Doxazosin is primarily used for the treatment of hypertension. The usual starting dosage for adults with hypertension is typically 1 mg taken orally once daily. Based on individual tolerance and blood pressure response, the dose may be increased to a maximum of 16 mg per day as needed.

For the treatment of BPH, the usual starting dose is 2 mg taken orally once daily, which may be adjusted based on the patient's response, possibly up to 8 mg per day.

Doxazosin can be taken with or without food, but it is often recommended to take it at bedtime to minimize the risk of dizziness or lightheadedness, particularly after the first dose due to its potential effects on blood pressure.

If you miss a dose of doxazosin and remember it within a few hours of the scheduled time, take it as soon as you remember. However, if it is almost time for your next dose, skip the missed dose and return to your normal dosing schedule; do not take two doses at the same time to compensate for the missed one.

To ensure the best therapeutic effect, it is important to follow your healthcare provider’s instructions regarding dosing and to have regular follow-up appointments to monitor blood pressure and overall treatment effectiveness. If you have any questions about how to take doxazosin or concerns regarding missed doses, consult your healthcare provider for personalized advice.

Always use this medication exactly as your clinician has told you. Check with our clinical team or your GP or pharmacist if you are not sure.

Medicines and their possible side effects can affect individual people in different ways. The following are some of the side effects that are known to be associated with this medicine. Just because a side effect is stated here, it does not mean that all people using this medicine will experience that or any side effect.

Here’s a detailed breakdown of the side effects associated with doxazosin, categorized into common, less common, rare, and important considerations:

Common Side Effects

1. Dizziness Many patients may experience dizziness or lightheadedness, particularly when standing up quickly due to the medication's blood pressure-lowering effects.

2. Fatigue: A general sense of tiredness and lack of energy may be reported by individuals taking doxazosin.

3. Headache: Mild to moderate headaches are commonly associated with doxazosin treatment.

4. Palpitations: Some individuals may experience heart palpitations or an increased awareness of their heartbeat.

5. Nausea: Gastrointestinal symptoms, including nausea, can occur among some patients.

Less Common Side Effects

1. Orthostatic Hypotension: A drop in blood pressure upon standing can lead to fainting or serious dizziness, especially after the first dose or when increasing the dosage.

2. Edema: Swelling due to fluid retention may occur, particularly in the legs and ankles.

3. Rash: Some patients may develop a skin rash or urticaria (hives), though these reactions are less common.

4. Gastrointestinal Issues: Other gastrointestinal side effects may include abdominal discomfort and constipation.

Rare Side Effects

1. Priapism: A serious condition involving prolonged and painful erections that do not resolve; this requires immediate medical attention.

2. Liver Dysfunction: Elevations in liver enzymes can occur, indicating possible liver issues that should be monitored.

3. Heart Rate Changes: Some individuals may experience significant changes in heart rate or arrhythmias.

Important Considerations

1. First-Dose Effect: Patients may experience marked hypotension when taking the first dose of doxazosin. Therefore, it is often recommended to start with a low dose, preferably at bedtime, to minimize this risk.

2. Monitoring: Regular monitoring of blood pressure is essential, especially during the initiation of therapy or after any dosage adjustments.

3. Drug Interactions: Patients should inform their healthcare provider about all medications they are taking, as doxazosin can interact with other antihypertensives or medications affecting blood pressure.

4. Caution in Patients with a History of Prostate Cancer: Since doxazosin is used to relieve symptoms of benign prostatic hyperplasia (BPH), caution is advised in patients with prostate cancer, as its effects and safety profile require careful evaluation.

For full information on side effects and correct use, see the patient information leaflet. If any side effects concern you, or you are experiencing any of the side effects mentioned in the patient information leaflet whilst taking this medication, please contact our clinical team or speak to your GP.

Cautions

1. Orthostatic Hypotension: Doxazosin can cause significant decreases in blood pressure, especially after the first dose. It is important to monitor patients for symptoms of
lightheadedness or dizziness when standing up, particularly in the elderly or those on other antihypertensive medications.

2. Caution in Patients with Existing Cardiovascular Conditions: Doxazosin should be used cautiously in patients with a history of heart disease, especially those with unstable angina or congestive heart failure, as the medication may affect cardiac output.

3. Liver Impairment: Caution is advised in patients with hepatic impairment, as the metabolism of doxazosin can be affected, potentially requiring dosage adjustments.

4. Pregnancy and Lactation: The use of doxazosin during pregnancy should be approached with caution. It should be prescribed only if the benefits outweigh the risks. The effects on breastfeeding are not well-established, so caution is warranted.

5. Elderly Patients: Older adults may be more sensitive to the blood pressure-lowering effects of doxazosin and may require careful dosing and monitoring.

Warnings

1. First-Dose Effect: Patients should be informed about the first-dose phenomenon, which can lead to pronounced hypotension. It is usually recommended to take the first dose at bedtime to minimize the risk of dizziness or fainting.

2. Priapism: Doxazosin is associated with a risk of priapism, a prolonged and painful erection that can lead to serious complications if not treated promptly. Patients should be counseled about this rare but serious potential side effect.

3. Drug Interactions: Doxazosin may interact with other medications, including other antihypertensives, phosphodiesterase type 5 inhibitors (e.g., sildenafil), and medications affecting the liver enzymes responsible for its metabolism. Patients should inform their healthcare provider about all their current medications.

4. Monitoring: Regular monitoring of blood pressure is essential, especially during the initiation of therapy and after any dose adjustments.

Get emergency medical help if you have signs of an allergic reaction to this medication. These include:

• Hives
• Dizziness
• Fast or pounding heartbeats
• Wheezing
• Difficult breathing
• Swelling of your face, lips, tongue, or throat.

It is important that you let us know which prescription, over-the-counter medicines and recreational drugs you are currently taking. You must also tell us about any other medical conditions that you currently have (or had in the past). This will help us ensure the prescribed medication is safe and appropriate for you to take.

For full information on warnings, medication interactions and contraindications, refer to the Patient Information Leaflet. Please read all packaging and the Patient Information Leaflet before taking any new medicine and inform our clinical team or your GP of medicines you are taking or intend to take.