What is the difference between ARBs and ACE inhibitors?

Both lower blood pressure by acting on the renin-angiotensin system, but at different points. ACE inhibitors block the enzyme that forms angiotensin II, while ARBs block angiotensin II from binding to its AT1 receptor. Because ARBs do not raise bradykinin, they usually do not cause the dry cough seen with ACE inhibitors.

Do ARBs cause the same dry cough as ACE inhibitors?

No, ARBs rarely cause the dry cough, which is why patients who cannot tolerate an ACE inhibitor are often switched to an ARB. ARBs can still cause hyperkalemia and carry the same boxed Fetal Toxicity warning, so those cautions carry over.

PTCB Guide to ARBs

Also called Angiotensin II receptor blockers · suffix -sartan · updated July 15, 2026

Quick answer

Mechanism: ARBs block angiotensin II from binding to the AT1 receptor, which relaxes blood vessels and lowers blood pressure. ACE inhibitors instead block the formation of angiotensin II.
High-yield point: ARBs (the -sartan drugs) treat hypertension and heart failure and usually do not cause the dry cough seen with ACE inhibitors, because they do not raise bradykinin.
Key cautions: ARBs still raise potassium (hyperkalemia) and carry a boxed Fetal Toxicity warning, so they are treated as contraindicated in pregnancy.

What gets tested

Recognizing the -sartan suffix and matching brand to generic (Cozaar is losartan, Diovan is valsartan)
That ARBs block angiotensin II at the AT1 receptor, while ACE inhibitors block its formation
The high-yield ACE-versus-ARB point: ARBs do not typically cause the dry cough
That ARBs carry a boxed Fetal Toxicity warning (treated as contraindicated in pregnancy) and can cause hyperkalemia
Common indications: hypertension, heart failure, and diabetic kidney disease

What is not tested

You are not expected to make prescribing decisions. Choosing which ARB a patient should receive, deciding how quickly to titrate a dose, and reciting the detailed enzyme biochemistry of the renin-angiotensin-aldosterone system all sit outside the technician role, as does comparative clinical trial data. Strengths and durations are not off limits, though: PTCE knowledge area 1.4 covers strengths and dose, dosage forms, routes of administration, special handling and administration instructions, and duration of drug therapy. So you should know that ARBs are oral tablets taken long term, usually once daily (losartan and valsartan may be dosed twice daily), with or without food. What the exam leans on hardest is recognition of the class, brand-to-generic matching, the ACE-inhibitor comparison, common side effects, interactions, and counseling points.

Why arbs matter

Losartan ranks among the top 10 most dispensed medications in the United States, and ARBs appear constantly in the Medications domain alongside ACE inhibitors. Knowing how the two classes differ, especially the cough point, is one of the highest-yield comparisons on the exam.

ARBs at a glance

Generic	Brand	Primary indication
losartan	Cozaar	high blood pressure, diabetic kidney disease
valsartan	Diovan	high blood pressure, heart failure, after heart attack
olmesartan	Benicar	high blood pressure
irbesartan	Avapro	high blood pressure, diabetic kidney disease
candesartan	Atacand	high blood pressure, heart failure
telmisartan	Micardis	high blood pressure, cardiovascular risk reduction (brand Micardis tablets are discontinued in the US; generic telmisartan and Micardis HCT are still available)
azilsartan	Edarbi	high blood pressure
eprosartan	Teveten	high blood pressure (brand Teveten and generic eprosartan are discontinued in the US and are no longer dispensed)

Mechanism of action

ARBs selectively block angiotensin II from binding to the angiotensin II type 1 (AT1) receptor. Angiotensin II normally makes blood vessels constrict and triggers aldosterone release, both of which raise blood pressure. By blocking the receptor, ARBs relax blood vessels, lower aldosterone, and reduce blood pressure. This differs from ACE inhibitors, which block the enzyme that converts angiotensin I into angiotensin II: ARBs block the hormone's action at the receptor rather than its formation. Because ARBs do not raise bradykinin levels, they usually do not cause the dry cough associated with ACE inhibitors. The ARBs you are likely to see on the exam and in the pharmacy are losartan, valsartan, olmesartan, irbesartan, candesartan, telmisartan, and azilsartan. Eprosartan (Teveten) is also FDA-approved but is no longer marketed in the United States.

Common and important side effects

Hyperkalemia (high blood potassium)
Hypotension and dizziness, especially after the first dose
Reduced kidney function, particularly with dehydration or renal artery stenosis
Headache and fatigue
Angioedema and cough are possible but much less common than with ACE inhibitors

Key interactions

Potassium-sparing diuretics, potassium supplements, and potassium-containing salt substitutes raise the risk of hyperkalemia
Lithium levels can rise, increasing the risk of lithium toxicity, so levels are monitored
NSAIDs can blunt the blood-pressure-lowering effect and increase the risk of kidney injury, especially with a diuretic on board
Combining an ARB with an ACE inhibitor or with aliskiren (dual blockade of the renin-angiotensin system) raises the risk of hyperkalemia, hypotension, and kidney problems and is generally avoided. Aliskiren is contraindicated with ARBs in patients with diabetes.

Patient counseling notes

ARBs carry a boxed Fetal Toxicity warning and are stopped as soon as pregnancy is detected: tell the pharmacist right away if you are pregnant or may become pregnant
Report swelling of the face, lips, or tongue, or trouble breathing, which can signal rare angioedema
Avoid potassium supplements and salt substitutes that contain potassium unless the prescriber approves
Rise slowly from sitting or lying down to limit dizziness, especially when starting therapy
ARBs are a common alternative for patients who developed a dry cough on an ACE inhibitor

Practice questions

Then test the whole class in context with the drug class identification quiz and the brand and generic quiz.

1. A prescription is written for Diovan. Which generic drug should the technician expect to dispense?

A. Lisinopril
B. Valsartan ✓
C. Losartan
D. Atenolol

Answer: B. Diovan is the brand name for valsartan, an ARB used for hypertension and heart failure. Losartan is also an ARB but is sold as Cozaar, while lisinopril is an ACE inhibitor and atenolol is a beta blocker.

2. How do ARBs lower blood pressure?

A. They block the enzyme that converts angiotensin I to angiotensin II
B. They block angiotensin II from binding to the AT1 receptor ✓
C. They inhibit HMG-CoA reductase
D. They block beta-1 receptors in the heart

Answer: B. ARBs block angiotensin II at the AT1 receptor, preventing vasoconstriction and aldosterone release. ACE inhibitors act earlier by blocking the enzyme that forms angiotensin II.

3. A patient developed a persistent dry cough while taking the ACE inhibitor lisinopril, so the prescriber switches them to losartan. Why are ARBs less likely to cause this cough?

A. ARBs are taken at night
B. ARBs do not raise bradykinin levels ✓
C. ARBs are not absorbed in the stomach
D. ARBs lower potassium

Answer: B. The ACE-inhibitor cough is linked to a buildup of bradykinin. ARBs act at the receptor and do not raise bradykinin, so they rarely cause the cough, which is why intolerant patients are often switched to an ARB.

4. Which condition is a contraindication to ARB therapy?

A. Pregnancy ✓
B. High cholesterol
C. Seasonal allergies
D. Mild acne

Answer: A. ARBs carry a boxed Fetal Toxicity warning and are treated as contraindicated in pregnancy, the same class safety concern seen with ACE inhibitors. The drug is stopped as soon as pregnancy is detected, and a patient who is or may become pregnant should notify the pharmacy.

5. A patient taking valsartan is also prescribed a potassium-sparing diuretic. Which lab value should be monitored most closely?

A. Blood glucose
B. Potassium ✓
C. White blood cell count
D. Uric acid

Answer: B. ARBs raise potassium, and combining one with a potassium-sparing diuretic or potassium supplement further increases the risk of hyperkalemia, so serum potassium should be monitored.

Cheat sheet

Suffix: -sartan
Class: angiotensin II receptor blockers (ARBs)
Blocks: angiotensin II at the AT1 receptor (ACE inhibitors block its formation)
Uses: hypertension, heart failure, diabetic kidney disease
No dry cough like ACE inhibitors, but they still cause hyperkalemia
Boxed Fetal Toxicity warning: treated as contraindicated in pregnancy
Watch: potassium, lithium, NSAIDs, and avoid combining with an ACE inhibitor or aliskiren

Related drug-class guides

ACE Inhibitors Beta Blockers Statins All drug classes

Official sources

PTCB Quiz Prep is an independent study resource, not affiliated with the Pharmacy Technician Certification Board. This guide is for exam preparation, not medical advice. See our editorial standards. Part of the PTCB Medications domain.