The number of potassium tablets it takes to cause dangerous side effects depends on the tablet strength, which range from 8 milliequivalents to 500 milligrams, and the individual patient, states Drugs.com. Adults with low potassium levels typically take 40 to 100 milliequivalents orally, in equally divided doses daily.
Taking high amounts of potassium is unsafe and can cause confusion, paralysis, low blood pressure, irregular heartbeats and death, according to WebMD. A doctor makes an individual calculation for each patient's potassium supplement needs based on the patient's blood potassium level, which normally should range from 3.5 to 5 milliequivalents per liter. The normal adult requirement and usual dietary intake are between 40 and 80 milliequivalents daily. Amounts up to 90 milliequivalents of dietary and supplemental potassium daily are likely safe. Common potassium supplement side effects include intestinal gas, nausea and vomiting.