Toilet-related injuries and deaths
In young boys, one of the most common causes of genital injury is when the toilet seat falls down while they are standing at the toilet. Smaller children run the risk of drowning if they fall headfirst into the toilet bowl. Injuries to adults include bruised buttocks, tail bones, and dislocated hips from unsuspectingly sitting on the toilet bowl rim because the seat is up or loose. Injuries can also be caused by pinching due to splits in plastic seats or by splinters from wooden seats, or if the toilet itself collapses under the weight of the user. Older high tank cast iron cisterns have been known to detach from the wall when the chain is pulled to flush, causing injuries to the user. The 2000 Ig Nobel Prize in Public Health was awarded to three physicians from the Glasgow Western Infirmary for a 1993 case report on wounds sustained to the buttocks due to collapsing toilets. Furthermore, injuries are frequently sustained by people who stand on toilet seats to reach a height, and slip. There are also instances of people slipping on a wet bathroom floor or from a bath and concussing themselves on the fixture. In 2012, 2.3 million toilets in the United States, and about 9,400 in Canada, were recalled due to faulty pressure-assist flush mechanisms which put users at risk of the fixture exploding.
Injuries caused by animals
There are also injuries caused by animals. Some black widow spiders like to spin their web below the toilet seat because insects abound in and around it. Therefore, several persons have been bitten while using a toilet, particularly an outhouse toilet. Although there is immediate pain at the bite site, these bites are rarely fatal. The danger of spiders living beneath toilet seats is the subject of Slim Newton's comic 1972 country song The Redback on the Toilet Seat.
Drop in blood pressure and dangerous Valsalva maneuvers
Some instances of toilet-related deaths are attributed to the drop in blood pressure due to the parasympathetic nervous system during bowel movements. This effect may be magnified by existing circulatory issues. It is further possible that people succumb on the toilet to chronic constipation, because the Valsalva maneuver is often dangerously used to aid in the expulsion of feces from the rectum during a bowel movement. According to Sharon Mantik Lewis, Margaret McLean Heitkemper and Shannon Ruff Dirksen, the “Valsalva maneuver … occurs during straining to pass a hardened stool”. “If defecation is suppressed over long periods, problems can occur, such as constipation or stool impaction. Defecation can be facilitated by the Valsalva maneuver. This maneuver involves contraction of the chest muscles on a closed glottis with simultaneous contraction of the abdominal muscles.” This means that people can die while "straining at stool." In chapter 8 of their Abdominal Emergencies, David Cline and Latha Stead wrote that "autopsy studies continue to reveal missed bowel obstruction as an unexpected cause of death".
A 2001 Sopranos episode "He is Risen" shows a fictional depiction of the risk, when the character Gigi Cestone has a heart attack on the toilet of his social club while straining to defecate.
In the Victorian era, there was a perceived risk of toilets exploding. These scenarios typically include a flammable substance either accidentally or deliberately being introduced into the toilet water, and a lit match or cigarette igniting and exploding the toilet.  In 2014, Sloan's Flushmate pressure-assisted flushing system which uses compressed air to force waste down the drain was recalled after the company received reports of the air tank failing under pressure and shattering the porcelain.
The Who's Keith Moon acquired a reputation for detonating toilets on tour, initially with cherry bombs before turning to more powerful explosives such as M-80s and dynamite. The band's John Entwistle later admitted taking part in the incidents, adding "a lot of times when Keith was blowing up toilets I was standing behind him with the matches."
George II of Great Britain died on the toilet on October 25, 1760 from an aortic dissection. According to Horace Walpole's memoirs, King George "rose as usual at six, and drank his chocolate; for all his actions were invariably methodic. A quarter after seven he went into a little closet. His German valet de chambre in waiting heard a noise, and running in, found the King dead on the floor." In falling he had cut his face.
- Edmund II of England died of natural causes on November 30, 1016, though some report that he was stabbed in the bowels while attending the outhouse. Similarly, Uesugi Kenshin, a warlord in Japan, died on April 19, 1578, with some reports stating that he was assassinated on the toilet.
- Lenny Bruce died of a heroin overdose on August 3, 1966 while sitting on the toilet, with his arm tied off.
- Air Canada Flight 797 was destroyed on June 2, 1983 with 23 fatalities after an in-flight fire began in or around the rear lavatory. Investigators could not determine the cause or exact point of origin for the fire.
- Elvis Presley was found dead on his bathroom floor on August 16, 1977. According to the medical investigator, Presley had "stumbled or crawled several feet before he died"; he had been using the toilet at the time. Elvis biographer Peter Guralnick writes, "It was certainly possible that he had died while 'straining at stool.' " Elvis' personal physician, Dr. George Nicopolous, wrote in his 2009 book, The King and Dr. Nick that "We believe Elvis died from a normal physiological event brought into play called 'Valsalva Maneuver.' This ... caused the heart to stop when the body strained. When Elvis compressed his abdominal aorta by straining, his heart, in response, went into arrhythmia and quit working suddenly." According to Guralnick, "the large intestine was clogged with fecal matter, indicating a painful and longstanding bowel condition. The bowel condition alone would have strongly suggested ... that drug use was heavily implicated in this unanticipated death ..."
- Michael Anderson Godwin, a convicted murderer in South Carolina who had his sentence reduced from death by the electric chair, sat on the metal toilet in his cell while fixing his television. When he bit one of the wires, the resultant electric shock killed him. Another convicted murderer, Laurence Baker in Pittsburgh, was electrocuted while listening to the television on home-made earphones while sitting on a metal toilet.
- A collision between a disabled Cessna 182 and a row of portable toilets on May 2, 2009 at Thun Field (south-east of Tacoma), despite an engine failure at 150 feet (46 m) altitude, ended without fatalities; the toilets "kind of cushioned things" for the 67-year-old pilot.
- British businessman and Conservative politician Christopher Shale was found dead in a portable toilet at the Glastonbury Festival on June 26, 2011. It is suspected he died of a heart attack.
- Aboard ship the head and fittings associated with the head are cited as one of the most common reason for the sinking of tens of thousands of boats of all types and sizes. Heads typically have through-hull fittings located below the water line to draw flush water and eliminate waste. Boats are sunk when fittings fail or the toilet back siphons.
Urban legends have been reported regarding the dangers of using a toilet in a variety of situations. Several of them have been shown to be questionable. These include some cases of the presence of venomous spiders (Except for the Australian redback spider who has a reputation for hiding under toilet seats). In large cities like New York City, sewer rats often have mythical status regarding size and ferocity, resulting in tales involving the rodents crawling up sewer pipes to attack an unwitting occupant. Of late, stories about terrorists booby trapping the seat to castrate their targets have begun appearing. Another myth is the risk of being sucked into an aircraft lavatory as a result of vacuum pressure during a flight.
- "Genital injury". MedlinePlus Medical Encyclopedia. Retrieved 2005-12-20.
- Wyatt JP, McNaughton GW, Tullett WM (December 1993). "The collapse of toilets in Glasgow". Scottish Medical Journal 38 (6): 185. PMID 8146638.
- "Consumer Product Safety Commission News Release: Flushmate Recalls Flushmate® III Pressure-Assisted Flushing System Due to Impact and Laceration Hazards". June 21, 2012.
- See, for instance, Raymond W. Thorp and Weldon Dwight Woodson, Black Widow: America's Most Poisonous Spider (The University of North Carolina Press, 1945), p.65, 156, 188. "Yikes! Black widow spider bites man right were it hurts." Weekly World News, November 7, 1989. James A. Wilkerson, "Black Widow Spider Bites." In Medicine for Mountaineering & Other Wilderness Activities (2001), p.298.
- See Woman on toilet attacked by rat; Rogue rats savage woman on toilet.
- See Sharon Mantik Lewis, Margaret McLean Heitkemper, Shannon Ruff Dirksen, eds., Medical-Surgical Nursing: Assessment and Management of Clinical Problems, 6th edition, Volume 2 (2004), p.951.
- David Cline and Latha Stead, Abdominal Emergencies (2007), p.56-65
- "10 dangerous things in Victorian/Edwardian homes". BBC News. 16 December 2013.
- "Exploding toilets spark recall of flushing system". CBS News. 24 January 2014. Retrieved 27 August 2014.
- Osley, Richard (12 March 2009). "Who's vexed? Rival 'blue plaque' for Moon puts heritage row centre stage". Camden New Journal. Retrieved 28 August 2013.
- Boucher, Geoff (28 June 2002). "John Entwistle, 57; Innovative Bass Player Co-Founded The Who". Los Angeles Times. Retrieved 7 May 2010.
- Tony Long (April 14, 2011). "April 14, 1945: Tweaky Toilet Costs Skipper His Sub". Wired.
- Charles Edmund Maurice, The Story of Bohemia from the Earliest Times to the Fall of National Independence in 1620 (1896), p.117
- Horace Walpole, Memoires of the Last Ten Years of the Reign of George the Second (1822), vol. 2, p. 454.
- Jack Seward, Strange But True Stories from Japan (1999), p.231.
- Jonathan Goldstein, Lenny Bruce is Dead (2001).
- National Transportation Safety Board, Aircraft Accident Report: Air Canada Flight 797 (pdf) p. 59.
- Peter Guralnick, Careless Love: The Unmaking of Elvis Presley (1999), p.651-652.
- Shepherd, Chuck. News of the Weird, Miami New Times. 23 January 1997. Accessed 25 September 2011.
- "US plane crash lands on toilets", BBC News, 2 May 2009
- Senior Tory Christopher Shale found dead at Glastonbury festival, The Guardian, Sunday 26 June 2011
- Pascoe, David, How to keep your boat from sinking
- Boat Owners Association of The United States, Why sailboats sink, 2007
- Mikkelson, Barbara & David P. "Toilet Spiders" at Snopes.com: Urban Legends Reference Pages.
- Mikkelson, Barbara & David P. "The Salami Slicer" at Snopes.com: Urban Legends Reference Pages.
- Mikkelson, Barbara & David P. "Stuck on You" at Snopes.com: Urban Legends Reference Pages.