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Medical Disclaimer: This information is for educational purposes only and is not a substitute for professional medical advice.
Brand Name
Cardura
Generic Name
Doxazosin
Active Ingredient
DoxazosinCategory
Other
Salt Form
Mesylate
Variants
8
This page is for informational purposes only and does not replace medical advice. Before using any prescription or over-the-counter medication for Cardura, you must consult a qualified healthcare professional.
| 2 mg/1 | TABLET | ORAL | 58151-075 |
| 1 mg/1 | TABLET | ORAL | 58151-074 |
| 4 mg/1 | TABLET | ORAL | 58151-076 |
| 8 mg/1 | TABLET | ORAL | 0049-2716 |
| 8 mg/1 | TABLET | ORAL | 58151-077 |
Detailed information about Cardura
Doxazosin is a potent alpha-1 adrenergic receptor blocker used primarily to treat hypertension and the symptoms of benign prostatic hyperplasia (BPH). It works by relaxing smooth muscles in the blood vessels and the prostate gland.
Dosing of Doxazosin must be individualized and carefully titrated to achieve the desired clinical effect while minimizing the risk of hypotension (low blood pressure).
Doxazosin is not currently FDA-approved for use in pediatric patients. The safety and effectiveness of this medication in children have not been established. Healthcare providers generally avoid prescribing this medication to individuals under the age of 18 unless specifically indicated for rare conditions under expert supervision.
Because Doxazosin is primarily metabolized by the liver and excreted in the feces, no dosage adjustment is typically required for patients with renal impairment (kidney disease). However, since these patients may be more sensitive to blood pressure changes, clinicians often monitor them closely during the titration phase.
As Doxazosin is extensively metabolized by the liver, it should be administered with caution to patients with evidence of hepatic impairment. There is limited clinical data regarding the use of Doxazosin in patients with severe liver disease; therefore, healthcare providers may choose to titrate the dose more slowly or use alternative therapies.
Older adults may be more susceptible to the orthostatic effects (dizziness upon standing) of Doxazosin. While the standard starting dose of 1 mg is usually appropriate, subsequent increases should be performed with extra caution. Ensuring the patient is hydrated and understands the risk of falls is paramount.
If you miss a dose of Doxazosin, take it as soon as you remember. If it is almost time for 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 one. If you miss several days of Doxazosin, contact your doctor before restarting, as you may need to start again at the lowest dose (1 mg) to avoid a sudden drop in blood pressure.
An overdose of Doxazosin can lead to severe hypotension (critically low blood pressure). Signs of overdose include extreme dizziness, fainting, blurred vision, and rapid or irregular heartbeat.
Emergency Measures: If an overdose is suspected, the patient should be placed in a supine position (lying on their back) with legs elevated to support blood flow to the brain. Seek emergency medical attention immediately. In a hospital setting, intravenous fluids and vasopressors may be administered to restore blood pressure.
> Important: Follow your healthcare provider's dosing instructions exactly. Do not adjust your dose or stop taking the medication without medical guidance.
Many patients taking Doxazosin experience mild to moderate side effects, particularly when first starting the medication or when the dose is increased. These often include:
Doxazosin is a powerful medication that affects the cardiovascular and urological systems. The most critical safety concern is the risk of a sudden drop in blood pressure, especially when starting the drug or increasing the dose. This can lead to fainting (syncope) and subsequent falls or injuries. Patients should be advised to avoid situations where injury could result should syncope occur during the initiation of Doxazosin therapy.
As of 2026, there are no FDA black box warnings for Doxazosin. However, the potential for severe orthostatic hypotension is a major clinical concern that requires careful monitoring.
While there are few absolute contraindications for drug combinations, certain drugs should be avoided due to the high risk of severe adverse effects:
There are specific circumstances where Doxazosin must never be used because the risks far outweigh any potential benefits:
In these cases, a healthcare provider will perform a careful risk-benefit analysis before prescribing Doxazosin:
Pregnancy Category C (Prior FDA System): There are no adequate and well-controlled studies of Doxazosin in pregnant women. Animal studies have shown some developmental toxicity at very high doses. Doxazosin should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. It is generally not the first choice for treating hypertension in pregnancy, where medications like Labetalol or Methyldopa are preferred.
It is not known whether Doxazosin is excreted in human milk. However, animal studies indicate that Doxazosin can accumulate in rat milk. Because many drugs are excreted in human milk and because of the potential for serious adverse reactions in nursing infants (such as hypotension), a decision should be made whether to discontinue nursing or discontinue the drug, taking into account the importance of the drug to the mother.
The safety and effectiveness of Doxazosin in children have not been established. It is not recommended for use in the pediatric population. Clinical trials for hypertension and BPH have focused exclusively on adult populations.
Doxazosin is a selective, competitive inhibitor of the alpha-1 subtype of adrenergic receptors. In the peripheral vasculature, it inhibits the binding of norepinephrine to alpha-1 receptors on smooth muscle cells. This results in vasodilation and a reduction in total peripheral resistance. In the urogenital tract, Doxazosin specifically targets alpha-1A receptors in the prostate stroma and bladder neck. By relaxing these muscles, it decreases the pressure on the urethra and improves the symptoms of BPH.
The blood-pressure-lowering effect of Doxazosin is gradual, with the maximum effect occurring 2 to 6 hours after dosing. The effect lasts for at least 24 hours, allowing for once-daily administration. Doxazosin has been shown to have a modest beneficial effect on plasma lipids, slightly increasing the HDL (good cholesterol) to total cholesterol ratio and reducing triglycerides. It does not typically affect glucose metabolism, making it a safe option for patients with diabetes.
| Parameter | Value |
|---|---|
Common questions about Cardura
Doxazosin is primarily prescribed for two conditions: high blood pressure (hypertension) and benign prostatic hyperplasia (BPH). For hypertension, it works by relaxing blood vessels so blood can flow more easily, which helps prevent strokes and heart attacks. For BPH, it relaxes the muscles in the prostate and bladder neck, making it easier for men with an enlarged prostate to urinate. It is often used when a patient has both conditions simultaneously. Your doctor will determine the appropriate use based on your specific medical history and symptoms.
The most common side effects reported by patients taking Doxazosin include dizziness, headache, and a general feeling of tiredness or fatigue. Many people also experience swelling in the ankles or feet (edema) and a runny or stuffy nose. These side effects are most likely to occur when you first start the medication or when your doctor increases your dose. Most of these symptoms are mild and tend to go away as your body adjusts to the medicine. However, you should always report persistent or bothersome side effects to your healthcare provider.
It is generally recommended to limit or avoid alcohol while taking Doxazosin. Alcohol can cause your blood vessels to widen, which adds to the blood-pressure-lowering effect of the medication. This combination significantly increases the risk of severe dizziness, lightheadedness, and fainting, especially when standing up quickly. Drinking alcohol can also worsen the drowsiness or fatigue associated with Doxazosin. If you choose to drink, do so very moderately and be aware of how your body reacts. Consult your doctor for personalized advice regarding alcohol consumption.
Doxazosin is generally not recommended during pregnancy unless the potential benefits clearly outweigh the risks to the fetus. It is classified as a medication where human data is limited, and animal studies have shown some potential for harm at very high doses. There are other antihypertensive medications that have a more established safety record for use during pregnancy. If you are pregnant or planning to become pregnant, it is vital to discuss alternative treatments with your doctor. Never stop or start blood pressure medication during pregnancy without professional medical guidance.
For blood pressure, Doxazosin begins to work within a few hours of the first dose, but it may take several weeks of consistent use to see the full antihypertensive effect. For symptoms of an enlarged prostate (BPH), some patients notice an improvement in urine flow within 1 to 2 weeks. However, the maximum benefit for BPH symptoms often takes 4 or even up to 6 weeks to be fully realized. Because the dose must be increased slowly, patience is required during the titration phase. Always continue taking the medication even if you do not feel an immediate change.
You should not stop taking Doxazosin suddenly without consulting your healthcare provider. If you are taking it for high blood pressure, stopping abruptly can cause your blood pressure to rise quickly, which may be dangerous. If you stop taking it for several days and then restart, you may experience a severe 'first-dose' effect with fainting or extreme dizziness. Usually, if the medication needs to be discontinued, your doctor will provide a schedule to taper the dose. If you must restart after a break, your doctor will likely have you start again at the lowest 1 mg dose.
If you miss a dose of Doxazosin, take it as soon as you remember that day. However, if it is almost time for your next scheduled dose, you should skip the missed dose and simply take your next dose at the regular time. Do not take two doses at once to make up for the one you missed, as this increases the risk of dangerously low blood pressure. If you miss your doses for several days in a row, call your doctor before restarting. You may need to start back at a lower dose to avoid side effects.
Weight gain is a possible but relatively uncommon side effect of Doxazosin. When weight gain does occur, it is often related to fluid retention (edema) rather than an increase in body fat. Patients may notice swelling in their legs, ankles, or hands. In clinical trials, only a small percentage of patients reported significant weight changes. If you notice a sudden or large increase in weight while taking this medication, you should contact your doctor. They can determine if the weight gain is due to fluid retention and if a change in treatment is necessary.
Doxazosin can interact with several other medications, so it is important to provide your doctor with a full list of what you are taking. It is often used safely with other blood pressure drugs, but the combination requires careful monitoring. A significant interaction occurs with PDE5 inhibitors used for erectile dysfunction, like Sildenafil (Viagra), which can cause a dangerous drop in blood pressure when combined with Doxazosin. Some antibiotics and antifungal medications can also increase the levels of Doxazosin in your blood. Always check with a pharmacist or doctor before starting any new over-the-counter or prescription drugs.
Yes, Doxazosin is widely available as a generic medication in its immediate-release tablet form. Generic versions are typically much less expensive than the brand-name version, Cardura, while providing the same clinical benefits and safety profile. The extended-release version (Cardura XL) may also be available as a generic in some regions, though it is sometimes more difficult to find than the standard tablets. Most insurance plans cover the generic version of Doxazosin. Ask your pharmacist if a generic equivalent is available for your specific prescription to help manage costs.
Other drugs with the same active ingredient (Doxazosin)
> Warning: Stop taking Doxazosin and call your doctor immediately if you experience any of the following serious symptoms:
With prolonged use, most patients tolerate Doxazosin well. However, some may experience chronic fluid retention (edema), which may require the addition of a diuretic. There is also a risk of developing tolerance to the antihypertensive effects over several years, necessitating a dose adjustment or the addition of another medication. Weight gain has been reported in a small percentage of patients, likely linked to fluid retention rather than fat accumulation.
No FDA black box warnings currently exist for Doxazosin. However, the FDA does require a strong precaution regarding the risk of syncope and "first-dose" hypotension, which is often highlighted in the "Warnings and Precautions" section of the prescribing information.
Report any unusual symptoms or side effects to your healthcare provider. You may also report side effects to the FDA at 1-800-FDA-1088.
Patients taking Doxazosin should undergo regular monitoring to ensure the medication is safe and effective:
Doxazosin can cause significant drowsiness, dizziness, or blurred vision. Patients should not drive, operate heavy machinery, or engage in hazardous activities until they know how the medication affects them, particularly during the first 24 hours of starting the drug or after a dose increase.
Alcohol consumption should be limited while taking Doxazosin. Alcohol acts as a vasodilator and can significantly enhance the blood-pressure-lowering effects of Doxazosin, increasing the risk of severe dizziness, fainting, and falls.
Doxazosin should not be stopped abruptly, especially if being used for hypertension, as this can lead to a rapid increase in blood pressure. If the medication must be stopped, it is usually tapered under medical supervision. If therapy is interrupted for several days, it must be restarted at the 1 mg dose to prevent severe hypotension.
> Important: Discuss all your medical conditions, including any history of low blood pressure or liver disease, with your healthcare provider before starting Doxazosin.
Doxazosin is not known to significantly interfere with common laboratory tests, including PSA (Prostate-Specific Antigen) levels, which is important for the ongoing monitoring of prostate health.
> Important: Tell your doctor about ALL medications, supplements, and herbal products you are taking. A complete list helps prevent dangerous interactions.
Patients who have had an allergic reaction to other alpha-1 blockers in the quinazoline class (Prazosin, Terazosin) are highly likely to be allergic to Doxazosin. This cross-sensitivity is due to the similar chemical structure of these medications. Always inform your doctor if you have ever had a reaction to a blood pressure or prostate medication in the past.
> Important: Your healthcare provider will evaluate your complete medical history, including any history of fainting or liver problems, before prescribing Doxazosin.
Clinical studies of Doxazosin did not identify overall differences in safety or effectiveness between elderly and younger subjects. However, older adults are generally more sensitive to the effects of alpha-blockers. There is a higher risk of orthostatic hypotension and falls in the geriatric population. Healthcare providers often start with the lowest possible dose and monitor blood pressure closely. Polypharmacy (taking multiple medications) is also a concern in the elderly, as it increases the risk of drug-drug interactions.
Pharmacokinetic studies have shown that the disposition of Doxazosin is not significantly altered in patients with renal insufficiency. Therefore, the standard dosing regimen can typically be followed. Doxazosin is not dialyzable due to its high protein binding.
Doxazosin should be administered with caution to patients with mild to moderate hepatic impairment (Child-Pugh Class A or B). There is no data for use in severe hepatic impairment (Child-Pugh Class C), and use in such patients is generally discouraged unless no other options exist.
> Important: Special populations require individualized medical assessment and frequent follow-up with a healthcare provider.
| Protein Binding | 98% |
| Half-life | 22 hours |
| Tmax | 2-3 hours (Immediate Release) |
| Metabolism | Hepatic (CYP3A4) |
| Excretion | Fecal 63%, Renal 9% |
Doxazosin is classified as an Alpha-1 Adrenergic Blocker. It belongs to the therapeutic categories of Antihypertensives and Benign Prostatic Hyperplasia Agents. Other drugs in this class include Terazosin, Prazosin, and the more uro-selective agent Tamsulosin.