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Last reviewed on RxList: 4/13/2009
Slow-K Side Effects Center

Last reviewed on RxList 11/14/2016

Slow-K (potassium chloride) is an electrolyte replenisher, a mineral supplement used to prevent or treat low amounts of potassium in the blood. Slow-K is available in generic form. Common side effects of Slow-K include:

  • stomach pain or upset,
  • nausea,
  • vomiting,
  • gas,
  • diarrhea, and
  • rarely, skin rash.

Tell your doctor if you have serious side effects of Slow-K including:

  • difficult or painful swallowing, or
  • feeling as if the capsule/tablet is stuck in your throat.

Dosage of Slow-K is adjusted for each individual patient. The dose for the prevention of hypokalemia is generally 20 mEq per day. Doses of 40-l00 mEq per day or more are used for the treatment of potassium depletion. Dosage should be divided if more than 20 mEq per day is given, so that no more than 20 mEq is given in a single dose. Slow-K may interact with potassium-sparing diuretics, ACE inhibitors, angiotensin receptor blockers, salt substitutes containing potassium, digoxin, drospirenone, anticholinergic drugs, antihistamines, antispasmodic drugs, anti-Parkinson's drugs, belladonna alkaloids, or bladder control drugs. Tell your doctor all medications you are taking. Slow-K should be used only when prescribed during pregnancy. Potassium passes into breast milk. Consult your doctor before breastfeeding.

Our Slow-K (potassium chloride) Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Slow-K Consumer Information
SIDE EFFECTS: Upset stomach, nausea, vomiting, gas, or diarrhea may occur. If any of these effects persist or worsen, tell your doctor or pharmacist promptly.

An empty tablet or capsule shell may appear in your stool. This effect is harmless because your body has already absorbed the medication.

Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.

Tell your doctor right away if you have any serious side effects, including: difficult/painful swallowing, feeling as if the capsule/tablet is stuck in your throat.

Get medical help right away if you have any very serious side effects, including: vomit that looks like coffee grounds, stomach/abdominal pain, black/tarry stools.

A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.

This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.

In the US -

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

Read the entire patient information overview for Slow-K (Potassium Chloride)

Slow-K Professional Information


One of the most severe adverse effects is hyperkalemia (see CONTRAINDICATIONS, WARNINGS, and OVERDOSAGE). There also have been reports of upper and lower gastrointestinal conditions including obstruction, bleeding, ulceration, and perforation (see CONTRAINDICATIONS and WARNINGS).

The most common adverse reactions to oral potassium salts are nausea, vomiting, flatulence, abdominal pain/discomfort, and diarrhea. These symptoms are due to irritation of the gastrointestinal tract and are best managed by taking the dose with meals or reducing the amount at one time.

Skin rash has been reported rarely.

Read the entire FDA prescribing information for Slow-K (Potassium Chloride)

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© Slow-K Patient Information is supplied by Cerner Multum, Inc. and Slow-K Consumer information is supplied by First Databank, Inc., used under license and subject to their respective copyrights.

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