BMJ Group Medical Reference
This information is for men who have erection problems. It tells you about yohimbine, a treatment used for erection problems. It is based on the best and most up-to-date research.
Does it work?
Probably. Yohimbine may help you get better erections, whatever the cause of your erection problems. In studies, between one-third and two-thirds of men said taking yohimbine helped them have better sex with their partners. But not all studies showed this.
You should talk to your doctor before using this treatment.
What is it?
Yohimbine is a tablet for erection problems, and it can also be taken as a liquid. It's a chemical found in the bark of an African tree. 
Yohimbine isn't widely used in the UK, although your doctor is able to prescribe it if he or she feels it is the right treatment for you. It may also be available on the internet, but you should only take this treatment if prescribed by your doctor.
This is because yohimbine can cause dangerous side effects in some people. Yohimbine can also change how well other medicines work. And other medicines may change how well yohimbine works. Also, supplements of yohimbine available through the internet may be an incorrect dose, or poor quality.
The brand name for yohimbine is Prowess.
How can it help?
Yohimbine can help you get an erection, whatever the cause of your erection problems. Yohimbine can help by: 
Giving you firmer, longer-lasting erections
Making you and your partner more satisfied with sex
Making you more interested in having sex.
But not all studies showed that it worked. One small study found that it did not help men get erections. 
How does it work?
Researchers think that yohimbine works by affecting the nerve cells in the brain that control sex drive. It may help your brain send the signal for you to have an erection. 
Yohimbine fits, like a key in a lock, into certain places on the surface of nerve cells. These places are called alpha-2 receptors. Yohimbine stops other chemicals fitting into these receptors.
Yohimbine tells nerve cells to make more of another chemical called noradrenaline.
Noradrenaline excites cells in your brain that turn 'on' an erection.
The 'on' message goes from your brain, through your nerves, to the blood vessels in your penis.
The blood vessels open wider and extra blood flows into your penis, giving you an erection.
Noradrenaline also tells your brain that you feel like having sex. This also helps you get an erection.