Apple Cider Vinegar for Kidney Stones

Apple cider vinegar has not been shown to prevent or dissolve kidney stones. The only trial of it, a randomised crossover study in 20 healthy adults, gave six of them 30 ml a day, diluted in a litre of water, for one week. Their 24-hour urinary citrate, a natural inhibitor of calcium stones, did not change significantly, and neither did urine pH or volume, but the trial was too small to rule an effect out (Baker 2026).

The more encouraging result comes from China, where 72 people with past calcium oxalate stones drank either 5 ml of mature vinegar three times a day or water for 6-12 months; repeat stones were about two-thirds less likely on vinegar (relative risk 0.31) (Zhu 2019). It was a small pilot of a different vinegar. We rate the evidence insufficient: nothing yet justifies using apple cider vinegar in place of proven prevention.

Citrate in urine binds calcium and inhibits crystallisation (Phillips 2015), and a low urinary citrate is a known risk factor for stones (Pachaly 2016). How much a drink changes urinary pH and citrate depends mainly on its bicarbonate and citrate content; citrate from citrus juice is absorbed and turned into bicarbonate, an alkali load that raises urinary citrate (Siener 2016). Prescribed citrate salts such as potassium citrate work this way and reduced new stone formation in a Cochrane review (risk ratio 0.26) (Phillips 2015).

Apple cider vinegar is different. Its acid is acetic acid, and the daily drink in the US trial contained no alkali citrate, though the trial authors estimated its total alkali load at 21 mEq a day and suggested this could raise citrate through systemic alkalinisation (Baker 2026). A laboratory analysis of products used by stone formers measured far less: 0.6 mEq of alkali per serving of a common apple cider vinegar, against 9.5 mEq for a grapefruit juice and about 20 mEq for two other commercial products tested (Joshi 2021). The estimates disagree, and neither shows an effect on urine.

In rats with chemically induced crystals, vinegar or 5% acetate raised urinary citrate, lowered urinary calcium and reduced kidney crystals. The authors traced this to acetate raising histone acetylation in kidney cells, which switched on microRNAs that turn down a transporter that reabsorbs citrate and a protein that controls calcium loss (Zhu 2019). A second rat study found vinegar reduced crystals and urinary oxalate and raised blood acetate (Liu 2022), although the first had found no change in oxalate (Zhu 2019). In a lab dish, apple cider vinegar dissolved calcium oxalate crystals at 5-30 μg/ml (Singh 2023).

None of this shows that a person drinking apple cider vinegar will form fewer stones. The rats received vinegar by stomach tube at body-weight doses, the dish experiment has no kidney in it, and the one human trial of apple cider vinegar found no significant rise in urinary citrate (Baker 2026).

There is no established dose of apple cider vinegar for kidney stones. The US trial mixed 30 ml of apple cider vinegar with water to a total of 1 litre, sweetened to taste if wanted, and participants drank it over each day for seven days; lemon water was 120 ml of lemon concentrate made up to 1 litre. The trial excluded people with chronic kidney disease, reflux, pregnancy or blood-pressure medicines, so it says nothing about safety in those groups (Baker 2026). The Chinese trial used 5 ml of mature vinegar three times a day, providing 12.5 mEq of acetate, for 6-12 months (Zhu 2019). In the same paper, daily vinegar drinkers took more than 15 ml a day (Zhu 2019).

Always dilute it. A teenager who drank a vinegar beverage daily without enough dilution developed ulcers along the whole oesophagus (Chang 2020), and apple cider vinegar tablets varied widely in acid content and labelling when tested (Hill 2005).

The APUL trial randomised 20 adults without stones to two of four drinks, each taken daily for a week with a two-week washout between. Six completed the apple cider vinegar arm. Their adjusted urinary citrate rose by 125.7 mg/day, but the 95% confidence interval ran from -74.1 to 325 mg/day, and changes in pH (+0.21) and volume (+42.6 ml) were also not significant. Coconut water (+273.8 mg/day) and lemon water (+167.7 mg/day) did raise citrate (Baker 2026). No drink other than water has been clearly shown in a randomised trial to prevent stones (Goldfarb 2023).

The authors call the study exploratory: recruitment stopped well short of its target, it was unblinded, adherence wasn't recorded, and it enrolled healthy volunteers rather than stone formers. A real effect could have been missed, so the result means not shown, rather than shown not to work (Baker 2026).

Researchers in Guangzhou randomised 79 adults with past calcium oxalate stones, all stone-free on CT, to 5 ml of mature vinegar three times a day or plain water. Seven withdrew; of the 72 followed, 50 were followed for more than a year and 22 for 6 months. Repeat stones on ultrasound or CT were less common on vinegar (relative risk 0.31, 95% CI 0.12-0.69, P = .0098). Urinary citrate improved in 72% of the vinegar group against 19% of controls, and urinary calcium fell in 56% against 19% (Zhu 2019).

It is a signal, not proof. The vinegar was a Chinese mature vinegar, not apple cider vinegar. The trial was a small single-centre pilot reported inside a paper that is mostly animal and cell work, the control was plain water so the taste could have revealed the group, and no one has repeated it (Zhu 2019).

The same paper cites survey data from over 9000 people linking daily vinegar intake to a lower risk of stones, and found that 61 daily vinegar drinkers had higher urinary citrate (613 vs 446 mg/day, P = .005) and lower urinary calcium than 61 non-drinkers matched on sex, age, BMI, high blood pressure and diabetes (Zhu 2019). That is an observational comparison, so it can't separate vinegar from other differences in diet and lifestyle.

Belief runs ahead of the evidence. In an online survey of 100 adults with stones, 17% believed apple cider vinegar protects against them (Raz 2026). At a US stone clinic, 18 of 95 patients (18.9%) used it and 83 thought it probably or definitely safe; the authors concluded its risks and benefits for stones are unknown (Kim 2026). Half of 103 patients at another stone clinic used some complementary therapy (Joshi 2021).

Diluted, the amounts studied were well tolerated: no adverse effects were reported with 30 ml a day in a litre of water for a week (Baker 2026), and the Chinese trial reported none in stone formers (Zhu 2019). The risks come from the acid. A teenager who drank a vinegar beverage daily without enough dilution developed corrosive ulcers of the oesophagus (Chang 2020), an oesophageal injury was reported after an apple cider vinegar tablet (Hill 2005), and a 15-year-old who drank a glass of apple cider vinegar daily developed erosive tooth wear (Gambon 2012). In lab tests, vinegars stripped minerals from tooth enamel (Willershausen 2014).

Very large intakes have been linked to low potassium, high renin and osteoporosis in a case report (Lhotta 1998). That matters for stone formers on thiazides, which lowered blood potassium and urinary citrate in a study of people with calcium stones (Nicar 1984). For most people the bigger risk is indirect: using vinegar instead of the fluids, diet changes and medicines that guidelines recommend (Hughes 2020).

In 10 people with type 1 diabetes and gastroparesis, 30 ml of apple cider vinegar with a meal slowed stomach emptying even further, and the authors warned this might be a disadvantage for blood sugar control (Hlebowicz 2007).

Apple cider vinegar has few documented drug interactions. The practical concerns are potassium, because heavy use has been linked to low potassium (Lhotta 1998) and thiazides prescribed for stones also lower it (Nicar 1984), and slowed stomach emptying in people with diabetic gastroparesis who use insulin (Hlebowicz 2007).