Butea Superba and Testosterone: The Androgenic Red Kwao Krua

By Ali Kuoppala | Last reviewed Tue 25 September 2018

Medical Review by Gerardo Sison, PharmD

Butea Superba (Red Kwao Krua) is an androgenic herb widely used among the males of Thailand as an aphrodisiac and to improve erectile quality. There’s only a limited amount of studies available to prove its aphrodisiac effects, but what we know about the plant currently, is still quite interesting.

In fact, Butea Superba has a really weird composition. It contains phytoandrogens and also phytoestrogens, however then it also contains anti-estrogenic compounds which could potentially balance out the estrogenicity of the plant.

Here’s more:

Butea Superba as a Testosterone Booster

butea superba for testosteroneThe reason why Thai men use Butea Superba is that they believe that it is a supplement that improves their libido and erectile quality.

However, the scientific evidence for this is lacking.

Even though it works well in test tubes and in rodents (study, study), human studies have failed to replicate the erection improving effects.

NOTE: To be more precise, human studies have not exactly failed to replicate the effects, but they have been so poorly misconducted that the evidence is hard to take seriously (one, for example, claimed the herb to be as effective as Viagra, then, later on, stated that the results were probably false-positive).

But what about the claims of Red Kwao (Butea Superba) being androgenic? Well, there could actually be some truth behind them:

a) Firstly, there’s a rodent study done on male rats where Butea Superba had a dose-dependent testosterone lowering effect. However, as the testosterone levels lowered in serum, the androgenic (masculinizing) effects became more intense (increased spleen weight, increased alkaline phosphatase [ALP], and increased aspartate aminotransferase [AST]). This suggests that the reduction in testosterone could be caused by the increased conversion of testosterone to dihydrotestosterone (DHT) or by increased testosterone utilization by the androgen receptors, both of which would cause testosterone to disappear from the serum, but in return would result in androgenic effects. Similar androgenic results were also seen in female rodents in another study.

b) In this human study which lasted for 3 months, 1,000 mg/day of Butea Superba was able to increase testosterone levels by 11% in men with erectile dysfunction. DHT or any other measurements indicating increased androgenicity were not tested for in the study (unfortunately).

c) One of the active compounds in Butea Superba (3,7,3’Trihydroxy-4′-methoxyflavone) is a strong cAMP phosphodiesterase inhibitor, meaning that it prevents the inactivation of cyclic adenosine monophosphate (cAMP), which is a secondary messenger between cells and hormones. In theory, this should increase testosterone levels (for example forskolin is a herb that increases cAMP, and because of that it also increases testosterone and activates androgen receptors).

d) There is a case study where one 35-years old Thai man was diagnosed with hyperandrogenemia after using an unreported dose of Red Kwao for “a few weeks”. In fact his lab tests showed his DHT levels to be at 1512 pg/mL (reference values are between 250-990 pg/mL) and his principal “side-effect” was, as you can guess, a very high sex drive. After closer inspection by medical experts, the “problematic” source of this increased androgenicity (read: masculinity) was found to be Butea Superba, which the man said he had been taking to prevent hair loss. The man was then told to stop the usage of B. Superba, and one week after cessation of the herb, his DHT levels had returned back to normal and his sexual drive was also back to “normal”.


Butea Superba is a weird herb. There is some evidence that it could cause androgenic effects in the male body, and there is a theoretical explanation to these effects too: phytoandrogens and the possible cAMP boosting effects.

Does it work or not? Honestly, I have no clue, but it’s an interesting herb for sure. I would love to see more studies that would look at its direct effects on DHT.

Ali Kuoppala

Ali Kuoppala is the founder of Anabolic Men. He has authored and co-authored multiple men's health books and focuses on uncovering the methods of optimizing hormonal health. To date, his articles on various websites have been read more than 15-million times. To read more about Ali, visit his Medium article.