Tremors, excessive salivation and difficulty breathing are all signs you may have been bitten by a Brazilian Wandering Spider. In a number of cases, the venom of these arachnids can cause another unexpected symptom; intensely painful erections that last for hours at a time.

Now scientists from around the world are hoping to harvest PnTx2-6, the active ingredient in the spider's venom, to create a natural Viagra that can work in 20 minutes. Brazilian Wandering Spiders can cause priapism - a condition which occurs when blood becomes trapped in the penis, leading to abnormally long-lasting erections.

To discover exactly how PnTx2-6 does this, Gwen Pearson from Wired reported that researchers cut off the penis of a dead mouse, and connected it to an electrical stimulator.

Scientists from the University of Wisconsin were then able to measure the contraction of the muscles in tissue when they came into contact with different chemicals.

They discovered that not only does the venom work, but it also has fewer side effects compared with existing erectile dysfunction drugs, such as Viagra.

Although drugs such as Viagra, Cialis and Levitra have revolutionised treatment in the last ten years, around 30 per cent of men who take them see no improvement.

For these men, the only other options are to inject drugs straight into the penis, or use a pump that manually increases blood supply to the organ. Neither is very popular.

A drug made from spider venom could prove to be an effective alternative.