Double Wood Horny Goat Weed (20% Icariins, 1000 mg) Review

Roughly 200 mg. Double Wood standardises to 20% icariins at a 1000 mg serving (two capsules), so 20% of 1000 mg is about 200 mg of icariins per day — a clearly-disclosed, well-dosed amount. That's lower in percentage terms than Toniiq's 40% or Nootropics Depot's minimum 50%, but it's delivered at a much larger total serving, so the raw icariin amount is competitive. The key point is that Double Wood tells you both numbers plainly, which lets you do this math — far better than a blend that hides the icariin content entirely.

Per the listing, Double Wood manufactures in cGMP facilities and runs third-party testing for identity and potency plus heavy metals — specifically lead, cadmium, arsenic and mercury. That heavy-metal panel matters for any botanical extract, since plants can concentrate soil metals, and it's one of the more complete testing disclosures in this category. We credit it as stated. Combined with the single-herb, no-filler formula, it's the main reason this is our best tested-value pick.

No — be clear-eyed here. A well-dosed 20% extract gives you a solid amount of icariin, which is a PDE5 inhibitor in the test tube (Xin 2003, PMID 12646997), but no robust human trial shows standalone horny goat weed treats erectile dysfunction or reliably raises libido. Double Wood's strength is transparency and testing, not a proven clinical effect. Use it as a well-made traditional vitality tonic with a measured expectation; if erectile dysfunction is your actual concern, that's a clinician conversation, not a supplement purchase.

The 1000 mg serving is split across two capsules, so the 90-capsule bottle is 45 servings — about a month and a half at one serving a day. That's a shorter supply than a one-cap-per-serving value tub like Nutricost (180 servings). The trade-off is that two capsules let Double Wood deliver a full 1000 mg of standardised extract, which is the highest raw dose among the pure single-herb picks. If you'd rather have a longer, cheaper supply at a lower dose, Nutricost (#5) or Swanson (#6) are the value alternatives.

Double Wood does market it heavily toward men, but epimedium is a traditional tonic used by both men and women, and the formula itself is just standardised single-herb extract with no sex-specific ingredients. So the marketing is louder than the formula warrants — there's nothing in the capsule that makes it men-only. As always, it isn't suitable in pregnancy or breastfeeding, and anyone with a hormone-sensitive condition should get individual medical advice given Epimedium's mild phytoestrogenic activity.

1. [1] Xin 2003 PMID 12646997 — Effects of icariin on cGMP-specific PDE5 and cAMP-specific PDE4 activities. In vitro, icariin inhibited cGMP-specific PDE5 with an IC50 of 0.432 µmol/L. The mechanistic basis for the herb's reputation and Double Wood's ~200 mg icariin serving — but a bench/enzyme finding, not proof of a human erectile-function benefit.
2. [2] Zhang 2007 PMID 17419678 — Epimedium-derived phytoestrogen flavonoids exert beneficial effect on preventing bone loss in late postmenopausal women: a 24-month randomized, double-blind and placebo-controlled trial. 60 mg/day icariin preserved bone mineral density over 24 months in postmenopausal women — the strongest human RCT for Epimedium, and a bone outcome rather than a sexual one. Cited to keep expectations for a well-dosed extract calibrated to the actual evidence.