Cardura XL

Cardura XL is an oral blood pressure medication in extended-release formula containing Doxazosin as its active ingredient. It belongs to the Alpha-1 Adrenergic Blocker drug class and is manufactured by Pfizer.

Doxazosin works by blocking Alpha-1 adrenergic receptors on the smooth muscles of blood vessels and the prostate gland. This causes blood vessels to relax, allowing blood to flow more easily and reducing blood pressure. It also relaxes muscles at the bladder neck and prostate, improving urinary flow.

The XL formula uses GITS (Gastrointestinal Therapeutic System) technology to release the drug consistently over 24 hours, reducing blood level fluctuations, providing steady blood pressure control, and minimising side effects from sudden peak drug levels.

Hypertension (High Blood Pressure): Cardura XL helps reduce both systolic and diastolic blood pressure. It is used as an add-on therapy with other blood pressure medications, particularly for resistant hypertension that is not adequately controlled with first-line treatments.

Benign Prostatic Hyperplasia (BPH): Relieves urinary symptoms including difficulty urinating, frequent urination (especially at night/nocturia), weak urine stream, and incomplete bladder emptying. It improves urine flow rate. However, Doxazosin does not shrink the prostate, so surgery may still be needed in the future if symptoms worsen.

Dual benefit for men with both conditions: Cardura XL is one of the few blood pressure medications that can treat both hypertension and BPH symptoms simultaneously, reducing the total number of medications needed.

Starting dose: Take 4 mg once daily with breakfast. Swallow whole — do not crush, chew, or split as this destroys the Extended Release delivery system.

Dose adjustment: Your doctor may increase to 8 mg once daily if needed, with a minimum interval of 3–4 weeks. Maximum recommended dose is 8 mg/day.

Elderly patients: Start at the lowest dose and titrate cautiously, as there is a higher risk of orthostatic hypotension.

If you miss a dose: Skip the missed dose and take the next one at the usual time. Never take a double dose. If you have missed several days, restart at 4 mg to prevent dizziness.

Important: Always take with breakfast, as food improves absorption and reduces side effects.

Common side effects:

• Dizziness, lightheadedness — the most frequent side effect, especially when first starting the medication, caused by blood pressure reduction
• Headache, fatigue
• Swelling of ankles and feet (peripheral oedema)
• Nausea, abdominal pain
• Runny nose, nasal congestion

Serious side effects (stop taking and seek medical attention):

• Fainting upon standing (orthostatic hypotension) — especially within the first 2–6 hours after starting
• Rapid heartbeat (tachycardia), chest pain
• Severe allergic reaction: rash, hives, swelling of face/lips/throat, difficulty breathing
• Severe swelling (may indicate heart failure)

Note: The ALLHAT study found that Doxazosin may increase the risk of heart failure compared to diuretics, so it is not recommended as a first-line blood pressure medication.

Do not use:

• Allergy to Doxazosin or other quinazoline derivatives (e.g., Prazosin, Terazosin)
• Severe liver disease
• History of orthostatic hypotension
• Gastrointestinal stricture — do not use XL formula as the tablet shell may cause obstruction

Use with caution:

• Heart disease — especially heart failure; use with caution
• Planned cataract surgery — inform your ophthalmologist, as Doxazosin may cause Intraoperative Floppy Iris Syndrome (IFIS)
• Pregnancy and breastfeeding — insufficient safety data; consult doctor
• Elderly patients — higher risk of fainting; stand up slowly
• Avoid alcohol during treatment as it may worsen dizziness

Cardura XL vs. Cazosin: Same active ingredient (Doxazosin). Cardura XL is the originator brand by Pfizer in Extended Release at a higher price. Cazosin is a quality-equivalent generic in Immediate Release, Thai FDA-registered at a more accessible price.

Cardura XL vs. Terazosin: Both are alpha-blockers for hypertension and BPH. Terazosin has a shorter half-life but can still be taken once daily. Generally more affordable than Cardura XL.

Cardura XL vs. Tamsulosin: Tamsulosin is more selective for Alpha-1A receptors, making it primarily a BPH treatment with less blood pressure-lowering effect. Cardura XL treats both conditions, ideal for patients with both hypertension and BPH.

Medications requiring special caution:

• PDE-5 Inhibitors (Viagra, Cialis, Sidegra) — Do not combine without medical advice; may cause dangerously low blood pressure. Separate doses by at least 4 hours.
• Other blood pressure medications — Can be used together but risk of hypotension; doctor will adjust dosages.
• NSAIDs (Ibuprofen, Diclofenac) — May reduce the blood pressure-lowering effect of Doxazosin.
• Clarithromycin, Ketoconazole — These CYP3A4 inhibitors increase Doxazosin blood levels.

Other alpha-blockers (e.g., Tamsulosin) — Do not combine; significantly increases the risk of severe hypotension.

Doxazosin has a half-life of approximately 22 hours, long enough for once-daily dosing. The XL formula is designed for slow, consistent drug release. Peak blood levels are reached within 8–9 hours after taking.

For hypertension: Blood pressure reduction typically begins within 1–2 weeks, but may take 4–6 weeks for full effect.

For BPH: Urinary symptoms usually start improving within 1–2 weeks, but up to 4 weeks may be needed for noticeable improvement.

If symptoms haven't improved after 4 weeks, consult your doctor about dose adjustment or alternative treatment.

Cardura XL is a pharmacist-dispensed medication. You can order online from Intimo Life.

Can I buy Cardura XL online?

Yes. Order through Intimo Life — select the product, consult with a licensed pharmacist online, and receive your medication at home.

Do I need a prescription?

A doctor's prescription is not required, but the medication must be dispensed by a licensed pharmacist. At Intimo Life, our pharmacist will review your symptoms and health history to confirm suitability before shipping.

How does Intimo Life ship orders?

We deliver nationwide in Thailand with discreet packaging — no product names on the outside.