Both are 4-capsule testosterone support formulas built around D-aspartic acid and KSM-66 ashwagandha. The differences are in the doses and the extras.
Testosil and Testogen are similar in several ways: both give about 2 grams of D-aspartic acid and 4,000 IU of vitamin D per 4-capsule serving. Testosil has more KSM-66 ashwagandha (300 mg vs 200 mg), more zinc and ginseng, plus L-arginine and garlic. Testogen has twice the fenugreek, adds boron, nettle, vitamin K2 and copper, and keeps zinc at a more comfortable 25 mg. Neither has been tested as a finished product in a clinical trial.
Below are the amounts per 4-capsule serving. Testogen's figures come from the supplement facts on testogen.com, checked in October 2026. Testosil's supplement facts on its site are an image, so we used the label amounts from the Certificate of Analysis Testosil links from its homepage (Dyad Labs, April 2024).
| Ingredient | Testosil | Testogen |
|---|---|---|
| D-aspartic acid | 2,000 mg | 2,025 mg |
| KSM-66 ashwagandha | 300 mg | 200 mg |
| Fenugreek seed extract | 50 mg | 100 mg |
| Asian / Korean ginseng (Panax ginseng) | 180 mg | 100 mg |
| Stinging nettle root | None | 80 mg |
| L-arginine HCl | 250 mg | None |
| Garlic extract | 24 mg | None |
| Absorption aid | AstraGin, 10 mg | BioPerine (black pepper), 7 mg |
| Zinc | 40 mg | 25 mg |
| Magnesium | 50 mg | 100 mg |
| Vitamin D3 | 100 mcg (4,000 IU) | 100 mcg (4,000 IU) |
| Vitamin B6 | About 5.6 mg | 8 mg |
| Vitamin B5 (pantothenate) | 8 mg | None |
| Vitamin K2 (MK-7) | None | 90 mcg |
| Boron | None | 5 mg |
| Copper | None | 0.5 mg |
| Recommended use | 1 to 2 servings a day | 1 serving a day (2 capsules with breakfast, 2 with lunch) |
One caveat on Testosil: the certificate covers a 2023 batch, so check the label on your bottle in case the formula has changed.
KSM-66 is the ingredient with the best testosterone data in either formula. In Wankhede et al. (2015), 57 men aged 18 to 50 on a resistance training program took 300 mg twice a day or placebo for 8 weeks. Testosterone rose about 96 ng/dL on ashwagandha versus 18 ng/dL on placebo, though the extract was supplied by its manufacturer and the trial was small.
Testosil's 300 mg matches one of the two daily doses in the KSM-66 study, and two servings would match the full 600 mg. 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. Testogen's 200 mg is lower than the studied amount.
Both give about 2 grams. The evidence here is weak. A 2015 trial in 24 resistance-trained men found 3 g a day had no effect on testosterone over two weeks, and 6 g a day actually lowered it. Since the doses are practically identical and neither has strong support, we would not choose between them on this ingredient.
The best-known fenugreek trial (Rao et al. 2016) gave 600 mg a day of a standardized extract to 120 men aged 43 to 70 for 12 weeks and reported higher testosterone and better scores on aging-male symptoms. It was funded by the extract's maker. Testogen's 100 mg is a sixth of that dose and Testosil's 50 mg is a twelfth, so expect little from fenugreek in either.
Both give 4,000 IU of vitamin D, a high daily dose. Testosil's 40 mg of zinc is also on the high side, while Testogen's 25 mg is more moderate. That matters if you take a multivitamin, or if you follow Testosil's option of two servings a day, which doubles both. Testogen also adds a little copper, since zinc and copper compete for absorption. Our Testosil side effects guide covers the upper limits in detail.
Testogen includes boron, nettle root and vitamin K2. These have limited and mixed evidence for testosterone, so think of them as small bonuses rather than reasons to buy. Testosil's L-arginine and garlic are aimed more at blood flow than testosterone, and at these doses their effect is likely minor. If you want a broader framework for judging formulas like these, our guide on how to choose a testosterone supplement walks through what to look for.
| Testosil | Testogen | |
|---|---|---|
| One month | About $69 | About $70 |
| Larger packs | 3 bottles about $177, 6 bottles about $294 | 3 bottles about $140, 5 bottles about $210 |
| Guarantee | "Lifetime": refund on unopened bottles plus one opened bottle, shipping excluded, one order per customer | 100 days: refund on unopened bottles plus one opened bottle |
| Seller | Leading Edge Health (Canada, Cyprus, U.S. addresses listed) | No company name or address shown on testogen.com |
Prices are as of October 2026 and change often. When we checked, Testogen's packages were listed as out of stock. Both guarantees refund only one opened bottle, so neither lets you try six bottles and get all your money back. Testosil's has no time limit, which is the more generous term, though its guarantee page has some inconsistent wording, so confirm the details before returning anything.
Testosil also publishes a third-party lab certificate showing its batch matched the label and tested negative for hidden drugs such as sildenafil and SARMs. We did not find an equivalent certificate on testogen.com.
Because the core ingredients overlap, the safety profile is similar. Both contain ashwagandha, which has been linked to rare liver injury and changes in thyroid hormone levels, and which may interact with diabetes, thyroid, blood pressure, sedative and immunosuppressant medicines. Both contain ginseng and fenugreek, which can lower blood sugar. Testosil's higher ashwagandha dose and its garlic content (which may raise bleeding risk with blood thinners) give it slightly more to think about.
Men with hormone-sensitive prostate cancer, liver disease or thyroid conditions should talk to a doctor before taking either. We cover Testosil's risks in more detail in our guide to Testosil side effects.
If you are also weighing a formula without D-aspartic acid at its core, see our Testosil vs TestRX comparison.
These are two similar products. Testosil's main advantage is a higher dose of KSM-66 ashwagandha, the ingredient with the most testosterone research, plus a longer guarantee and a published lab test. Testogen's advantages are a gentler zinc dose, a bit more fenugreek and magnesium, and some extra micronutrients.
Neither has been tested in its own clinical trial, so the honest expectation is a modest effect at best, mostly from ashwagandha and from fixing any vitamin D or zinc shortfall. Neither is a treatment for low testosterone. For our full verdict on value, 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.