Angiotensin-Converting Enzyme Inhibitors (ACE Inhibitors)

Angiotensin-converting enzyme inhibitors (ACE inhibitors) block the conversion of a naturally occurring substance, angiotensin, to a more active form. These medications are widely used to treat hypertension as well as congestive heart failure and other conditions. Drugs in this category include

  • Benazepril hydrochloride (Lotensin, Lotrel) 
  • Captopril  (Capoten)
  • Enalapril maleate (Lexxel, Teczem, Vaseretic, Vasotec)
  • Fosinopril (Monopril)
  • Lisinopril (Prinivil, Prinzide, Zestril, Zestoretic)
  • Moexipril hydrochloride (Uniretic, Univasc)
  • Quinapril hydrochloride (Accupril)
  • Ramipril (Altace)
  • Trandolapril (Mavik, Tarka)
  • and others
Possible Harmful Interaction

Arginine is an amino acid that has been used to improve immunity in hospitalized patients as well as for many other conditions.

Based on experience with intravenous arginine, it is possible that the use of high-dose oral arginine might alter potassium levels in the body, especially in people with severe liver disease.1 This is a potential concern for individuals who take ACE inhibitors.

Possible Harmful Interaction

Licorice root, a member of the pea family, has been used since ancient times as both food and medicine.

Whole licorice ( Glycyrrhiza glabra, or G. uralensis) can cause sodium retention and increase blood pressure, thus counteracting the intended effects of ACE inhibitors.3,4 An often unrecognized source of licorice is chewing tobacco.5

A special form of licorice known as DGL (deglycyrrhizinated licorice) is a deliberately altered form of the herb that should not cause these problems.

Possible Harmful Interaction

ACE inhibitors cause the body to retain more potassium than usual. This could raise your blood levels of potassium too high, a condition called hyperkalemia, which can be dangerous.6-10 Depending on how high your potassium levels are, the symptoms you might experience include irregular heart rhythm, muscle weakness, nausea, vomiting, irritability, and diarrhea. If you are on one of these medications, do not take potassium supplements except on medical advice.

Because ingesting more potassium makes the problem worse, it is important to be aware of the various sources of extra potassium. Besides potassium supplements, sources include high-potassium diets, salt substitutes containing potassium, and potassium-sparing diuretics (diuretics that cause your body to retain potassium).

Your physician will want to keep an eye on the levels of potassium in your blood and let you know if you need to adjust your potassium intake.

Possible Harmful Interaction

St. John's wort (Hypericum perforatum) is primarily used to treat mild to moderate depression.

The herb dong quai (Angelica sinensis) is often recommended for menstrual disorders such as dysmenorrhea, PMS, and irregular menstruation.

ACE inhibitors have been reported to cause increased sensitivity to the sun, amplifying the risk of sunburn or skin rash. Because St. John's wort and dong quai may also cause this problem, taking these herbal supplements during treatment with ACE inhibitors might add to this risk.

It may be a good idea to wear a sunscreen or protective clothing during sun exposure if you take one of these herbs while using an ACE inhibitor.

Possible Benefits and Risks

Individuals taking ACE inhibitors frequently develop a dry cough as a side effect. One study suggests that iron supplementation can alleviate this symptom.13 In this 4-week, double-blind, placebo-controlled trial of 19 individuals, use of iron as ferrous sulfate significantly reduced cough symptoms as compared to placebo.

Keep in mind that it's not healthy to get too much iron. For this reason, we recommend that you seek medical advice before starting iron supplements.

However, remember that iron supplements can interfere with the absorption of captopril and perhaps other ACE inhibitors.2 Iron appears to bind with captopril, resulting in a compound that the body cannot absorb. This, of course, also impairs iron absorption. To minimize any potential problems, take iron supplements and ACE inhibitors 2 to 3 hours apart.

Supplementation Possibly Helpful

ACE inhibitors may cause zinc depletion.11,12 The ACE inhibitors captopril and enalapril attach to the trace mineral zinc. Because zinc in this bound form cannot replace the zinc that the body uses to meet its normal needs, a gradual loss of zinc from body tissues may result. Continued drug therapy could lead to zinc deficiency.

It has been suggested, though not proven, that zinc deficiency might account for some of the side effects seen with ACE inhibitors, such as taste disturbances, poor appetite, and skin numbness or tingling.

Whether zinc supplementation will prevent ACE inhibitor-induced zinc deficiency has not been examined, but it seems reasonable to think that taking extra zinc might help. Generally, zinc supplements should also contain copper to prevent zinc-induced copper deficiency.


1. AHFS Drug Information. Bethesda, MD: American Society of Health-System Pharmacists; 2000:2306-2307.

2. Campbell NR, Hasinoff BB. Iron supplements: a common cause of drug interactions. Br J Clin Pharmacol. 1991;31:251-255.

3. Walker BR, Edwards CR. Licorice-induced hypertension and syndromes of apparent mineralocorticoid excess. Endocrinol Metab Clin North Am. 1994;23:359-377.

4. Wash LK, Bernard JD. Licorice-induced pseudoaldosteronism. Am J Hosp Pharm. 1975;32:73-74.

5. Blachley JD, Knochel JP. Tobacco chewer's hypokalemia: licorice revisited. N Engl J Med. 1980;302:784-785.

6. Good CB, McDermott L, McCloskey B. Diet and serum potassium in patients on ACE inhibitors [letter]. JAMA. 1995;274:538.

7. Warren SE, O'Connor DT. Hyperkalemia resulting from captopril administration. JAMA. 1980;244:2551-2552.

8. Grossman A, Eckland D, Price P, et al. Captopril: reversible renal failure with severe hyperkalaemia [letter]. Lancet. 1980;1:712.

9. Burnakis TG, Mioduch HJ. Combined therapy with captopril and potassium supplementation. A potential for hyperkalemia. Arch Intern Med. 1984;144:2371-2372.

10. Stoltz ML, Andrews CE Jr. Severe hyperkalemia during very-low-calorie diets and angiotensin converting enzyme use. JAMA. 1990;264:2737-2738.

11. Golik A, Modai D, Averbukh Z, et al. Zinc metabolism in patients treated with captopril versus enalapril. Metabolism. 1990;39:665-667.

12. Golik A, Zaidenstein R, Dishi V, et al. Effects of captopril and enalapril on zinc metabolism in hypertensive patients. J Am Coll Nutr. 1998;17:75-80.

13. Lee SC, Park SW, Kim DK, et al. Iron supplementation inhibits cough associated with ACE inhibitors. Hypertension. 2001;38:166-170.

Last reviewed December 2015 by EBSCO CAM Review Board