Many men don't know a whole lot about the workings of their penis. In fact, most guys don't worry much about its general well-being either, which is all a bit surprising, considering how important it tends to be to most of us. But things do go wrong.

Here’s a selection of the various conditions that can affect your penis. It’s not a completely comprehensive list and if you have a specific concern you should consult a medical doctor for proper diagnosis and treatment.

Peyronie’s disease involves the extreme curvature of the penis when erect and is the result of hard, fibrous scar tissue, called plaques, in the shaft of the penis. Peyronie's disease may develop rather quickly or over the course of several months, and can make erections painful and sexual intercourse difficult.

Carcinoma of the penis or penile cancer is quite rare and occurs as a malignant growth on the skin or in the tissue of the penis. It often starts as a small, irregular and painless lump or ulcer on the head or glans of the penis, but usually grows and spreads to the rest of the penis.

Priapism is a serious condition in which the erect penis doesn’t return to its flaccid state. It can be extremely painful, last for hours or even days and, in the worst possible scenario, may require amputation. Gulp!

Erectile dysfunction or impotence is the inability to achieve and maintain an erection that’s firm enough for sexual intercourse. About one in five Australian men over the age of 40 have problems getting or keeping an erection.

Phimosis or paraphimosis involves a situation in which the foreskin is too tight to be pulled over the glans of the penis freely or gets stuck behind its crown.

Lymphangiosclerosis is the hardening of a lymph vessel in the penis that may cause pain during masturbation and sex.

Urinary stones are hard mineral masses that can get lodged anywhere in the urinary tract, including the urethra. These stones can cause a lot of pain.

Diphalia or penile duplication is the exceedingly rare condition of being born with two penises.

Retrograde ejaculation happens when semen enters the bladder rather than emerging from the tip of the penis during orgasm. This leads to a "dry orgasm" and is harmless, but may cause male infertility.

Penile fracture – yes, it can happen! When an erect penis is bent excessively, it can actually break, usually to the accompaniment of a rather sickening popping or cracking sound. Penile fracture results from the rupture of the lining of the corpora cavernosa – the cylindrical structures in the penis that becomes engorged with blood during an erection. It should go without saying that this is a painful situation that requires immediate medical attention.

Pudendal nerve entrapment involves a pinched or compressed nerve in the penis, which can cause considerable chronic pain.

Psoriasis of the penis shows as thick red patches with a well-defined, sharp edge. This can be hereditary, but is rarely a serious condition.

Hypospadias is a birth defect in which the opening of the urethra (called the meatus) at the tip of the penis, through which both urine and semen are expelled from the body, is in the wrong position, at the underside of the glans, instead of the tip.

Different kinds of lumps, spots and rashes can occur on the penis. Although some are signs of sexually transmitted infections (STIs), many are harmless.

Pearly penile papules are small spots (1 to 3 millimetres in diameter) around the circumference of the glans of the penis, which are neither infectious nor in need of treatment.

Fordyce spots are small red or purple spots (1 to 5 millimetres in diameter) on the glans, shaft or scrotum. They’re painless, not itchy and occur singly or in groups of up to 100. Fordyce spots are due to dilated blood vessels and harmless.

Tiny nodules on the scrotum or the base of the penis are likely to be innocuous hair follicles.

Small- to medium-sized raised spots, some containing pus, are probably simple boils or skin spots.

Balantis presents as an irritating, burning, red to orange rash and is an inflammation that affects the head of the penis and/or the foreskin. It may or may not be sexually transmitted.

Syphilis is an STI caused by the bacterium Treponema pallidum. The initial infection typically causes a simple, round and painless ulcer on the penis or scrotum, but with time it spreads to other parts of the body and damages many organs. Syphilis is rare in Australia, but rates are increasing in some communities.

Genital warts are pinkish-white, pinkish-brown or skin-coloured cauliflower-shaped growths and lumps with a moist surface, which are usually found on the top of the penis. They can, however, also occur on the shaft, the scrotum, around the anus and in the mouth and throat. This STI is caused by the human papillomavirus.

Herpes is an STI that presents as small, red bumps that develop into blisters that rupture to form painful open sores and ulcers. The initial episode is often associated with a feverish illness. Infection is common. In fact, 1 in 8 Australians aged 25 years and over have the Herpes simplex virus (type HSV-2) virus.

Male yeast infection. Yeast infections are common among women, but can also occur in men, frequently transmitted sexually. The reddish, itchy and burning rash at the tip of the penis can be treated with over-the-counter antifungal ointment.

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