Butea Superba: Benefits, Side Effects and What Research Shows

Short answer: Butea superba (red kwao krua) is a Thai climbing vine whose tuberous root has a long folk reputation as a male vitality and aphrodisiac herb. Human evidence is thin: one small Thai trial reported improved erectile function scores, but it lost its placebo group, and a later comparison study ran into a contaminated batch. Animal studies show real androgenic activity, plus some safety signals (higher liver enzymes and lower testosterone at high doses, and DNA damage markers at very high doses). Low traditional doses appear tolerable based on limited data, but no one can yet say it is proven or fully safe.

Key Takeaways

• Butea superba is a vine in the legume family (Fabaceae), known in Thailand as red kwao krua and traditionally used there as a male tonic and aphrodisiac.^[1][6]
• The main human trial (Thailand, 2003) reported that 82.4% of men noticed improvement on a sexual record, but Examine.com downgrades it to a pilot because the placebo group dropped out.^[1][2]
• The herb acts like an androgen in animals. In rats, high doses raised liver enzymes (ALP and AST) and lowered serum testosterone, likely through hormonal feedback.^[1]
• At 1,000 mg/kg, a rodent study found a significant rise in micronuclei, a marker of genetic damage in bone marrow cells.^[3]
• Examine.com says there is not enough information to recommend supplementation; traditional use falls around 100 to 250 mg.^[1]
• Quality matters: one study batch was found to contain prescription PDE5 inhibitor drugs, a known problem in “male enhancement” herbal products.^[1]

What Is Butea Superba?

Butea superba Roxb. is a vining plant in the Fabaceae (pea and bean) family. In Thailand it is known as red kwao krua, and its tuberous root is the part used.^[6] The name matters because Thai markets also sell “white kwao krua,” which is a different plant (Pueraria mirifica) with mostly estrogen-like effects. Examine.com describes the two tubers as visually similar but working in roughly opposite directions.^[1]

Chemically, the root contains flavonoids and flavonoid glycosides.^[6] Early Thai laboratory work linked some of these flavonoids to inhibition of cAMP phosphodiesterase, an enzyme family involved in smooth muscle relaxation.^[6] Still, Examine.com notes that the exact compounds responsible for the herb’s hormonal effects are not yet known, and neither is their strength compared with testosterone.^[1]

Why it became a “men’s herb”

In Thai folk practice the red tuber was taken by men for vigor and sexual function. That reputation is what drew researchers, mostly from Thai universities, to study it from the late 1990s onward. Most of what we know comes from rats and mice, with only a few small human studies.

Butea Superba Benefits: What the Evidence Shows

When people search for Butea superba benefits, they are almost always asking about sexual function. Here is what the published research actually covers, with human and animal work kept separate.

Human studies

The 2003 Thai trial. Cherdshewasart and Nimsakul ran a 3 month study in Thai men aged roughly 30 to 70 with erectile difficulties, using a crude preparation of the tuber. They reported significant improvement in four of five domains of the IIEF-5 questionnaire, and 82.4% of participants showed noticeable improvement by sexual record estimate. Blood counts and blood chemistry showed no apparent change.^[2] The catch: Examine.com reports that the whole placebo group dropped out, leaving 17 men on the herb (500 mg of tuber extract daily), so the study is best viewed as a pilot with no real control group.^[1]

The 2010 comparison study. Cortés-González and colleagues published an open label study in which men taking 100 mg of Butea superba had better IIEF scores than men on a standard prescription drug.^[4] But when the team ran a double blind follow up with a different batch, the effect disappeared, and they reported that the first batch contained PDE5 inhibitor drugs, which produced a false positive.^[1] In other words, the most impressive human result appears to have come from adulteration, not the herb.

Examine.com’s overall verdict is that both human studies have flaws, and the herb is not proven to help erections.^[1] RxList likewise rates the evidence as insufficient for every use it lists.^[5]

Animal studies

• Androgenic activity: Examine.com summarizes the animal data as showing classic direct androgenic effects, including growth of male sex organs.^[1]
• Hormones: In a 30 day study in male rats, 10, 50 or 250 mg/kg per day did not change serum testosterone, LH or FSH in intact animals; seminal vesicle weight rose only at the highest dose. In castrated rats, LH fell at 50 and 250 mg/kg.^[6]
• Sperm: Long term animal studies reported higher sperm counts, with no sperm abnormalities or testicular damage at the doses tested.^[1]

Animal results tell researchers where to look. They do not tell you what a capsule will do in a person.

How Butea Superba Is Thought to Work

Two mechanisms come up most often in the literature:

1. Androgen-like signaling. Compounds in the root appear to act on androgen pathways directly. That explains the sex organ growth in animals, and also why the body may respond by producing less of its own testosterone (negative feedback).^[1]
2. Phosphodiesterase inhibition. Some isolated flavonoids inhibited cAMP phosphodiesterase in lab tests, which could in theory support smooth muscle relaxation in blood vessels.^[6] This is a test tube finding only.

The authors of the 2010 rat study also raised a third possibility: the LH drop they saw could be partly estrogenic (from phytoestrogens) rather than purely androgenic.^[6] The honest summary is that the mechanism is not settled.

Butea Superba Dosage: What Studies Used

There is no established safe or effective dose. Examine.com states there is not enough information to recommend supplementation, and that traditional use appears to fall in the 100 to 250 mg range.^[1] RxList also says there is not enough scientific information to set a dose range and advises following label directions and asking a healthcare professional.^[5] The table below shows doses from the research so you can see the context.

Animal doses per kilogram are far higher than a typical capsule, but Examine.com converts the mutagenic range to a human equivalent of about 48 mg/kg and above and advises against such doses.^[1]

Butea Superba Side Effects and Safety

This is where Butea superba differs from gentler herbs. Its effects on hormones are real enough to carry risk.

Hormonal effects

In rats, 150 to 200 mg/kg of root powder caused a dose dependent drop in serum testosterone.^[1] Researchers behind that 90 day study called the herb an androgen disruptor.^[6] Examine.com also describes a case report of a 35 year old man who took an unreported dose for a few weeks (for hair regrowth) and developed hyperandrogenemia, with DHT at 1,512 pg/mL. His levels normalized about a week after he stopped.^[1]

Liver and blood markers

Some animal studies reported increases in liver enzymes (ALP and AST) and spleen weight at higher doses.^[1] The small human trial did not see changes in blood chemistry,^[2] but it was short and small.

Genetic toxicity

A Thai toxicology study gave rodents 2, 20, 200 or 1,000 mg/kg per day. Only the 1,000 mg/kg group showed a significant increase in micronucleated red blood cells (0.271% versus 0.088% in controls) and signs of bone marrow suppression. The powder did not harm male germ cells in the dominant lethal test, but the authors warned that micronucleus formation was dose dependent, so higher doses could be toxic.^[3]

Adulteration

The 2010 batch contaminated with prescription drugs is a warning for the whole category. Products sold as “Thai herbal sex boosters” are a known target for hidden drugs. Choose brands that publish exact amounts and test their raw materials. Our guide to third-party tested supplements explains what to look for.

Who Should Avoid Butea Superba or Talk to a Doctor First

• Pregnant or breastfeeding women: not enough is known, so avoid it.^[5] Given its androgenic effects, women in general have little reason to take it.
• Men with liver disease or abnormal liver tests, because of the enzyme increases seen in animals.
• Men with hormone sensitive conditions or on hormone therapy (testosterone replacement, prostate treatment, hair loss drugs), because the herb acts on androgen pathways.
• Anyone with erection problems: erectile changes can be an early sign of heart disease, diabetes or other conditions, so see a clinician before trying any supplement. If you are wondering about hormones, our article on signs of low testosterone covers when blood testing makes sense.
• Anyone taking prescription medicines: interaction data are missing,^[5] so ask a pharmacist.

If you do use it, stay at modest doses, do not stack several androgenic products, and consider asking your doctor for liver and hormone blood work if you take it for months.

Butea Superba in Ultra Bann

Ultra Bann is a natural male vitality supplement by DL Bioproducts, taken as one capsule every 2 days. Each capsule lists seven botanicals with exact amounts and no proprietary blend: Thai Butea superba 345 mg, Panax ginseng 110 mg, Cynomorium songaricum 85 mg, black ginger (Kaempferia parviflora) 85 mg, tongkat ali 85 mg, epimedium (horny goat weed) 45 mg and reishi 45 mg, for 800 mg in total. Butea superba is the largest ingredient, so the safety points above apply: if you have liver issues, a hormone sensitive condition or take prescription medicine, check with your doctor first. You can read the full label on our ingredients page, and learn about two of the other botanicals in our guides to Panax ginseng for men and black ginger. First orders ship free in the US and come with a 60-day money-back guarantee; see the Ultra Bann shop.

Frequently Asked Questions

Does Butea superba actually work?

The evidence is weak. One small Thai trial reported better erectile function scores, but it lost its placebo group. A later positive study was traced to a batch containing prescription drugs. Examine.com concludes the herb is not proven as an erectile aid.^[1]

Does Butea superba increase testosterone?

Not according to current data. It acts like an androgen itself, and in rats high doses actually lowered serum testosterone, likely through negative feedback.^[1] In the human trial, the reported rise in testosterone was not statistically significant.^[1]

What is the difference between red and white kwao krua?

Red kwao krua is Butea superba, traditionally used by men. White kwao krua is Pueraria mirifica, a phytoestrogen rich plant used mainly by women. They look alike but have roughly opposite hormonal effects.^[1]

Is Butea superba safe to take every day?

Low traditional doses appear tolerable based on limited evidence, but long term human safety has not been studied. Animal studies flagged liver enzyme increases, lower testosterone and genetic damage markers at high doses.^[1][3] Talk to a doctor before long term use.

How long does Butea superba take to work?

The only controlled human trial ran for 3 months.^[2] There are no reliable data on how quickly any effect appears, so be skeptical of products promising results within hours, which can be a sign of hidden drugs.

References

1. Examine.com. Butea superba: supplement overview and research summaries. examine.com/supplements/butea-superba
2. Cherdshewasart W, Nimsakul N. Clinical trial of Butea superba, an alternative herbal treatment for erectile dysfunction. Asian Journal of Andrology. 2003;5(3):243-6. PMID 12937809. PubMed
3. Pongpanparadon A, Aritajat S, Saenphet K. The toxicology of Butea superba Roxb. Southeast Asian Journal of Tropical Medicine and Public Health. 2002;33(Suppl 3):155. PDF
4. Ho CCK, Tan HM. Rise of herbal and traditional medicine in erectile dysfunction management. Current Urology Reports. 2011;12:470-478. Springer
5. RxList. Butea superba: uses, side effects, and more. rxlist.com
6. Malaivijitnond S, Ketsuwan A, Watanabe G, Taya K, Cherdshewasart W. Luteinizing hormone reduction by the male potency herb, Butea superba Roxb. Brazilian Journal of Medical and Biological Research. 2010;43(9):843-852. SciELO

These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent any disease. This article is for information only and is not medical advice.