Klor-Con M20 is a prescription extended-release tablet containing 20 milliequivalents (mEq) of potassium chloride. It’s used to treat or prevent low potassium levels, a condition called hypokalemia. The “M” in the name refers to the tablet’s wax matrix design, which controls how the potassium is released into your body, and “20” indicates the strength.
Why Potassium Matters
Potassium is the most important positively charged mineral inside your cells, with concentrations roughly 40 times higher inside cells than in your bloodstream. Normal blood potassium runs between 3.5 and 5 mEq per liter, and your body actively maintains that range because potassium is essential for nerve signaling, muscle contraction (including your heart), and kidney function. When levels drop too low, you can experience muscle weakness, cramping, fatigue, irregular heartbeat, and in severe cases, dangerous cardiac rhythm problems.
Potassium levels most commonly drop because of medications like certain diuretics (water pills) used to treat high blood pressure or heart failure. Prolonged vomiting, diarrhea, or heavy sweating can also deplete potassium. Klor-Con M20 is prescribed when dietary changes alone, like eating more bananas, potatoes, or leafy greens, aren’t enough to bring levels back to normal.
How the Extended-Release Design Works
Potassium chloride in concentrated form can irritate or even ulcerate the lining of your digestive tract, particularly if it sits in one spot for too long. Klor-Con M20 uses a wax matrix system to solve this problem. The tablet is film-coated (not enteric-coated) and releases potassium gradually as the wax matrix slowly breaks down in your gut, spreading the dose over time rather than delivering it all at once. This reduces the risk of stomach and intestinal irritation compared to immediate-release potassium supplements.
Because the drug releases slowly, any side effects or toxic reactions can also be delayed by several hours. This is worth knowing: if you feel fine immediately after taking a dose, that doesn’t necessarily rule out a problem developing later.
Typical Dosing
Dosing depends on whether you’re preventing low potassium or treating an active deficiency. For prevention, the typical dose is 20 mEq per day, which is one Klor-Con M20 tablet. For treatment of potassium depletion, doses range from 40 to 100 mEq per day. If your daily dose exceeds 20 mEq, it should be split so that no single dose delivers more than 20 mEq at once. Your prescriber will adjust the amount based on your blood potassium levels, which are monitored with routine lab work.
How to Take It
Swallow the tablet whole with a full glass of water. Do not crush, chew, or suck on it, as that would defeat the extended-release mechanism and dump the full dose into your stomach at once.
If you have trouble swallowing the tablet, two alternatives are available. You can break it in half and take each half separately with water. Or you can dissolve the tablet by placing it in about half a glass of water (4 ounces), waiting roughly two minutes for it to break apart, then stirring for about 30 seconds. Drink the entire suspension right away, using a straw if needed. Then rinse the glass with an additional ounce of water, swirl, and drink. Repeat with one more ounce to make sure you get the full dose.
Side Effects and Risks
The most common side effects are gastrointestinal: nausea, vomiting, stomach discomfort, gas, and diarrhea. These tend to be less severe with the extended-release formulation than with liquid or immediate-release potassium, but they can still occur, especially at higher doses. Taking the tablet with food and a full glass of water helps reduce stomach irritation.
The most serious risk is hyperkalemia, meaning potassium levels that climb too high. Symptoms include tingling in your hands or feet, muscle weakness, a slow or irregular heartbeat, and in extreme cases, cardiac arrest. This risk is higher if you have kidney problems (since the kidneys are responsible for clearing excess potassium), if you take certain blood pressure medications that raise potassium levels, or if you use potassium-sparing diuretics alongside this supplement. Regular blood tests to check potassium levels are a standard part of treatment.
There is also a small risk of gastrointestinal ulceration or narrowing, particularly in people with conditions that slow the movement of food through the digestive tract. If you experience severe stomach pain, bloody or black stools, or difficulty swallowing, those warrant immediate medical attention.
Klor-Con M20 vs. Other Strengths
Klor-Con extended-release tablets come in several strengths: 8 mEq (M8), 10 mEq (M10), 15 mEq (M15), and 20 mEq (M20). The M20 is the highest-strength tablet in the line, which makes it convenient for people who need larger doses because it means fewer pills per day. For someone prescribed 40 mEq daily, that’s two M20 tablets (taken at separate times) rather than four M10 tablets. The active ingredient and release mechanism are the same across all strengths.