On clinical examination, doctors note the presence of tenderness upon palpation of the muscle masses in the upper and lower extremities. “Our patient has difficulty sitting, standing, and even walking with two crutches,” note the authors of this case report published on July 17, 2024, in The Journal of Internal Medicine. He added that «Muscle weakness is rated at 3/5 in the quadriceps, 3/5 in the adductors, and 4/5 in the foot flexors. This patient also has difficulty opening a bottle and bringing his hands to his mouth.». However, it does not affect the muscles that support the neck.

The laboratory results show, in particular, a significant decrease in blood potassium levels: hypokalemia at 2.7 mmol/L (defined as a serum potassium concentration below 3.5 mmol/L). There is also hypophosphatemia at 0.67 mmol/L (corresponding to a serum phosphate level below 0.81 mmol/L), an elevated CPK (creatine phosphokinase) level of 820 international units per liter (IU/L), which is far above the normal range for men (38–174 IU/L). This CPK level suggests rhabdomyolysis, that is, the breakdown of skeletal muscle tissue, which clinically manifests as muscle weakness and myalgia.

An infectious cause can be ruled out a priori in this patient, who has no fever and shows no signs of an inflammatory syndrome based on the blood test results. Since heart rhythm disturbances can occur in cases of hypokalemia, the doctors performed an electrocardiogram (ECG) on him. However, in his case, the marked hypokalemia was not accompanied by any ECG abnormalities.

As is often the case, it was the patient’s medical history that led to the diagnosis, providing the doctors with «the solution on a silver platter.».

The Crucial Importance of Interrogation

The patient does indeed admit to consuming more than three liters of Coca-Cola per day for over two years. The overall clinical and laboratory findings therefore suggest chronic Coca-Cola intoxication.

After rehydration, administration of potassium and phosphate supplements, and discontinuation of Coca-Cola, the patient’s clinical condition improved significantly, with recovery in full of his muscle strength 48 hours after admission. In other words, everything returned to normal in terms of muscle function for this patient, who had experienced motor impairment caused by excessive consumption of Coca-Cola.

Frédéric Franconieri and his colleagues, who are internists, emphasize the crucial importance of the medical history and conclude their article by stating that «There's no point in ordering a lot of expensive, radiation-exposing, or invasive follow-up tests when the patient is practically handing us the diagnosis on a silver platter...».

Cases Rarely Reported in the Medical Literature

Cases of severe hypokalemia caused by chronic, excessive consumption of Coca-Cola have rarely been reported in the international medical literature. This form of intoxication is generally associated with rhabdomyolysis and hypokalemia. The case reported by the Polynesian physicians is unusual in that the patient also presented with low serum phosphate levels. No clinical case in the literature mentions the association of hypophosphatemia with carbonated beverage intoxication.

The first case of severe hypokalemia caused by excessive consumption of Coca-Cola was reported in 1994 by a team of Japanese obstetrician-gynecologists in a 21-year-old pregnant woman who was hospitalized for fatigue, discomfort, nausea, loss of appetite, and vomiting. For the past six years, she had been drinking at least three liters of a caffeinated cola per day. She had experienced the same symptoms during her first pregnancy two years earlier.

Between 2001 and 2019, several cases of hypokalemia linked to excessive cola consumption were reported in the literature by British, South Korean, American, Greek, Turkish, and Belgian physicians in patients presenting with muscle and neurological symptoms of varying severity.

Hypokalemia Caused by Excessive Consumption of Coca-Cola Zero®

In 2021, doctors at the Limoges University Hospital and the Centre Hospitalier Ouest Réunion (Saint-Paul) reported a case of symptomatic hypokalemia caused by excessive consumption of Coca-Cola Zero®. The case involved a 54-year-old woman who was brought to the emergency department due to a deterioration in her general condition, with a recent weight loss of 7 % related to malnutrition.

For the past month, this woman has been experiencing generalized weakness accompanied by pain in all four limbs, which has gradually led to an inability to walk and repeated falls. The clinical examination upon admission confirmed the presence of tetraparesis, that is, incomplete paralysis of all four limbs, accompanied by the absence of the Achilles tendon reflex (above the heel) and sensory disturbances.

Blood tests reveal, in particular, severe hypokalemia at 1.26 mmol/L and rhabdomyolysis with a CPK level of 16,000 IU/L. Blood gas analysis reveals an increase in blood pH associated with elevated plasma bicarbonate levels (metabolic alkalosis with a pH of 7.59 and a bicarbonate level of 57.6 mmol/L). Repeated electrocardiograms show abnormal findings.

The patient was then admitted to the intensive care unit and received, among other things, potassium supplementation. Her metabolic abnormalities normalized within 72 hours, with no relapse observed after potassium supplementation was discontinued. At the same time, the patient regained her muscle strength.

It was her medical history that led to the diagnosis. In fact, she has been drinking two to five liters of Coca-Cola Zero® a day for more than ten years. Her symptoms (tetraparesis secondary to hypokalemic alkalosis) are attributable to excessive consumption of this sugar-free, caffeinated soda.

This clinical observation therefore highlights the importance for physicians to be able to recognize severe symptomatic hypokalemic alkalosis caused by excessive consumption of regular or Diet® Coca-Cola, since complications can be serious, but the symptoms are reversible once consumption has ceased and the electrolyte imbalance has been corrected.

«During follow-up, the patient resumed her excessive and compulsive consumption of Coca-Cola Zero® and her serum potassium level rose again to 2.8 mmol/L,», Florence Couillard, Chloé Ayroulet, and their colleagues, who are internists, point out in an article published in the journal Clinical Nutrition and Metabolism.

The mechanisms underlying Coca-induced hypokalemia

As is well known, classic Coca-Cola contains carbonated water, plant extracts, caffeine, additives, and sugar (fructose and glucose). Caffeine can cause severe hypokalemia because it causes potassium to enter the cells. In fact, caffeine works by stimulating the activity of a protein located on the outer cell membrane, whose enzymatic activity uses energy derived from the breakdown of the energy molecule ATP into cyclic AMP (cAMP). More specifically, caffeine causes an increase in intracellular cAMP levels, which stimulates the activity of the sodium-potassium (Na⁺, K⁺-ATPase), which facilitates the influx of potassium into the intracellular space. In addition, caffeine increases renal potassium excretion by stimulating the production of renin, a hormone produced by the kidneys.

As for the fructose ingested in large quantities through excessive consumption of Coca-Cola, the excess cannot be absorbed by the digestive system. As a result, a large amount of fructose remains in the colon, causing osmotic diarrhea, since the non-absorbable soluble solutes remain in the digestive tract and retain water.

Finally, the large amounts of glucose in soda lead to increased insulin production. This hyperinsulinemia also causes potassium to be redistributed into the intracellular space.

Coca-Cola Zero® contains caffeine and sweeteners (aspartame, acesulfame potassium) to replace sugar.

In 2019, Belgian doctors reported in the journal Louvain Medical The case of a 60-year-old female patient admitted to the emergency department with a complete loss of appetite, extreme fatigue, diarrhea, and abdominal cramps. This woman, who is experiencing generalized weakness, is completely unable to walk. She has been bedridden for a week.

Blood tests revealed hypokalemia at 1.44 mmol/L, as well as rhabdomyolysis (CPK 6,561 IU/L). A thorough interview with the patient eventually revealed that she has been drinking about ten liters of cola a day for years.

Five days after completely stopping consumption, the potassium level returned to normal and supplementation was discontinued. A few weeks after his discharge from the hospital, his primary care physician noted a marked improvement in his overall condition and the absence of diarrhea. His serum potassium levels were normal, as were his CPK levels, without any potassium supplementation.

Marc Gozlan (Follow me on X, Facebook, LinkedIn, Mastodon, BlueSky, and on my other blog ‘Diabetes in All Its Forms‘, dedicated to the many facets of diabetes—already 69 posts).

For more information:

Franconieri F, Oehler E, Grémain V. A diagnosis served on a Tahitian platter. Rev Med Interne. July 17, 2024:S0248-8663(24)00628-3. doi: 10.1016/j.revmed.2024.05.021

Couillard F, Ayroulet C, Roussin C, et al. Symptomatic hypokalemia caused by excessive consumption of Coca-Cola Zero®. Nutr. Clin. Metab. Nov. 2021;35(4):317-320. doi: 10.1016/j.nupar.2021.04.003

Henry J, Lagneaux E, Lambert M, et al. A rare cause of hypokalemia. Louvain Med. Oct. 2019: 474–77.

Ak R, Doganay F, Ozdemir S, et al. Excessive consumption of cola-based beverages as a risk factor for hypokalemia and rhabdomyolysis. Marmara Med J. 2016; 29(2):121-23. doi: 10.5472/MMJcr.2902.04

Dubey D, Sawhney A, Sharma A, Dubey D. Paroxysmal paralytic attacks resulting from excessive cola consumption. Clin Med Res. September 2014;12(1-2):61-4. doi: 10.3121/cmr.2013.1167

Sharma R, Guber HA. Cola-Induced Hypokalemia: A Case Report and Review of the Literature. Endocr Pract. Jan–Feb 2013;19(1):e21–3. doi: 10.4158/EP12241.CR

Tsimihodimos V, Kakaidi V, Elisaf M. Cola-Induced Hypokalemia: Pathophysiological Mechanisms and Clinical Implications. Int J Clin Pract. June 2009;63(6):900-2. doi: 10.1111/j.1742-1241.2009.02051.x

Packer CD. Cola-induced hypokalemia: a super-sized problem. Int J Clin Pract. June 2009;63(6):833-5. doi: 10.1111/j.1742-1241.2009.02066.x

Packer CD. Chronic hypokalemia due to excessive cola consumption: a case report. Cases J. July 14, 2008;1(1):32. doi: 10.1186/1757-1626-1-32

Lee HJ, Kim DW, Cho HS, et al. Hypokalemic paralysis caused by excessive cola consumption. Nephrol Dial Transplant. September 2007;22(9):2729. doi: 10.1093/ndt/gfm355

Rice JE, Faunt JD. Excessive cola consumption as a cause of hypokalemic myopathy. Intern Med J. July 2001;31(5):317-8. doi: 10.1046/j.1445-5994.2001.00063.x

Matsunami K, Imai A, Tamaya T. Hypokalemia in a Pregnant Woman with a History of Long-Term, Heavy Cola Consumption. Int J Gynaecol Obstet. Mar 1994;44(3):283-4. doi: 10.1016/0020-7292(94)90182-1