• Hyperkalemia. Because ACE inhibitors often cause an increase in potassium levels in the body, they should not be prescribed for patients who already have abnormally high levels of potassium in their blood (hyperkalemia).

  • Low blood pressure (hypotension). ACE inhibitors may lower blood pressure to dangerous levels in hypotensive patients, especially after the initial dose. However, physicians will often prescribe ACE inhibitors for certain patients with heart failure despite relatively low blood pressure.

  • Kidney disease. In certain types of kidney disease (e.g., bilateral renal artery stenosis), ACE inhibitors can interfere with blood flow to the kidneys and worsen the condition. Also, some forms of kidney disease may cause this medication to be removed from the body at a slower rate, increasing the risk of overdose and/or side effects.

  • Liver disease. Some diseases of the liver can slow the removal of ACE inhibitors from the body. This can lead to an increased risk of side effects and/or overdose.

  • Lupus (systemic lupus erythematosus). Patients with this chronic disorder have an increased risk of blood-related side effects from ACE inhibitors.

  • Previous allergic reaction to an ACE inhibitor.

  • Pregnancy. ACE inhibitors may be harmful to the fetus.