TCM Properties

Traditional Use

Tonifies Kidney Yang and replenishes Essence — primary tonic for Yang deficiency
Strengthens sinews and bones — treats Kidney-deficient weakness, soreness, and numbness
Dispels Wind-Cold-Dampness and relieves Bi syndrome joint pain
Warms and unblocks Yang — used for impotence, infertility, and cold uterine patterns

Anti-osteoporotic — improves bone mineral density; used in post-menopausal bone loss
Aphrodisiac — classical reputation supported by PDE5-inhibitory activity of icariin

Zan Yu Dan (赞育丹) — classic formula for male infertility and Kidney Yang deficiency; Yin Yang Huo combined with Ba Ji Tian, Du Zhong, She Chuang Zi
Er Xian Tang (二仙汤) — modern formula for menopausal syndrome; Yin Yang Huo combined with Xian Mao, Huang Bai, Zhi Mu, Dang Gui, Ba Ji Tian — balances Kidney Yang and Yin

Shen Nong Ben Cao Jing: lists Yin Yang Huo (also called Xian Ling Pi 仙灵脾) for strengthening Yang Qi, benefiting sinews and bones, and treating male sexual dysfunction
Ben Cao Gang Mu (Li Shizhen): 'Yin Yang Huo warms Kidney Yang, disperses Cold-Dampness from the sinews and bones, strengthens the will, and increases vital capacity — named because rams eating the herb mated excessively'

Icariin (principal prenylated flavonoid; 8-isopentenyl flavonoid; PDE5 inhibitor IC50 5.9 μM)
Icariside I and icariside II (icariin metabolites; PDE5 inhibition)
Icaritin (flavonoid aglycone; estrogenic and anticancer activity)
Epimedin A, B, C (flavonoid glycosides)
Kaempferol and quercetin glycosides
Polysaccharides (immune modulation)

Bone metabolism / anti-osteoporosis: icariin and icariside II promote osteoblast differentiation and inhibit osteoclast activity via BMP-2/Wnt/β-catenin pathways; human and animal studies confirm improvement in bone mineral density and biomechanical properties — primary evidence base for menopausal bone loss application
Erectile dysfunction: icariin inhibits PDE5A1 (IC50 5.9 μM) in vitro, increasing cGMP and promoting smooth muscle relaxation — mechanism identical to sildenafil/tadalafil; network pharmacology confirms PTGS2, NOS3, and AR as key targets for ED treatment (PMID 33368466)
Estrogenic/aromatase activity: icariin promotes CYP19 (aromatase) biosynthesis and upregulates estrogen receptor expression; raises bone estrogen signalling — use with caution in hormone-sensitive conditions and with aromatase inhibitor medications (PMID 23261485)

Yin deficiency with Heat signs (night sweats, afternoon fever, dry mouth, red tongue without coat)
Excess Heat patterns
Hormone-sensitive conditions (breast cancer, uterine cancer, endometriosis) — estrogenic activity

Standard dose 6–15g decoction
Prolonged use may induce CYP3A4 via pregnane X receptor activation — potential reduced efficacy of CYP3A4-metabolised drugs (immunosuppressants, statins, antivirals) with extended use
Aromatase inhibitors: icariin promotes aromatase (CYP19) activity — may reduce efficacy of anastrozole, exemestane, and letrozole in breast cancer treatment
PDE5 inhibitors (sildenafil, tadalafil, vardenafil): additive pharmacodynamic effect; avoid concurrent use — herb-drug interaction documented in animal PK study (PMC6270200)

Aromatase inhibitors (anastrozole, exemestane, letrozole): icariin promotes aromatase activity — potential reduction in drug efficacy in estrogen-sensitive cancer treatment
PDE5 inhibitors (sildenafil, tadalafil): pharmacodynamic additive effect via shared cGMP pathway; potential for enhanced hypotensive effect
CYP3A4 substrates: prolonged Epimedium use may induce CYP3A4 — reduced plasma levels of narrow-therapeutic-index CYP3A4 drugs possible with extended use