What are the odds of health problems from using only dry toilet paper?
Evidence quality 4.13/5
Eight-dimension review score against the quality rubric . Each dimension scored 1–5.
- D1 Source grounding
- 4/5
- D2 Source authority
- 5/5
- D3 Arithmetic
- 3/5
- D4 Uncertainty
- 4/5
- D5 Scope
- 4/5
- D6 Prose
- 5/5
- D7 Perception honesty
- 4/5
- D8 Caveat completeness
- 4/5
Lifetime probability · lifetime, US adult
1 in 100
1.0% lifetime chance
Most people overestimate this.
range 1 in 500 to 1 in 20
≈ As likely as
Perceived
The bidet-vs-toilet-paper debate has become a fixture of online health discourse, with advocates for water cleansing framing dry wiping as a backward hygiene practice that causes UTIs, hemorrhoids, and perianal irritation. Bidet marketing amplifies the perception that dry toilet paper is actively harmful, and viral posts regularly claim that Americans are the only developed-world population still "smearing" rather than washing.
Rough estimate: ~25-50% chance of developing hemorrhoids or UTIs from using only dry toilet paper
Source: editorial intuition, not polled
Actual
~50% of adults develop hemorrhoids by age 50, regardless of wiping method
US adults
Show derivation
Hemorrhoids affect roughly 50% of Americans by age 50 (Johanson & Sonnenberg 1990, Gastroenterology), with prevalence peaking at ages 45-65. However, a 3-year prospective web survey (Asakura et al. 2018, Epidemiology & Infection) found that cumulative incidence of hemorrhoids was not significantly increased or decreased by habitual bidet use vs non-use. A systematic review (Baig et al. 2022, Evidence- Based Complementary and Alternative Medicine) concluded that current evidence does not identify bidet use as a treatment modality for perianal disease. For UTIs, lifetime incidence in women exceeds 50%, but a 2024 study (Kuriyama et al., Cureus) found that wiping direction was not significantly associated with UTI risk in the overall population after adjusting for age and diabetes -- significance appeared only in the 40-59 subgroup. The marginal health benefit of bidet over dry TP is not demonstrated in prospective trials. We conservatively estimate ~1% incremental lifetime risk attributable to dry TP vs water cleansing, reflecting comfort differences rather than infection causation.
Caveats: The 1% estimate is a rough bound on the marginal health difference between dry T…
The 1% estimate is a rough bound on the marginal health difference between dry TP and bidet use, not a measure of absolute risk from either practice. Hemorrhoid and UTI prevalence is high regardless of cleansing method, and the dominant risk factors (diet, straining, sexual activity, menopause, genetics) overwhelm any plausible effect of wiping material. Bidets may offer comfort benefits for people with existing perianal conditions (fissures, post-surgical wounds), but that is symptom management, not disease prevention. Cultural and environmental dimensions (water usage, wet wipe disposal) are outside the health-risk scope of this entry.
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Roughly half of all Americans develop hemorrhoids by age 50, and lifetime UTI incidence in women exceeds 50%. These are the two conditions most frequently cited in the bidet-vs-toilet-paper debate, and both are so common that any marginal effect of cleansing method is buried under far larger risk factors: diet, straining, genetics, sexual activity, menopause. A 3-year prospective study published in Epidemiology & Infection found that habitual bidet use did not significantly reduce the incidence of hemorrhoids or urogenital infections compared to non-use, and that earlier cross-sectional correlations were likely reverse causation — people with symptoms adopting bidets, not bidets preventing disease.
The wiping-direction argument fares similarly under scrutiny. A 2024 study in Cureus examined whether front-to-back vs back-to-front wiping predicted UTI risk and found no significant association in the overall population after adjusting for age and diabetes. A subgroup signal appeared in women aged 40-59, but this was a secondary analysis that awaits replication. The established risk factors for UTI — sexual intercourse, postmenopausal status, catheterization, diabetes — are orders of magnitude more predictive than what material touches the perineum.
Bidets are not without real benefits. Warm water cleansing reduces irritation for people with existing fissures, post-hemorrhoidectomy wounds, or inflammatory bowel conditions. A systematic review in Evidence-Based Complementary and Alternative Medicine acknowledged comfort advantages while concluding that the evidence does not support bidet use as a treatment or prevention modality for perianal disease. The gap between the online discourse and the clinical literature is wide: dry toilet paper is not a health hazard, and switching to a bidet is a comfort preference, not a medical intervention.
Claim ledger
Every number below is what each source reported, with the verbatim quote we relied on and how we arrived at our figure. Click any link to verify directly.
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[1] Gastroenterology (Johanson & Sonnenberg, 1990) — The prevalence of hemorrhoids and chronic constipation: an epidemiologic study
The prevalence of hemorrhoids and chronic constipation: an epidemiologic study- Statistic
4.4% point prevalence of hemorrhoids in the US general population; approximately 50% of adults develop hemorrhoids by age 50; peak prevalence ages 45-65- Excerpt
“"In both sexes, a peak in prevalence was noted from age 45-65 years, with a subsequent decrease after age 65 years... Hemorrhoidal disease is ranked as the third most common outpatient gastrointestinal diagnosis in the United States." ”
- Source data from
- 1990-06-01
- Accessed
- 2026-04-18 · archived copy
- Calculation
- Johanson & Sonnenberg established the epidemiological baseline for hemorrhoid prevalence in the US. The ~50% by age 50 figure has been widely cited for three decades and reflects the near-universal nature of hemorrhoidal disease -- driven by straining, diet, age, and genetics rather than wiping material. This makes any marginal effect of TP vs bidet hard to detect against a 50% background rate.
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[2] Epidemiology & Infection (Asakura et al., 2018) — Relationship between bidet toilet use and haemorrhoids and urogenital infections: a 3-year follow-up web survey
Relationship between bidet toilet use and haemorrhoids and urogenital infections: a 3-year follow-up web survey- Statistic
Cumulative incidence of hemorrhoids and urogenital infections was not significantly increased by habitual bidet toilet use; earlier positive correlations were likely reverse causation- Excerpt
“"Cumulative incidence of haemorrhoids and urogenital infections was not significantly increased by habitual use of a bidet toilet... Positive correlations between urogenital outcomes and habitual bidet toilet use reported earlier were not causal relationships, but rather might have been reverse causation." ”
- Source data from
- 2018-03-26
- Accessed
- 2026-04-18 · archived copy
- Calculation
- This 3-year prospective study is the strongest longitudinal evidence on bidet vs non-bidet health outcomes. Finding no significant difference in hemorrhoid or urogenital infection incidence between habitual bidet users and non-users directly undermines the claim that dry toilet paper causes these conditions. The study also corrected earlier cross-sectional findings that had confused reverse causation (people with symptoms adopting bidets) with bidet-caused harm.
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[3] Cureus (Kuriyama et al., 2024) — Post-Toilet Wiping Style Is Associated With the Risk of Urinary Tract Infection in Women
Post-Toilet Wiping Style Is Associated With the Risk of Urinary Tract Infection in Women- Statistic
Wiping direction was not significantly associated with UTI risk in the overall population after adjusting for age and diabetes; significance appeared only in the 40-59 age subgroup- Excerpt
“"The impact of post-toilet wiping with the arm from the front between the legs on UTI events, adjusting for the age and history of diabetes mellitus, was not statistically significant both in males and females when analyzed overall." ”
- Source data from
- 2024-05-10
- Accessed
- 2026-04-18 · archived copy
- Calculation
- This study examined wiping direction (front-to-back vs back-to-front) and UTI risk. The overall null finding after adjustment suggests that wiping technique -- whether with dry TP, wet wipes, or bidet -- is a weak predictor of UTI compared to established risk factors (sexual activity, menopause, catheterization, diabetes). The subgroup finding in ages 40-59 was a secondary analysis and awaits replication.