Lisinopril
An ACE inhibitor that lowers blood pressure by blocking the conversion of angiotensin I to angiotensin II, reducing vasoconstriction and fluid retention. One of the most prescribed medications in the United States.
How It Works
Lisinopril inhibits angiotensin-converting enzyme (ACE), which normally converts angiotensin I into angiotensin II — a potent vasoconstrictor. By blocking this conversion, lisinopril reduces levels of angiotensin II, causing blood vessels to relax and widen. Aldosterone secretion also decreases, reducing sodium and fluid retention by the kidneys.
In heart failure, reduced afterload and preload improve cardiac output. In diabetic nephropathy, lower intraglomerular pressure from efferent arteriole dilation slows the progression of kidney damage, an effect partly independent of blood pressure control.
Common Uses
- Hypertension (high blood pressure)
- Heart failure (with reduced ejection fraction)
- Post-myocardial infarction (heart attack) — improves survival when started early
- Diabetic nephropathy — slows kidney disease progression in type 1 and type 2 diabetes
Common Side Effects
- Dry, persistent cough — very common (~10–15%); caused by bradykinin accumulation; resolves after discontinuation
- Dizziness, lightheadedness — especially with first doses or volume depletion
- Fatigue, headache
- Hyperkalemia — elevated potassium, especially in those with kidney disease or taking potassium-sparing drugs
- Elevated creatinine (mild, usually transient)
- Angioedema (rare but serious) — sudden swelling of the face, lips, tongue, or throat; requires immediate emergency care
Warnings & Precautions
ANGIOEDEMA: Life-threatening swelling of the tongue, larynx, or throat can occur — even after years of therapy. Seek emergency care immediately for any swelling of the mouth, tongue, or throat. Permanently discontinue lisinopril and do not substitute another ACE inhibitor.
PREGNANCY: ACE inhibitors are contraindicated in pregnancy. Use during the 2nd and 3rd trimesters can cause fetal renal failure and death. Discontinue as soon as pregnancy is detected.
- Avoid concurrent use with ARBs (e.g., losartan) or aliskiren — dual renin-angiotensin system blockade increases hypotension, hyperkalemia, and renal failure risk
- Monitor renal function and potassium — especially in patients with chronic kidney disease or diabetes
- NSAIDs may blunt the antihypertensive effect and worsen renal function
- Caution with potassium supplements or salt substitutes containing potassium chloride
Common Pill Imprints
Lisinopril tablets are typically round. Zestril brand carries "ZESTRIL" imprints; generics vary by manufacturer.
| Imprint | Strength | Manufacturer | Description |
|---|---|---|---|
| ZESTRIL 5 | 5 mg | AstraZeneca (Zestril) | Pink round tablet |
| ZESTRIL 10 | 10 mg | AstraZeneca (Zestril) | Light blue round tablet |
| ZESTRIL 20 | 20 mg | AstraZeneca (Zestril) | Red round tablet |
| LU E12 | 5 mg | Lupin (generic) | Pink round tablet |
Frequently Asked Questions
ACE inhibitors block the breakdown of bradykinin, a peptide that accumulates in the lungs and triggers a persistent dry, tickling cough. It affects about 10–15% of patients and is more common in women and those of Asian descent. If intolerable, an ARB such as losartan is often substituted — it blocks the same blood pressure pathway without affecting bradykinin.
Angioedema is rapid deep-tissue swelling of the face, lips, tongue, or throat. Throat involvement can obstruct the airway and is a medical emergency. It occurs in less than 1% of ACE inhibitor users but can happen even after years of uneventful use. Seek emergency care immediately for any swelling in the mouth or throat — lisinopril must be permanently discontinued.
No. ACE inhibitors are contraindicated in pregnancy. During the second and third trimesters they can cause fetal renal dysplasia, oligohydramnios, limb contractures, and neonatal death. Discontinue as soon as pregnancy is confirmed and contact your provider immediately.
Use caution. Lisinopril lowers aldosterone, reducing urinary potassium excretion. Adding potassium supplements, salt substitutes (potassium chloride), or potassium-sparing diuretics can cause dangerous hyperkalemia. Have potassium levels monitored regularly and discuss any supplements with your provider.