Enalapril belongs to the class of medications called angiotensin converting enzyme (ACE) inhibitors. It is used to treat high blood pressure and congestive heart failure.

This medication works by relaxing blood vessels and by making the heart pump more efficiently. The injectable form is used to lower high blood pressure when the oral form cannot be used.

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are being given this medication, speak to your doctor. Do not stop using this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to use this medication if their doctor has not prescribed it.

The recommended starting dose for high blood pressure is 2.5 mg to 5 mg taken once a day. The usual treatment dose ranges from 10 mg to 40 mg daily, depending on the needs and circumstances of the person using the medication. The dose may need to be adjusted according to how well the kidneys are functioning and the effectiveness of the medication.

The starting dose for children less than 16 years of age is based on body weight and will be calculated by your child's doctor.

The recommended starting dose to treat congestive heart failure is 2.5 mg taken once a day. The dose may be increased gradually to a maximum of 40 mg daily, depending on the effectiveness of the medication.

Many things can affect the dose of medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are using the medication without consulting your doctor.

It is important to use this medication exactly as prescribed by your doctor. If you miss a dose, and it is within 6 hours of your regularly scheduled time, take it as soon as possible and continue with your regular schedule. If more than 6 hours have passed, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store this medication at room temperature, protect it from moisture and keep out of reach of children.

Do not take this medication if you:

• are allergic to enalapril or any ingredients of the medication
• are pregnant or planning to get pregnant
• have been diagnosed with hereditary angioedema
• have had angioedema (a serious allergic reaction which causes the area around the throat and tongue to swell) after taking any other ACE inhibitors (e.g., captopril, enalapril, ramipril)
• have diabetes or kidney disease and are taking aliskiren
• are taking the medication sacubitril

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

• abdominal pain
• confusion
• constipation
• cough (dry, persistent)
• decreased sexual ability
• diarrhea
• fatigue or weakness
• headache
• heartburn
• joint or muscle pain
• loss of appetite
• nausea
• rash or itching
• sore throat
• vomiting

Although most of these side effects listed below don't happen very often, they could lead to serious problems if you do not seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• blurred vision
• breast enlargement (men)
• chest pain
• dizziness, lightheadedness, or fainting (signs of low blood pressure)
• flu-like symptoms (sudden lack of energy, fever, cough, sore throat)
• mouth sores
• shortness of breath
• signs of anemia (low red blood cells; e.g., dizziness, pale skin, unusual tiredness or weakness, shortness of breath)
• signs of bleeding (e.g., unusual nosebleeds, bruising, blood in urine, coughing blood, bleeding gums, cuts that don't stop bleeding)
• signs of infection (symptoms may include fever or chills, severe diarrhea, shortness of breath, prolonged dizziness, headache, stiff neck, weight loss, or listlessness)
• signs of kidney problems (e.g., decreased urination, nausea, vomiting, swelling of legs or hands, fatigue)
• signs of liver problems (e.g., nausea, vomiting, diarrhea, loss of appetite, weight loss, yellowing of the skin or whites of the eyes, dark urine, pale stools)
• signs of too much potassium in the body (e.g., confusion; irregular heartbeat; nervousness; numbness or tingling in the hands, feet, or lips; shortness of breath or difficulty breathing; weakness or heaviness of legs)
• symptoms of low blood sugar (e.g., cold sweat, cool pale skin, headache, fast heart beat, weakness)

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Angioedema: Angioedema (a serious allergic reaction that causes the area around the throat and tongue to swell) may occur with ACE inhibitors, including enalapril, although it is not common. If you experience swelling of the face, tongue, or throat, you should stop taking this medication at once and get immediate medical attention.

People who have had angioedema caused by other substances may be at increased risk of angioedema while receiving an ACE inhibitor such as enalapril.

Blood disorders: In rare cases, a low white blood cell count has been reported by people taking this medication. Your doctor may occasionally monitor your level of white blood cells by performing blood tests. Low white blood cell levels may increase your risk for infection. If you notice any signs of infection (e.g., fever, sore throat), contact your doctor as soon as possible.

Cough: People taking enalapril may develop a dry, persistent cough that usually disappears only after stopping or lowering the enalapril dose. Be sure to tell your doctor of any cough that does not seem to be related to a usual cause.

Diabetes: Enalapril may cause a loss of blood glucose control, and glucose tolerance may change. People with diabetes may find it necessary to monitor their blood sugar more frequently while using this medication. If you have diabetes or are at risk for developing diabetes, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Kidney function: Changes in kidney function have been seen in certain people taking this medication. The use of diuretics (water pills) or aliskiren may further increase the risk of kidney problems for those already at risk for this problem. If you have kidney disease, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Liver function: Changes in liver function have occurred for people with or without preexisting liver problems during treatment with this medication. In most cases, the changes were reversed when the medication was stopped. If you experience symptoms of liver problems such as fatigue, feeling unwell, loss of appetite, nausea, yellowing of the skin or whites of the eyes, dark urine, pale stools, abdominal pain or swelling, and itchy skin, contact your doctor immediately.

Low blood pressure: Occasionally, blood pressure drops too low after taking enalapril. This usually happens after the first or second dose or when the dose is increased. It is more likely to occur for those who take aliskiren, are on dialysis, are experiencing diarrhea or vomiting, are sweating excessively and not drinking enough fluids, have a salt-restricted diet, or are taking water pills. People with these conditions should be monitored closely by their doctor for the first weeks of treatment and whenever the dose of the medication is increased. To reduce the risk of dizziness, get up slowly from a lying down or sitting position. If low blood pressure causes you to faint or feel lightheaded, contact your doctor.

Excessive sweating and lack of fluid intake may lead to an excessive fall in blood pressure because of reduced fluid in your blood vessels. Vomiting or diarrhea may also lead to a fall in blood pressure. Consult your doctor if you feel your blood pressure is too low.

Potassium levels: Increases in blood levels of potassium occur for a small percentage of people taking enalapril. This rarely causes problems, but potassium levels should be monitored by your doctor. Avoid using salt substitutes that contain potassium while you are taking enalapril.

Surgery: It is important that your doctor and anesthesiologist know that you are taking this medication before you undergo any surgical procedures requiring general anesthesia.

Pregnancy: ACE inhibitors such as enalapril may cause severe harm or death to the developing fetus if taken by the mother during pregnancy. This medication should not be used during pregnancy. If you become pregnant while taking this medication, contact your doctor immediately.

Breast-feeding: This medication passes into breast milk in small amounts. If you are a breast-feeding mother and are taking enalapril, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children: The safety and effectiveness of this medication have not been established for infants and children with decreased kidney function.

Seniors: Seniors have an increased risk of experiencing side effects when taking enalapril due to reduced kidney function. Lower doses may be necessary to minimize side effects.

There may be an interaction between enalapril and any of the following:

• acetylsalicylic acid (ASA)
• aldesleukin
• aliskiren
• allopurinol
• alpha-agonists (e.g., clonidine, methyldopa)
• alpha-blockers (e.g., alfuzosin, doxazosin, tamsulosin)
• amiodarone
• amphetamines (e.g., dextroamphetamine, lisdexamfetamine)
• angiotensin II receptor blockers (ARBs; e.g., candesartan, losartan)
• apomorphine
• atypical anti-psychotics (e.g., clozapine, olanzapine, quetiapine, risperidone)
• azathioprine
• barbiturates (e.g., butalbital, pentobarbital phenobarbital)
• beta-adrenergic blockers (e.g., atenolol, propranolol, sotalol)
• brimonidine
• bromocriptine
• calcium channel blockers (e.g., amlodipine, diltiazem, nifedipine, verapamil)
• conivaptan
• dexmethylphenidate
• diabetes medications (e.g., acarbose, canagliflozin, glyburide, insulin, linagliptin, metformin, rosiglitazone)
• diuretics (water pills; e.g., furosemide, hydrochlorothiazide, triamterene)
• drospirenone
• duloxetine
• eplerenone
• everolimus
• "gliptin" diabetes medications (e.g., linagliptin, saxagliptin, sitagliptin)
• grass pollen allergen extract
• guanfacine
• heparin
• iron dextran complex
• iron gluconate
• lanthanum
• levodopa
• lithium
• low-molecular-weight heparins (e.g., dalteparin, enoxaparin, tinzaparin)
• medications that increase potassium levels (e.g., potassium supplements, spironolactone, amiloride, and salt substitutes containing potassium)
• metformin
• methylphenidate
• minoxidil
• morphine
• nabilone
• nitrates (e.g., nitroglycerin, isosorbide dinitrate, isosorbide mononitrate)
• nonsteroidal anti-inflammatory drugs (NSAIDs; e.g., ibuprofen, indomethacin, naproxen)
• obinutuzumab
• other angiotensin-converting-enzyme inhibitors (ACEIs; e.g., captopril,  ramipril)
• pentoxifylline
• phosphodiesterase-5 inhibitors (e.g., sildenafil, tadalafil, vardenafil)
• pregabalin
• quinine
• rasagiline
• riociguat
• ropinirole
• rotigotine
• sacubitril
• selegiline
• sirolimus
• sodium phosphates
• tacrolimus
• temsirolimus
• tizanidine
• tolcapone
• tolvaptan
• trimethoprim
• yohimbine

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.