High potassium in the blood (hyperkalemia) usually happens because your body cannot get rid of potassium properly, potassium shifts out of cells into the blood, or you’re taking in more than your body can handle, especially if you have kidney problems.

What “high potassium” means

  • Potassium is a mineral that helps your heart, muscles, and nerves work correctly, but too much in the blood can affect the heart’s rhythm and be dangerous.
  • Hyperkalemia is usually found on a blood test; many people feel fine at first, but severe levels can cause weakness, palpitations, or even life‑threatening arrhythmias.

Main medical causes

  • Kidney problems: Acute kidney injury or chronic kidney disease are the most common true causes because damaged kidneys cannot clear excess potassium well.
  • Hormone issues (like low aldosterone or Addison’s disease), uncontrolled diabetes, heart failure, and severe dehydration or sepsis can all reduce potassium excretion or shift potassium into the blood.

Medications and supplements

  • Blood pressure drugs such as ACE inhibitors, ARBs, some beta‑blockers, and potassium‑sparing diuretics can raise potassium, especially in people with kidney disease.
  • Potassium supplements, certain herbal products, and salt substitutes containing potassium (often ~800 mg per ¼ teaspoon) can significantly increase levels.

Diet and “too much potassium”

  • Eating a lot of high‑potassium foods (like dried fruits, bananas, potatoes, tomatoes, spinach, nuts, and avocados) rarely causes high potassium if kidneys are healthy, but it can be important if kidney function is reduced.
  • In people on dialysis or with advanced kidney disease, frequent high‑potassium foods, salt substitutes, or missed dialysis sessions are well‑known triggers for hyperkalemia.

Other triggers and lab mix‑ups

  • Conditions that cause massive cell breakdown (rhabdomyolysis, major burns, crush injuries, severe hemolysis, some blood disorders, or certain tumors) can release large amounts of potassium into the bloodstream.
  • Sometimes the potassium is only “falsely” high (pseudohyperkalemia), for example when the blood sample is badly hemolyzed, drawn through a syringe with a lot of tourniquet time, or in people with very high platelets or white blood cells.

When to worry and what to do

  • High potassium can be an emergency, especially if you have symptoms (chest pain, palpitations, severe weakness, feeling like you might pass out) or have known kidney or heart disease.
  • Anyone with an unexpected high potassium result should contact a clinician promptly to confirm the lab, review medications and diet, and check kidney function rather than trying to “fix it” alone.

TL;DR: What makes your potassium high is most often kidney trouble or medicines that affect potassium, sometimes combined with high‑potassium foods or salt substitutes; less often it’s cell damage or a lab artifact, so every high result needs a proper medical review.

Information gathered from public forums or data available on the internet and portrayed here.