Reviewed on 6/11/2021
Other Name(s):

Atomic number 55, Caesium, Cesio, Césium, Cesium-137, Cesium Chloride, Chlorure de Césium, Cs, CsCl, High pH Therapy, Numéro Atomique 55, Traitement à pH élevé.


Cesium is an element. In its natural state, cesium is not radioactive. However, it can be made radioactive in the laboratory. People use both forms of cesium for medicine.

Despite serious safety concerns, non-radioactive cesium is taken by mouth for treating cancer. This is sometimes called “high pH therapy.” According to people who promote high pH therapy, taking cesium chloride by mouth reduces the acidity of tumor cells (raises their pH), which are described as very acidic. But these claims are not supported by science. There is no scientific research that indicates tumor cells differ in pH from normal cells or that cesium affects the pH of tumor or normal cells.

Non-radioactive cesium is also used to treat depression.

Healthcare providers sometimes treat cancer patients with radioactive cesium (cesium-137).

In industry, radioactive cesium is also used in instruments that measure thickness, moisture, and liquid flow.

How does it work?

There isn't enough information to know how cesium might work. Some people who promote “high pH therapy” say cesium affects the pH (acidity) of cancer cells, but there's no scientific research to support this claim.


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Uses & Effectiveness

Insufficient Evidence to Rate Effectiveness for...

  • Cancer. Early research suggests that cesium in combination with other vitamins and minerals might reduce the death rate in some patients with various types of cancer.
  • Depression.
  • Other conditions.
More evidence is needed to rate the effectiveness of cesium for these uses.

Natural Medicines Comprehensive Database rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, and Insufficient Evidence to Rate (detailed description of each of the ratings).

Side Effects

High doses of cesium might be UNSAFE. There are reports of severe life-threatening low blood pressure and irregular heartbeat in some people who took high doses of cesium for several weeks. There isn't enough information to know if lower doses of cesium are safe. Some people who take cesium by mouth can also have nausea, diarrhea, and loss of appetite. Tingling of the lips, hands, and feet may also occur.


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Special Precautions & Warnings

Pregnancy and breast-feeding: Not enough is known about the use of cesium during pregnancy and breast-feeding. Stay on the safe side and avoid use.

Irregular heartbeat: Cesium might make irregular heartbeat worse. Don't use cesium if you have this condition.


Medications that can cause an irregular heartbeat (QT interval-prolonging drugs)Interaction Rating: Major Do not take this combination.

Cesium might cause an irregular heartbeat. Taking cesium along with medications that can cause an irregular heartbeat might cause serious side effects including heart arrhythmias.

Some medications that can cause an irregular heartbeat include amiodarone (Cordarone), disopyramide (Norpace), dofetilide (Tikosyn), ibutilide (Corvert), procainamide (Pronestyl), quinidine, sotalol (Betapace), thioridazine (Mellaril), and many others.

Medications for inflammation (Corticosteroids)Interaction Rating: Moderate Be cautious with this combination.Talk with your health provider.

Some medications for inflammation can decrease potassium in the body. Cesium might also decrease potassium levels in the body. Taking cesium along with some medications for inflammation might decrease potassium in the body too much.

Some medications for inflammation include dexamethasone (Decadron), hydrocortisone (Cortef), methylprednisolone (Medrol), prednisone (Deltasone), and others.

Water pills (Diuretic drugs)Interaction Rating: Moderate Be cautious with this combination.Talk with your health provider.

Large amounts of cesium can decrease potassium levels in the body. "Water pills" can also decrease potassium in the body. Taking cesium along with "water pills" might decrease potassium in the body too much.

Some "water pills" that can deplete potassium include chlorothiazide (Diuril), chlorthalidone (Thalitone), furosemide (Lasix), hydrochlorothiazide (HCTZ, Hydrodiuril, Microzide), and others.


The appropriate dose of cesium depends on several factors such as the user's age, health, and several other conditions. At this time there is not enough scientific information to determine an appropriate range of doses for cesium. Keep in mind that natural products are not always necessarily safe and dosages can be important. Be sure to follow relevant directions on product labels and consult your pharmacist or physician or other healthcare professional before using.

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You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.

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Cesium chloride and ventricular arrhythmias. Canadian Adverse Reaction Newsletter 2008;18:3-4.

Environmental Protection Agency. Cesium. 2002. Available at: www.epa.gov/radiation/radionuclides/cesium.htm

Lyon AW, Mayhew WJ. Cesium toxicity: A case of self-treatment by alternate therapy gone awry. Ther Drug Monit 2003;25:114-6. View abstract.

Neulieb R. Effect of oral intake of cesium chloride: a single case report. Pharmacol Biochem Behav 1984;21:15-6. View abstract.

O'Brien CE, Harik N, James LP, et al. Cesium-induced QT-interval prolongation in an adolescent. Pharmacotherapy 2008;28:1059-65. View abstract.

Pinsky C, Bose R. Pharmacological and toxicological investigations of cesium. Pharmacol Biochem Behav 1984;21:17-23. View abstract.

Pinter A, Dorian P, Newman D. Cesium-induced torsades de pointes. N Engl J Med 2002;346:383-4. View abstract.

Sartori HE. Cesium therapy in cancer patients. Pharmacol Biochem Behav 1984;21:11-3. View abstract.

Sartori HE. Nutrients and cancer: an introduction to cesium therapy. Pharmacol Biochem Behav 1984;21:7-10. View abstract.

Vyas H, Johnson K, Houlihan R, et al. Acquired long QT syndrome secondary to cesium chloride supplement. J Altern Complement Med 2006;12:1011-4. View abstract.

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