Hyzaar is primarily used to treat high blood pressure (hypertension) in adults. It’s a fixed-dose combination of losartan and hydrochlorothiazide designed for people who need two medications to reach target blood pressure or who benefit from the complementary effects of an ARB plus a diuretic. By improving blood pressure control, Hyzaar reduces the risk of cardiovascular events such as heart attack, stroke, heart failure exacerbation, and kidney complications. The losartan component has supporting evidence for reducing stroke risk in hypertensive patients with left ventricular hypertrophy, and pairing it with a thiazide can further improve blood pressure and outcomes in appropriate patients.
Clinicians often select Hyzaar when monotherapy (a single medicine) does not adequately control blood pressure, when a patient’s blood pressure is significantly above goal and a two-drug regimen is likely to be needed from the start, or when a diuretic is specifically desirable (for example, in salt-sensitive hypertension). Many patients prefer the convenience of a single tablet over two separate prescriptions. Hyzaar is available in several strengths, offering flexibility to tailor treatment. It is not intended for emergency treatment of very high blood pressure or for initial management of hypertensive crises; instead, it supports long-term, steady control with daily use.
Hyzaar combines two well-studied mechanisms. Losartan, an angiotensin II receptor blocker (ARB), selectively blocks the AT1 receptor, preventing angiotensin II from tightening blood vessels and stimulating aldosterone. This leads to vasodilation, reduced vascular resistance, and modest increases in sodium and water excretion. Unlike ACE inhibitors, ARBs typically do not cause a persistent dry cough and have a lower risk of angioedema, although these reactions can still occur rarely.
Hydrochlorothiazide complements losartan by acting in the distal convoluted tubule of the kidney to reduce sodium reabsorption. This increases urine output, lowers blood volume, and reduces blood pressure. Thiazides can lower potassium levels, whereas ARBs can raise potassium; together, the combination may blunt extremes, but electrolyte shifts can still occur and should be monitored. The result is a balanced approach: losartan reduces vascular tone and the hormonal drive to retain sodium, while hydrochlorothiazide directly enhances salt and water excretion—often making Hyzaar more potent than either agent alone for blood pressure reduction.
Hyzaar is typically taken once daily, with or without food, ideally at the same time each morning to align the diuretic effect with daytime hours. Commonly available strengths include 50/12.5 mg, 100/12.5 mg, and 100/25 mg (losartan/hydrochlorothiazide). A common starting dose for adults is 50/12.5 mg once daily when combination therapy is appropriate from the outset or when adding a diuretic to losartan is clinically indicated. Depending on blood pressure response after several weeks, the dose may be increased to 100/12.5 mg or 100/25 mg once daily. The maximum recommended dose is generally 100/25 mg per day. Dose selection depends on baseline blood pressure, kidney function, other medications, and prior response to therapy.
If you are already on losartan or hydrochlorothiazide separately, your clinician may switch you to the closest equivalent Hyzaar strength for convenience and consistency. Hydration matters: avoid dehydration, especially during hot weather, vomiting, or diarrhea, because volume depletion can trigger low blood pressure, electrolyte imbalances, and kidney stress. Because hydrochlorothiazide may increase urination initially, many people prefer to take Hyzaar in the morning; if nighttime dosing causes sleep disruption due to bathroom trips, ask your clinician whether changing the schedule is reasonable for you.
Regular monitoring is important during dose titration and periodically thereafter. Your care team may check blood pressure at home and in clinic, plus blood tests for electrolytes (sodium, potassium), kidney function (creatinine, eGFR), and occasionally uric acid and glucose. Do not change your dose or stop Hyzaar abruptly without professional guidance. Certain populations—older adults, people with impaired kidney function, or those on multiple antihypertensives—may require a lower starting dose, slower titration, and closer monitoring to reduce the risk of dizziness, fainting, or laboratory abnormalities.
Volume depletion and electrolyte changes are the leading practical concerns. Excessive fluid loss from diuretics, gastrointestinal illness, or inadequate intake can cause low blood pressure (lightheadedness, fainting), acute kidney stress, and changes in sodium or potassium. Because losartan tends to raise potassium while hydrochlorothiazide lowers it, the net effect varies; either high or low potassium can occur. Your clinician may advise periodic labs—especially after dose changes, with intercurrent illness, or if you use other medicines that affect potassium (for example, potassium supplements, salt substitutes, ACE inhibitors, or potassium-sparing diuretics).
Metabolic effects of hydrochlorothiazide warrant attention in some patients. Thiazides can increase uric acid (potentially provoking gout flares), slightly affect blood glucose and lipids, and cause mild photosensitivity. Using sun protection, staying well hydrated, and reviewing your personal risk factors can mitigate issues. People with a history of severe skin reactions to sulfonamide-containing drugs should discuss risks with their clinician, as thiazides are sulfonamide derivatives; true cross-reactivity is uncommon but possible. As with other RAAS-blocking agents, monitor kidney function closely in those with renovascular disease or advanced chronic kidney disease.
Pregnancy and breastfeeding require special caution. Drugs that act on the renin-angiotensin system (including losartan) can harm the fetus, particularly in the second and third trimesters. Hyzaar should be discontinued as soon as pregnancy is detected and replaced with alternatives considered safer during pregnancy. Hydrochlorothiazide may appear in breast milk; discuss risks and benefits of continuing therapy while breastfeeding. Finally, avoid abrupt cessation of antihypertensives without medical advice, since rebound increases in blood pressure can occur.
Hyzaar is contraindicated in patients with known hypersensitivity to losartan, hydrochlorothiazide, or any tablet component, and in individuals with anuria (inability to produce urine). Because losartan acts on the renin-angiotensin system, Hyzaar must not be used during pregnancy due to the risk of fetal injury or death. It should also not be coadministered with aliskiren in patients with diabetes because of increased risks of kidney impairment, hyperkalemia, and hypotension.
Caution is warranted in patients with severe kidney or liver impairment, bilateral renal artery stenosis, a history of angioedema, gout, electrolyte disturbances, or those on medications that significantly affect potassium or kidney function. While not absolute contraindications in many cases, these conditions often necessitate alternative therapies or close monitoring and patient-specific dose adjustments.
Many people tolerate Hyzaar well, but side effects can occur. Commonly reported effects include dizziness or lightheadedness (especially when first starting or increasing the dose), headache, fatigue, and increased urination. As blood pressure normalizes, these symptoms often lessen. Because hydrochlorothiazide can cause photosensitivity, some patients notice increased sunburn risk; using sunscreen and protective clothing helps. Mild gastrointestinal symptoms (nausea, stomach upset) and muscle cramps may appear, often related to fluid and electrolyte shifts.
Laboratory-related effects reflect the pharmacology of both components. Hydrochlorothiazide can lower sodium, potassium, and magnesium; losartan may increase potassium—so the net change in potassium varies. Thiazides can also raise uric acid (gout risk), modestly affect blood sugar and triglycerides, and increase calcium. Rarely, more serious reactions occur: significant hypotension (fainting), kidney function decline, electrolyte abnormalities with symptoms (palpitations, weakness, confusion), severe rash or allergic reaction, pancreatitis, or vision changes (a rare idiosyncratic reaction to thiazides). ARBs rarely cause angioedema (swelling of face, lips, tongue), which is a medical emergency.
Seek urgent care for symptoms of a severe reaction: throat tightness, facial swelling, trouble breathing, chest pain, severe dizziness, confusion, or signs of dangerously high or low potassium (muscle paralysis, heartbeat irregularities). Prompt reporting of new or worsening symptoms to your healthcare team supports safe, effective therapy. In many cases, side effects can be managed by adjusting the dose, timing, or supportive measures (hydration, electrolyte monitoring), or by switching to an alternative regimen if needed.
Hyzaar can interact with several medications and supplements. Agents that raise potassium—such as potassium supplements, salt substitutes containing potassium, potassium-sparing diuretics (spironolactone, eplerenone, amiloride, triamterene), ACE inhibitors, and aliskiren—increase the risk of hyperkalemia, particularly in patients with reduced kidney function. Combining multiple renin-angiotensin system blockers (e.g., ARB plus ACE inhibitor) is generally discouraged due to elevated risks without clear added benefit in hypertension management.
Nonsteroidal anti-inflammatory drugs (NSAIDs), including ibuprofen and naproxen, can blunt the antihypertensive effect, impair kidney function, and increase potassium—especially in older adults or those who are volume depleted. Lithium clearance may be reduced with diuretics and ARBs, potentially causing lithium toxicity; if used together, close monitoring of lithium levels is essential. Cholestyramine and colestipol can reduce hydrochlorothiazide absorption; spacing doses may help. Corticosteroids and amphotericin B can add to potassium loss; digitalis toxicity risk rises when potassium or magnesium are low, underscoring the importance of routine electrolyte monitoring.
Alcohol and other blood pressure–lowering drugs (calcium channel blockers, beta-blockers, alpha-blockers) can have additive effects, increasing the risk of dizziness or orthostatic hypotension. Certain antidiabetic medications may require dose adjustments if thiazides affect blood sugar control. Always provide your clinician with a complete list of prescription drugs, over-the-counter products, and herbal supplements so they can screen for interactions before you start Hyzaar or change your regimen.
If you miss a dose of Hyzaar, take it as soon as you remember the same day. If it’s close to your next scheduled dose, skip the missed dose and resume your regular schedule. Do not take two doses at once to make up for a missed dose. Consider using a daily reminder, pill organizer, or alarm to help maintain consistent dosing, since steady use is key to controlling blood pressure and reducing cardiovascular risk.
Overdose may cause pronounced hypotension (very low blood pressure), dizziness, fainting, dehydration, and electrolyte disturbances that can lead to irregular heart rhythms. Supportive care is the mainstay: seek emergency medical attention, lie down with legs elevated while waiting for help if lightheaded, and do not attempt to self-treat severe symptoms. In a healthcare setting, clinicians may provide IV fluids, monitor electrolytes and kidney function, and treat rhythm abnormalities as needed. Losartan is not significantly removed by hemodialysis, while hydrochlorothiazide may be dialyzable; decisions are individualized by clinical teams.
Store Hyzaar at room temperature (generally 20–25°C or 68–77°F), away from excessive heat, moisture, and direct light. Keep tablets in their original container with the lid tightly closed, and do not store in bathrooms where humidity fluctuates. Always keep medicines out of reach of children and pets. When your prescription expires or is no longer needed, use a local medication take-back program or follow FDA guidance for safe disposal; do not flush unless specifically instructed.
In the United States, Hyzaar (losartan/hydrochlorothiazide) is a prescription-only medication. That means a licensed clinician must evaluate you and determine that Hyzaar is appropriate for your situation before a pharmacy can dispense it. Buying blood pressure medications without a valid prescription or medical oversight is unsafe and not compliant with U.S. regulations. Proper prescribing safeguards are in place to ensure monitoring of blood pressure, electrolytes, kidney function, drug interactions, and pregnancy status, all of which are essential for safe use.
Physician House Calls of Kansas offers a legal and structured solution for people who want convenient access without already having a paper prescription in hand. Through a compliant telehealth visit, a licensed clinician reviews your medical history, current medications, and blood pressure readings. If Hyzaar is appropriate, the clinician issues a valid prescription that is transmitted to a U.S.-licensed pharmacy for dispensing. This telehealth pathway allows you to buy Hyzaar without prescription on hand while maintaining full regulatory compliance and the safety benefits of professional oversight, including lab monitoring and follow-up.
Hyzaar combines losartan (an angiotensin receptor blocker, ARB) with hydrochlorothiazide (a thiazide diuretic) to relax blood vessels and remove excess salt and water, lowering high blood pressure and reducing cardiovascular risk.
It’s prescribed for adults with hypertension, especially when a single medication doesn’t adequately control blood pressure or when both RAAS blockade and a diuretic are desired.
Common strengths are 50/12.5 mg, 100/12.5 mg, and 100/25 mg (losartan/hydrochlorothiazide) taken once daily; many patients start at 50/12.5 mg daily, with a usual max of 100/25 mg daily per prescriber guidance.
Morning is often preferred because the diuretic component can increase urination; consistent timing each day matters most, and some people take it earlier to avoid nighttime bathroom trips.
Partial effects can appear within hours, with full blood-pressure–lowering benefits typically seen in 2–4 weeks; dose adjustments may be made based on readings and tolerance.
Dizziness, lightheadedness, increased urination, fatigue, and electrolyte changes (like low sodium or low potassium) are possible; photosensitivity and mild GI discomfort can also occur.
Severe dizziness/fainting, very low blood pressure, kidney function changes (reduced urine, swelling), severe electrolyte disturbances (muscle cramps, irregular heartbeat), or signs of allergic reaction require prompt care.
Hydrochlorothiazide can lower potassium, while losartan may raise it slightly; the net effect varies, so clinicians often monitor potassium and kidney function, especially after starting or changing dose.
A dry cough is far less common with ARBs like losartan than with ACE inhibitors; if cough occurs, other causes are usually considered first.
ARBs can harm the developing fetus, especially in the second and third trimesters; Hyzaar should not be used during pregnancy, and alternative therapy is preferred in breastfeeding due to HCTZ in breast milk.
It can be used with careful monitoring of kidney function and electrolytes; it is not appropriate in certain conditions like bilateral renal artery stenosis and may need adjustment if kidney function worsens.
NSAIDs can blunt BP control and strain kidneys; lithium levels may rise; potassium supplements or potassium-sparing diuretics increase hyperkalemia risk; alcohol can intensify dizziness; bile acid resins can reduce HCTZ absorption; avoid aliskiren in diabetes.
Thiazides may raise uric acid and provoke gout, but losartan can lower uric acid; the combination may partially offset gout risk, yet susceptible patients should be monitored.
Take it when remembered unless it’s close to the next dose; don’t double up, and resume your regular schedule.
Hyzaar adds hydrochlorothiazide to losartan for a stronger, dual-mechanism BP reduction; Cozaar alone may be preferred initially or when a diuretic isn’t needed or tolerated.
Hyzaar generally lowers blood pressure more than HCTZ alone because losartan provides additional RAAS blockade while HCTZ reduces fluid volume.
Both are effective ARB/HCTZ combinations; individual response, side effects, kidney function, and cost/availability often guide choice rather than a universal “better.”
Telmisartan has a longer half-life and may provide more consistent 24-hour coverage; losartan has uric-acid–lowering properties; both combined with HCTZ effectively reduce BP.
Efficacy is comparable; some patients respond differently to olmesartan versus losartan; olmesartan rarely can cause severe sprue-like enteropathy, which is not associated with losartan.
Both are ARB/HCTZ options; irbesartan and losartan have data in diabetic kidney disease when used without HCTZ, but in combination, selection typically hinges on tolerance, BP targets, and cost.
Side-effect profiles are similar across ARB/HCTZ combos; differences are usually patient-specific rather than drug-specific, with dizziness and electrolyte shifts most common.
Azilsartan plus chlorthalidone can produce robust BP reductions, sometimes greater than HCTZ-based combos, but may carry higher risk of electrolyte abnormalities; monitoring is essential.
A fixed-dose combo like Hyzaar simplifies the regimen and may improve adherence; separate pills allow more flexible titration of each component.
Adding HCTZ to an ARB often mitigates ARB-related potassium increases, but labs are still monitored since net effects vary by patient, diet, and kidney function.
Both combinations lower BP well; ARB-based combos like Hyzaar typically cause less cough and angioedema risk than ACE-based combos, though overall cardiovascular benefits are similar when BP is controlled.
Chlorthalidone has a longer duration and can be more potent than HCTZ, potentially offering stronger 24-hour BP control but with a higher chance of low potassium or low sodium.
Most ARB/HCTZ combinations, including Hyzaar, are available generically; prices vary by pharmacy and insurance, so many clinicians choose based on affordability and patient response.