Tripotassium citrate is a potassium salt of citric acid, with the chemical formula C₆H₅K₃O₇ and a molecular weight of 306.39 g/mol. It appears as a white, crystalline powder with no smell and a mildly salty taste. You’ll encounter it in two very different contexts: as a prescription medication for kidney stones and metabolic conditions, and as a common food additive (E332) used to regulate acidity in beverages and processed foods.
Physical and Chemical Properties
Tripotassium citrate dissolves easily in water. One gram dissolves in just 0.65 mL of water, making it highly soluble and well-suited for both liquid medications and food formulations. It dissolves much more slowly in glycerol, requiring about 2.5 mL per gram. The powder is hygroscopic, meaning it readily absorbs moisture from the air, so it needs to be stored in sealed containers. In solution, it acts as a mild alkali, which is the property that makes it medically useful.
How It Works in the Body
Once you ingest tripotassium citrate, the citrate portion is metabolized and converted into bicarbonate, a natural buffer your body uses to neutralize acid. This alkaline load has several downstream effects, particularly in the urinary system.
First, it raises urinary pH, making urine less acidic. This shift alone helps dissolve uric acid crystals, which only form in acidic environments. Second, it increases the amount of citrate excreted in urine. Citrate in urine binds to calcium and forms a soluble complex, which means that calcium is less available to combine with oxalate or phosphate into hard, insoluble stones. Third, citrate directly inhibits the clumping together of calcium phosphate crystals, slowing stone growth even when some crystals do form. The alkali load also tends to reduce the amount of calcium excreted in urine, further lowering the risk of stone formation.
Medical Uses
The primary medical use of tripotassium citrate is preventing kidney stones, particularly calcium oxalate, calcium phosphate, and uric acid stones. It is prescribed for people with hypocitraturia, a condition where urine citrate levels are abnormally low. Low citrate in the urine is one of the most common metabolic risk factors for recurrent kidney stones.
It’s also a preferred treatment for renal tubular acidosis (RTA), a group of conditions where the kidneys fail to properly acidify urine or retain bicarbonate. In RTA, the body becomes too acidic, and potassium levels often drop dangerously low. Tripotassium citrate addresses both problems at once: it supplies alkali to correct the acidosis and delivers potassium to replenish depleted stores. For patients with RTA who also have kidney stones or calcium deposits in the kidneys, potassium citrate is preferred over sodium bicarbonate because the extra sodium in bicarbonate can actually increase calcium in the urine and make stones worse.
Typical Dosage
For adults with mild to moderate hypocitraturia (urinary citrate above 150 mg per day), the standard starting dose is 30 milliequivalents (mEq) per day, split into three doses taken with meals. For severe hypocitraturia (below 150 mg per day), the starting dose is higher at 60 mEq per day, divided into three or four doses throughout the day. Extended-release tablets are taken with meals or within 30 minutes after eating, or with a bedtime snack. Doses above 100 mEq per day have not been studied and are not recommended.
Side Effects and Risks
The most common side effects are gastrointestinal: nausea, stomach discomfort, and occasional vomiting. Extended-release formulations help reduce stomach irritation compared to liquid forms, but some people still experience symptoms. More serious GI signs, like bloody or black stools, severe stomach pain, or vomiting material that looks like coffee grounds, can indicate internal bleeding and need immediate attention.
The most significant medical risk is hyperkalemia, a dangerous rise in blood potassium levels. Symptoms include confusion, numbness or tingling in the hands and feet, muscle weakness (especially in the legs), irregular heartbeat, and difficulty breathing. This risk is highest in people with impaired kidney function, since the kidneys are responsible for clearing excess potassium.
Tripotassium citrate should not be used by people with kidney failure, uncontrolled diabetes, dehydration, active urinary tract infections, peptic ulcers, or intestinal blockages. It also interacts with potassium-sparing diuretics like spironolactone, amiloride, and triamterene, which themselves raise potassium levels. Combining these with potassium citrate can push blood potassium to dangerous levels.
Use as a Food Additive
Outside of medicine, tripotassium citrate is widely used in the food industry under the European designation E332(ii). Its main role is as a buffering agent, helping maintain a stable pH in products that would otherwise become too acidic or change flavor over time. You’ll find it in soft drinks, flavored waters, dairy products, and processed foods where consistent acidity matters for both taste and shelf stability. It also functions as a sequestrant, binding to trace metals in food that could otherwise cause off-flavors or discoloration. At the concentrations used in food, it poses no safety concerns for people with normal kidney function.