsule serving.
| Ingredient | Testosil | Prime Male |
|---|---|---|
| KSM-66 ashwagandha | 300 mg | 300 mg |
| D-aspartic acid | 2,000 mg | 1,600 mg (as D-aspartic acid calcium chelate) |
| Panax ginseng | 180 mg | 120 mg (Korean ginseng) |
| Fenugreek seed extract | 50 mg | None |
| Nettle root extract | None | 160 mg |
| Luteolin | None | 60 mg |
| L-arginine HCl | 250 mg | None |
| Garlic extract | 24 mg | None |
| Absorption aid | AstraGin, 10 mg | Black pepper extract (label says 10 mcg) |
| Zinc | 40 mg | 25 mg |
| Magnesium | 50 mg | 100 mg |
| Vitamin D3 | 4,000 IU | 4,000 IU |
| Vitamin B6 | About 5.6 mg | 7.5 mg |
| Vitamin B5 | 8 mg | None |
| Vitamin K2 (MK-7) | None | 45 mcg |
| Boron | None | 5 mg |
| Directions | 1 to 2 servings a day | 1 capsule four times a day with food |
Two caveats. Testosil's certificate covers a 2023 batch, so check your bottle's label for any formula change. When we checked in October 2026, Prime Male's product page gave different figures in different places: the supplement facts list black pepper at 10 mcg and zinc at 25 mg, while the ingredient descriptions further down say 10 mg and 25 mcg. We used the supplement facts panel, which is normally the authoritative version.
Both use 300 mg of KSM-66, the ingredient with the strongest testosterone research in either formula. In Wankhede et al. (2015), 57 men aged 18 to 50 took 300 mg twice a day or placebo for 8 weeks while doing resistance training. Testosterone rose about 96 ng/dL on ashwagandha versus 18 ng/dL on placebo. It was a small trial, the extract was supplied by its maker, and the men were mostly in their late 20s, so it does not tell us much about men over 40.
The difference is that Testosil's label allows up to two servings, which would reach 600 mg, the full studied daily dose. Two servings would double zinc to 80 mg and vitamin D to 8,000 IU a day, twice the adult upper limits, so don't take two servings without a doctor's advice. Prime Male sticks to 300 mg a day.
Testosil gives 2,000 mg of D-aspartic acid. Prime Male gives 1,600 mg of a calcium-bound form, which means slightly less actual D-aspartic acid. Human evidence is weak either way. In a 2015 trial of 24 resistance-trained men, 3 g a day made no difference to testosterone over two weeks and 6 g a day lowered it. Both products are below 3 g, so we would not pick one over the other on this ingredient.
Testosil includes fenugreek. The best-known fenugreek trial (Rao et al. 2016) used 600 mg a day in 120 men aged 43 to 70 for 12 weeks and reported higher testosterone, but it was funded by the extract's maker and Testosil's 50 mg is a twelfth of that dose. Expect little from it.
Prime Male instead adds nettle root, luteolin and boron. These are included mainly on the theory that they may help keep more testosterone free or limit its conversion to estrogen. Human evidence for these at these doses is limited, so we treat them as plausible extras rather than proven benefits.
Both give 4,000 IU of vitamin D, a high daily dose. Testosil's 40 mg of zinc is noticeably higher than Prime Male's 25 mg. If you already take a multivitamin, or would follow Testosil's two-serving option, Prime Male's lower zinc is the more comfortable choice. Prime Male also includes vitamin K2, which works alongside vitamin D in calcium handling.
For a broader look at how Testosil compares with another formula that skips some of these ingredients, see our Testosil vs TestRX comparison, or our breakdown of Testosil vs Testogen.
| Testosil | Prime Male | |
|---|---|---|
| One month | About $69 | About $75 |
| Larger packs | 3 bottles about $177, 6 bottles about $294 | 2 months about $150, 4 months about $225 |
| Refund policy | "Lifetime" guarantee: refund on unopened bottles plus one opened bottle, shipping excluded, one order per customer | Returns accepted within 30 days (U.S. and Canada) for unused, unopened, sealed products |
| Lab testing shown | Third-party certificate posted, negative for hidden drugs | We did not find a certificate on the site |
Prices are as of October 2026. When we checked, Prime Male's site showed the product as out of stock. The refund gap is the biggest practical difference. Testosil will refund one opened bottle with no time limit, though its guarantee page has some inconsistent wording, so confirm terms first. We did not find a satisfaction guarantee on primemale.com, and its returns page only covers unopened products. If you want to try a product and get money back if it does nothing for you, Testosil's terms are clearly more generous.
Our article on whether Testosil is legit goes deeper into the company, the lab certificate and the guarantee fine print.
Both contain ashwagandha and ginseng, so they share the same main cautions. Ashwagandha has been linked to rare liver injury and changes in thyroid hormone levels, and may interact with diabetes, thyroid, blood pressure, sedative and immunosuppressant medicines. Testosil's fenugreek, garlic and L-arginine add a little more to consider for men on blood sugar, blood thinning or blood pressure medicines.
Men with hormone-sensitive prostate cancer, liver disease or thyroid conditions should talk to a doctor before taking either. Our guide to Testosil side effects covers the details ingredient by ingredient.
On the ingredient that matters most, these two are equal: both deliver 300 mg of KSM-66 per serving. Testosil has more zinc and D-aspartic acid, a published lab certificate and a much more generous refund policy. Prime Male has lower zinc, vitamin K2 and a different set of extras that its maker says target free testosterone, and Prime Male's returns policy covers unopened products.
Neither has been tested as a finished product, and neither is a treatment for low testosterone. If you have symptoms, get your levels checked by a doctor first. For our full verdict on Testosil, read our Testosil review.
Affiliate link: we earn a commission if you buy through it, at no extra cost to you. Advertised as a lifetime money-back guarantee: the refund covers unopened bottles plus one opened bottle; shipping isn't refunded; one order per customer. Some wording on the guarantee page is inconsistent, so confirm the terms with customer service before returning anything.