Each formula is aimed at men over 40, and each contains 300 mg of KSM-66 ashwagandha. After that, the two go in different directions.
KSM-66 ashwagandha (300 mg) and vitamin D (4,000 IU) per 4-capsule serving are the same in both. Testosil goes further on D-aspartic acid and zinc, includes fenugreek, L-arginine and garlic, and backs itself with a lifetime refund policy. Prime Male has no fenugreek. It brings luteolin, nettle root, boron and vitamin K2 instead, with less zinc, and its official returns policy applies only to unopened products within 30 days. No clinical trial has been run on either one.
Testosil comes from Leading Edge Health, which gives offices in Victoria, British Columbia and Limassol, Cyprus, and names a processing company in Las Vegas. Prime Male, per its own website, is sold by Roar Ambition Ltd. That company is registered in England and Wales, is based in Leeds, UK, and markets a range of men's supplements under the Prime Male name. Full ingredient lists appear on both sites, and neither places its doses inside a proprietary blend.
A naming point: the main Prime Male formula is now called "Vitality" on its site. That is the product we are comparing.
Prime Male's amounts are from the supplement facts on primemale.com (checked October 2026). Because Testosil shows its supplement facts only as an image, we used the label amounts from the Certificate of Analysis linked on testosil.com (Dyad Labs, April 2024). All figures are for one 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 | Around 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 daily | 1 capsule four times daily, with food |
Keep two points in mind. Testosil's certificate is for a 2023 batch, so compare it with your own bottle's label in case the formula has changed. Prime Male's product page also contradicted itself when we looked in October 2026. The supplement facts show black pepper at 10 mcg and zinc at 25 mg, while the ingredient write-ups further down give 10 mg and 25 mcg. We used the supplement facts panel, which is usually the definitive version.
Both contain 300 mg of KSM-66, the ingredient with the best testosterone research in either formula. Wankhede et al. (2015) gave 57 men aged 18 to 50 either 300 mg twice a day or placebo for 8 weeks alongside resistance training. Testosterone rose about 96 ng/dL with ashwagandha and 18 ng/dL with placebo. The trial was small, the extract came from its maker, and most men were in their late 20s, so it says little about men over 40.
Testosil's label, however, permits up to two servings, bringing the total to 600 mg, which is the full daily dose studied. 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 holds to 300 mg a day.
Testosil supplies 2,000 mg of D-aspartic acid. Prime Male supplies 1,600 mg of a calcium-bound form, so the amount of actual D-aspartic acid is a bit lower. Either way the human evidence is weak. A 2015 trial of 24 resistance-trained men found that 3 g a day did nothing to testosterone over two weeks, while 6 g a day reduced it. Both products fall under 3 g, so this ingredient isn't a reason to choose one over the other.
Testosil has fenugreek. The best-known trial (Rao et al. 2016) gave 600 mg a day to 120 men aged 43 to 70 for 12 weeks and reported higher testosterone. The extract's maker funded it, and Testosil's 50 mg is one twelfth of that dose. We wouldn't expect much from it.
Prime Male takes another route, with nettle root, luteolin and boron. The main idea behind them is that they might help keep more testosterone in its free form or limit its conversion to estrogen. Human evidence at these doses is limited, so we see them as plausible extras and not proven benefits.
Both provide 4,000 IU of vitamin D, which is a high daily amount. Testosil's 40 mg of zinc is clearly above Prime Male's 25 mg. If you already use a multivitamin, or would take Testosil's two-serving option, Prime Male's lower zinc is the easier fit. Prime Male also has vitamin K2, which works with vitamin D in calcium handling.
To see how Testosil measures up against a different formula without some of these ingredients, read 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, or 6 bottles about $294 | 2 months about $150, or 4 months about $225 |
| Refund policy | "Lifetime" guarantee: refund covers unopened bottles and one opened bottle, with shipping excluded and one order per customer | Unused, unopened, sealed products can be returned within 30 days (U.S. and Canada) |
| Lab testing is shown | Third-party certificate posted, negative for hidden drugs | No certificate found on the site |
Prices date from October 2026, when Prime Male's site showed the product out of stock. Refunds are where the two differ most in practice. Testosil will refund one opened bottle without a time limit, although its guarantee page contains some inconsistent wording, so verify the terms beforehand. We could not find a satisfaction guarantee on primemale.com, and its returns page only applies to unopened products. If you want to try something and recover your money when it does nothing, Testosil's terms are clearly the more generous.
For more on the company, the lab certificate and the small print of the guarantee, see our article asking whether Testosil is legit.
Ashwagandha and ginseng are in both formulas, so the main cautions are shared. Rare liver injury and thyroid hormone changes have been linked to ashwagandha, and it may interact with diabetes, thyroid, blood pressure, sedative and immunosuppressant medicines. Men taking medicines for blood sugar, blood thinning or blood pressure have a bit more to consider with Testosil, because of its fenugreek, garlic and L-arginine.
Men with hormone-sensitive prostate cancer, liver disease or thyroid conditions should check with a doctor before taking either one. Our guide to Testosil side effects goes through each ingredient.
Where it matters most, they match: 300 mg of KSM-66 in each serving. Testosil adds more zinc and D-aspartic acid, has a published lab certificate and offers a much more generous refund policy. Prime Male uses less zinc, includes vitamin K2 and has different extras, which its maker says target free testosterone. Its returns policy covers unopened products.
Neither one has been tested as a finished product, and neither is a treatment for low testosterone. With symptoms, see a doctor and get your levels checked before anything else. Read the Testosil review for our complete verdict on Testosil.
Affiliate link: if you buy through it, we earn a commission, at no extra cost to you. The guarantee is advertised as a lifetime money-back offer. It refunds unopened bottles and one opened bottle, doesn't refund shipping, and allows one order per customer. Parts of the guarantee page are worded inconsistently, so check the terms with customer service before you send anything back.