Bacterial, viral, and protozoal infections may occur in the area surround the rectum. These may be the result of a sexually transmitted disease.

An anorectal abscess is an infection that forms a pocket of pus within the tissues around the anus. It is treated surgically by incision and drainage.

It most often occurs in the middle of the night and lasts from seconds to minutes, an indicator for the differential diagnosis of levator ani syndrome, which presents as pain and aching lasting twenty minutes or longer. In a study published in 2007 involving 1809 patients, the attacks occurred in the daytime (33 per cent) as well as at night (33 per cent) and the average number of attacks was 13. Onset can be in childhood; however, in multiple studies the average age of onset was 45. Many studies showed that women are affected more commonly than men. This can be at least partly explained by men's reluctance to seek medical advice concerning such a delicate case as rectal pain.

During an episode, the patient feels spasm-like, sometimes excruciating, pain in the anus, often misinterpreted as a need to defecate. The pain must arise de novo, that is in absence of clear cause. As such, pain associated with penetrative anal intercourse, trauma or rectal foreign body insertion preclude a diagnosis of proctalgia fugax. Simultaneous stimulation of the local autonomic system can cause erection in males. In some people, twinges sometimes occur shortly after orgasm. Because of the high incidence of internal anal sphincter thickening with the disorder, it is thought to be a disorder of the internal anal sphincter or that it is a neuralgia of pudendal nerves. It is recurrent and there is also no known cure. However, some studies show effective use of botulinum toxin, pudendal nerve block, and calcium channel blockers. It is not known to be linked to any disease process and data on the number of people afflicted vary, but prevalence may be as high as 8–18%. It is thought that only 17–20% of sufferers consult a physician, so obtaining accurate data on occurrence presents a challenge.

The pain episode subsides by itself as the spasm disappears on its own, but may reoccur.

High-voltage pulsed galvanic stimulation (HGVS) has been shown to be of prophylactic benefit, to reduce the incidence of attacks. The patient is usually placed in the left lateral decubitus position and a sterile probe is inserted into the anus. The negative electrode is used and the stimulator is set with a pulse frequency of 80 to 120 cycles per second. The voltage (intensity) is started at 0, progressively raised to a threshold of patient discomfort, and then is decreased to a level that the patient finds comfortable. As the patient's tolerance increases, the voltage can be gradually increased to 250 to 350 Volts. Each treatment session usually lasts between 15 and 60 minutes. Several studies have reported short-term success rates that ranged from 65 to 91%.

There is considerable research into the causes, diagnosis and treatments for FGIDs. Diet, microbiome, genetics, neuromuscular function and immunological response all interact. Heightened mast cell activation has been proposed to be a common factor among FGIDs, contributing to visceral hypersensitivity as well as epithelial, neuromuscular, and motility dysfunction.

Functional gastrointestinal disorders are very common. Globally, irritable bowel syndrome and functional dyspepsia alone may affect 16–26% of the population.