Condition

Erectile Dysfunction

Erectile dysfunction is trouble getting or keeping an erection firm enough for sex, usually a blood-flow problem that depends on nitric oxide relaxing blood vessels. The evidence is strongest for Korean red ginseng, with moderate support for L-citrulline and L-carnitine, and in two small carnitine trials, erections went up. Those trials included only 147 men and paired carnitine with other treatments, so the findings are early.

Sources: PMID 15383186; PMID 21966881; PMID 21195829

Supplements studied: 9
Medicines and peptides: 1
Graded outcomes: 8
Trials: 12
People studied: 3,629

Evidence by supplement

Strong
Moderate
Limited
Very limited

9 supplements

L-Carnitine

L-Carnitine: outcomes studied for Erectile Dysfunction
Grade	Outcome	Effect	Size	Studies	People
	Erections Small Increase	Improves (the measure goes up)	Small effect	2 studies	147 people
Studies that measured erections Preliminary observations on the use of propionyl-L-carnitine in combination with sildenafil in patients with erectile dysfunction and diabetesCurr Med Res Opin · PMID 15383186 Propionyl-L-carnitine, L-arginine and niacin in sexual medicine: a nutraceutical approach to erectile dysfunctionAndrologia · PMID 21966881
	Sexual Function	Improves (the measure goes up)		1 study	96 people
Studies that measured sexual function Acetyl-L-carnitine plus propionyl-L-carnitine improve efficacy of sildenafil in treatment of erectile dysfunction after bilateral nerve-sparing radical retropubic prostatectomyUrology · PMID 16286128

Saffron

Saffron: outcomes studied for Erectile Dysfunction
Grade	Outcome	Effect	Size	Studies	People
	Depression Symptoms Moderate Improvement	Improves (the measure goes down)	Moderate effect	18 studies	30 people
Studies that measured depression symptoms Crocus Sativus L. (saffron) versus sertraline on symptoms of depression among older people with major depressive disorders-a double-blind, randomized intervention studyPsychiatry Res · PMID 31669837 Saffron improved depression and reduced homocysteine level in patients with major depression: A Randomized, double-blind studyAvicenna J Phytomed · PMID 29387573 Crocus sativus L. (petal) in the treatment of mild-to-moderate depression: a double-blind, randomized and placebo-controlled trialPhytomedicine · PMID 16979327 and 15 more on the Saffron page
	Erections	Improves (the measure goes up)		4 studies	387 people
Studies that measured erections Effects of a Topical Saffron (Crocus sativus L) Gel on Erectile Dysfunction in Diabetics: A Randomized, Parallel-Group, Double-Blind, Placebo-Controlled TrialJ Evid Based Complementary Altern Med · PMID 25948674 A systematic review and meta-analysis of clinical trials on saffron (Crocus sativus) effectiveness and safety on erectile dysfunction and semen parameters.Avicenna J Phytomed · PMID 29881706 Evaluation of Crocus sativus L. (saffron) on male erectile dysfunction: a pilot studyPhytomedicine · PMID 19427775 and 1 more on the Saffron page
	Sexual Function	Improves (the measure goes up)		2 studies	387 people
Studies that measured sexual function Saffron for treatment of fluoxetine-induced sexual dysfunction in women: randomized double-blind placebo-controlled studyHum Psychopharmacol · PMID 23280545 Effects of saffron (Crocus sativus) on sexual dysfunction among men and women: A systematic review and meta-analysis.Avicenna J Phytomed · PMID 31516855
	Penile Girth	Improves (the measure goes up)			20 people

Tribulus Terrestris

Blood Pressure: improves
Erections: improves
Testosterone: improves

Tribulus Terrestris: outcomes studied for Erectile Dysfunction
Grade	Outcome	Effect	Size	Studies	People
	Blood Pressure Small Improvement	Improves (the measure goes down)	Small effect		180 people
	Erections	Improves (the measure goes up)		4 studies	1,023 people
Studies that measured erections Tribulus terrestris versus placebo in the treatment of erectile dysfunction and lower urinary tract symptoms in patients with late-onset hypogonadism: A placebo-controlled studyUrologia · PMID 30253697 Pilot Study on the Effect of Botanical Medicine (Tribulus terrestris) on Serum Testosterone Level and Erectile Function in Aging Males With Partial Androgen Deficiency (PADAM)J Sex Marital Ther · PMID 25849625 Dietary Supplements for Erectile Dysfunction: Analysis of Marketed Products, Systematic Review, Meta-Analysis and Rational Use.Nutrients · PMID 37686709 and 1 more on the Tribulus Terrestris page
	Testosterone	Improves (the measure goes up)		3 studies	210 people
Studies that measured testosterone Prospective Analysis on the Effect of Botanical Medicine (Tribulus terrestris) on Serum Testosterone Level and Semen Parameters in Males with Unexplained InfertilityJ Diet Suppl · PMID 27337519 Short term impact of Tribulus terrestris intake on doping control analysis of endogenous steroidsForensic Sci Int · PMID 18282674 The aphrodisiac herb Tribulus terrestris does not influence the androgen production in young menJ Ethnopharmacol · PMID 15994038
	Low-density lipoprotein (LDL)	Improves (the measure goes down)		1 study	180 people
Studies that measured low-density lipoprotein (ldl) Efficacy of Tribulus Terrestris Extract on the Serum Glucose and Lipids of Women with Diabetes MellitusIran J Med Sci · PMID 27840471
	Free Testosterone	Improves (the measure goes up)			180 people
	High-density lipoprotein (HDL)	Improves (the measure goes up)			180 people
	Liver Enzymes	Changes; see studies			70 people
	Luteinizing Hormone	Improves (the measure goes up)			30 people
	Prostate-Specific Antigen	Improves (the measure goes up)			70 people
	Serum DHEA	Improves (the measure goes up)			180 people
	Sex Hormone Binding Globulin	Improves (the measure goes up)			180 people
	Total cholesterol	Improves (the measure goes down)			180 people
	Triglycerides	Improves (the measure goes down)			180 people

Maca

Erections: improves
Follicle-Stimulating Hormone: improves
Testosterone: improves

Maca: outcomes studied for Erectile Dysfunction
Grade	Outcome	Effect	Size	Studies	People
	Erections Small Increase	Improves (the measure goes up)	Small effect		50 people
	Follicle-Stimulating Hormone	Improves (the measure goes up)		3 studies	50 people
Studies that measured follicle-stimulating hormone Effect of Lepidium meyenii (Maca), a root with aphrodisiac and fertility-enhancing properties, on serum reproductive hormone levels in adult healthy menJ Endocrinol · PMID 12525260 Effect of Lepidium meyenii Walp. on Semen Parameters and Serum Hormone Levels in Healthy Adult Men: A Double-Blind, Randomized, Placebo-Controlled Pilot StudyEvid Based Complement Alternat Med · PMID 26421049 Subjective effects of Lepidium meyenii (Maca) extract on well-being and sexual performances in patients with mild erectile dysfunction: a randomised, double-blind clinical trialAndrologia · PMID 19260845
	Testosterone	Improves (the measure goes up)		1 study	50 people
Studies that measured testosterone Effect of Lepidium meyenii (MACA) on sexual desire and its absent relationship with serum testosterone levels in adult healthy menAndrologia · PMID 12472620
	Luteinizing Hormone	Improves (the measure goes up)			50 people
	Prolactin	Improves (the measure goes up)			50 people
	Subjective Well-Being	Improves (the measure goes up)			50 people

Nicotine

Blood Pressure
Libido: improves
Heart Rate: improves

Nicotine: outcomes studied for Erectile Dysfunction
Grade	Outcome	Effect	Size	Studies	People
	Blood Pressure No effect		NoneNo effect	2 studies	28 people
Studies that measured blood pressure Nicotine treatment of mild cognitive impairment: a 6-month double-blind pilot clinical trialNeurology · PMID 22232050 Acute effects of nicotine on physiological and subjective sexual arousal in nonsmoking men: a randomized, double-blind, placebo-controlled trialJ Sex Med · PMID 17971108
	Libido	Improves (the measure goes up)		1 study	28 people
Studies that measured libido The inhibitory effects of nicotine on physiological sexual arousal in nonsmoking women: results from a randomized, double-blind, placebo-controlled, cross-over trialJ Sex Med · PMID 18331269
	Heart Rate	Improves (the measure goes down)			28 people
	Penile Girth	Improves (the measure goes up)			28 people

Velvet Antler

Follicle-Stimulating Hormone
Testosterone: improves
Free Testosterone: improves

Velvet Antler: outcomes studied for Erectile Dysfunction
Grade	Outcome	Effect	Size	Studies	People
	Follicle-Stimulating Hormone No effect		NoneNo effect	1 study	24 people
Studies that measured follicle-stimulating hormone Effect of deer velvet on sexual function in men and their partners: a double-blind, placebo-controlled studyArch Sex Behav · PMID 12807299
	Testosterone	Improves (the measure goes up)		1 study	24 people
Studies that measured testosterone Effect of elk velvet antler supplementation on the hormonal response to acute and chronic exercise in male and female rowersInt J Sport Nutr Exerc Metab · PMID 16286669
	Free Testosterone	Improves (the measure goes up)			24 people
	Libido	Improves (the measure goes up)			48 people
	Luteinizing Hormone	Improves (the measure goes up)			24 people
	Prolactin	Improves (the measure goes up)			24 people
	Sexual Function	Improves (the measure goes up)			24 people

Panax Ginseng (Korean Ginseng)

Erections: improves

Panax Ginseng (Korean Ginseng): outcomes studied for Erectile Dysfunction
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Erections	Improves (the measure goes up)		4 studies	86 people
Studies that measured erections A double-blind crossover study evaluating the efficacy of korean red ginseng in patients with erectile dysfunction: a preliminary reportJ Urol · PMID 12394711 Clinical efficacy of Korean red ginseng for erectile dysfunctionInt J Impot Res · PMID 8750052 Study of the efficacy of Korean Red Ginseng in the treatment of erectile dysfunctionAsian J Androl · PMID 16855773 and 1 more on the Panax Ginseng (Korean Ginseng) page

Citrulline

Erections: improves

Citrulline: outcomes studied for Erectile Dysfunction
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Erections	Improves (the measure goes up)		1 study	24 people
Studies that measured erections Oral L-citrulline supplementation improves erection hardness in men with mild erectile dysfunctionUrology · PMID 21195829

Tongkat Ali

Erections: improves

Tongkat Ali: outcomes studied for Erectile Dysfunction
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Erections	Improves (the measure goes up)		1 study	128 people
Studies that measured erections Efficacy of Tongkat Ali (Eurycoma longifolia) on erectile function improvement: systematic review and meta-analysis of randomized controlled trials.Complement Ther Med · PMID 26365449

Prescription medicines and peptides studied, for context

These are not supplements. Most need a prescription, and some are research compounds with no approved use. They are listed so the supplement evidence above can be read against them.

1 medicine or peptide

PT-141 (Bremelanotide)

Erectile Function (ED Patients): improves
Erectile Response: improves

PT-141 (Bremelanotide): outcomes studied for Erectile Dysfunction
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Erectile Function (ED Patients) PT-141 was effective in Viagra-responsive ED patients, demonstrating a central mechanism distinct from PDE5 inhibitors.	Improves (the measure goes up)	Moderate effect	36 studies
	Erectile Response In Phase 1 studies, intranasal PT-141 induced statistically significant erectile responses in healthy males and ED patients at doses >7mg, with onset in approximately 30 minutes.	Improves (the measure goes up)	Moderate effect	34 studies

Key findings

ErectionsL-CarnitineImproves (the measure goes up)
Depression SymptomsSaffronImproves (the measure goes down)
Blood PressureTribulus TerrestrisImproves (the measure goes down)

The Erectile Dysfunction protocol

2 primary supplements · 5 supporting supplements

L-Citrulline1.5–3 g daily
Panax Ginseng (Korean Red Ginseng)900–1,800 mg daily

See the full protocol

Shop the evidence-backed picks

Fullscript collectionMen's health: evidence-graded picksOpen on Fullscript

The collection holds the supplements we grade A or B for its theme, in third-party tested products where the catalog has them. It opens in our Fullscript store. You can look through it without signing in; Fullscript asks for a free account to order.

Or shop one supplement

The supplement graded A or B for Erectile Dysfunction. Each opens third-party tested products for that supplement.

Grade B

We earn from purchases made in our Fullscript store, and links to Fullscript, iHerb or Thorne carry our referral, so we may earn a commission at no extra cost to you. Grades come from the research and never change based on what we earn. Full disclosure

Studies cited

1 study from PubMed

Antioxidant Supplementation for Erectile Dysfunction: Systematic Review and Meta-Analysis of Double-Blind, Randomized, Placebo-Controlled Trials.World J Mens Health · PMID 38772539