When your penis changes color, it doesn't sound great.

But you will be glad to know that in some cases it’s completely normal and there is nothing to worry about.

During sexual arousals, the penis can turn purple or red, it's just because of the extra blood flowing to the penis.

But if things don't go back to normal after the fun, it could be a warning sign.

There are a number of things which could cause the penis to change color so it's important to get it checked out.

Penile cancer

According to the NHS website, a change of color of the penis skin or the foreskin could be a symptom of penile cancer. Men should also look out for a growth or sore that doesn't heal for a month, a foul-smelling discharge, thickening of the skin or foreskin or a rash.

Sexually transmitted diseases

Purple sores can be a symptom of a number of STDs including herpes and syphilis.

There are other symptoms to look out for including a burning sensation, itchiness, fatigue and a fever.

Purpura

A purpura is a purple or red blemish under the skin, which can also be called blood spot.

They're often a sign of an underlying condition such a clotting, nutritional deficits, or inflammation, reports Medical News Today.

Allergic reaction

Unfortunately, your manhood can suffer allergic reactions just like the rest of your body, and it can cause rashes and a change of color.

You might also suffer from Steven-Johnson syndrome, a more serious reaction usually caused by medication, reports the Sun.

If you're suffering from any of the symptoms above it's worth a quick visit to your GP just to check everything is healthy.