What drugs should not be taken with alfuzosin?

October 14, 2025 •

3 min read

Alfuzosin has more than 300 known drug interactions, with many being major [1.2.3]. Understanding what drugs should not be taken with alfuzosin is critical for avoiding serious side effects like severe low blood pressure and fainting [1.4.3, 1.8.1].

Quick Summary

A detailed overview of medications that have dangerous interactions with alfuzosin. Key contraindications include strong CYP3A4 inhibitors, other alpha-blockers, and phosphodiesterase-5 (PDE5) inhibitors, which can cause symptomatic hypotension [1.2.2].

Key Points

CYP3A4 Inhibitors: Taking alfuzosin with strong CYP3A4 inhibitors like ketoconazole or ritonavir is contraindicated as it dangerously increases alfuzosin blood levels [1.2.2].
Other Alpha-Blockers: Combining alfuzosin with other alpha-blockers such as tamsulosin or doxazosin should be avoided to prevent severe low blood pressure [1.4.3].
Blood Pressure Medications: Use caution when taking alfuzosin with antihypertensive drugs, as the combination can increase the risk of postural hypotension and fainting [1.8.4].
ED Medications (PDE5 Inhibitors): Co-administration with drugs like sildenafil or tadalafil can cause symptomatic hypotension and requires medical guidance [1.2.2].
Alcohol: Drinking alcohol while taking alfuzosin can enhance its blood-pressure-lowering effects, leading to increased dizziness and fainting risk [1.10.2, 1.10.3].
Liver Health: Alfuzosin is contraindicated in patients with moderate to severe liver impairment because the drug is primarily metabolized by the liver [1.4.1].
Always Disclose Medications: Inform your healthcare provider of all medications, supplements, and herbal products you use to prevent harmful interactions [1.3.1].

Understanding Alfuzosin

Alfuzosin is an alpha-adrenergic antagonist used to treat the symptoms of benign prostatic hyperplasia (BPH) in adult men [1.5.2, 1.6.1]. It works by relaxing the muscles in the prostate and bladder neck, which improves urine flow and reduces BPH symptoms [1.5.2, 1.5.3]. However, its effectiveness can be dangerously altered when combined with other medications due to its metabolism process and its effects on blood pressure [1.4.3, 1.5.5]. Alfuzosin is extensively metabolized by the liver, with the enzyme CYP3A4 being the principal one involved in this process [1.5.1]. Therefore, any drug that inhibits this enzyme can lead to increased levels of alfuzosin in the blood, heightening the risk of adverse effects [1.4.3].

Major Drug Interactions: Contraindicated Medications

Certain medications are strictly contraindicated, meaning you should never take them with alfuzosin due to the risk of serious, life-threatening reactions [1.2.3]. The primary reason for these contraindications is the significant impact these drugs have on the CYP3A4 enzyme system [1.5.1].

Strong CYP3A4 Inhibitors

These drugs block the CYP3A4 enzyme, which is responsible for breaking down alfuzosin in the body [1.5.1]. Blocking this enzyme leads to dangerously high levels of alfuzosin, increasing the risk of severe side effects like hypotension (low blood pressure) [1.2.2].

Examples of strong CYP3A4 inhibitors include [1.2.1, 1.2.2, 1.7.1]:

Antifungal medications (e.g., ketoconazole, itraconazole)
HIV protease inhibitors (e.g., ritonavir, atazanavir, indinavir)
Certain antibiotics (e.g., clarithromycin, telithromycin)
The antidepressant nefazodone [1.2.3]

Other Alpha-Blockers

Alfuzosin itself is an alpha-blocker. Taking it with other medications in the same class can lead to an additive effect, causing a severe drop in blood pressure [1.4.3]. Interactions may be expected, and using them in combination is not recommended [1.2.2].

Examples of other alpha-blockers include [1.3.4, 1.4.3]:

Doxazosin
Prazosin
Tamsulosin
Terazosin

Drugs Requiring Caution and Monitoring

Beyond the drugs that are strictly forbidden, a wide range of medications can interact with alfuzosin, requiring careful monitoring by a healthcare professional [1.3.3]. These interactions can potentiate the blood-pressure-lowering effects of alfuzosin or increase the risk of other side effects [1.8.4].

Antihypertensive Medications and Nitrates

When alfuzosin is taken with other drugs designed to lower blood pressure, there is an increased risk of postural hypotension (a sudden drop in blood pressure when standing up) and syncope (fainting) [1.8.4]. Your doctor may need to adjust your dose or monitor your blood pressure more frequently [1.10.2].

Examples of these drugs include [1.4.3, 1.8.1]:

Beta-blockers (e.g., atenolol, metoprolol) [1.8.2]
Calcium channel blockers (e.g., amlodipine, diltiazem) [1.8.3]
Aldosterone antagonists (e.g., spironolactone)
Nitrates used for chest pain

Phosphodiesterase-5 (PDE5) Inhibitors

Used to treat erectile dysfunction (ED), PDE5 inhibitors are also vasodilators, meaning they widen blood vessels and can lower blood pressure [1.2.2]. Combining them with alfuzosin can lead to symptomatic hypotension [1.2.2]. Caution is advised, and your doctor will guide you on safe usage [1.8.4].

Examples of PDE5 inhibitors include [1.8.1]:

Sildenafil
Tadalafil
Vardenafil
Avanafil

Comparison of Key Interacting Drug Classes


Drug Class	Interaction Risk	Potential Side Effect	Management
Strong CYP3A4 Inhibitors	Major (Contraindicated)	Dangerously high alfuzosin levels, severe hypotension [1.2.2]	Avoid combination completely [1.2.2].
Other Alpha-Blockers	Major (Contraindicated)	Additive effect, severe hypotension, fainting [1.4.3]	Do not use in combination [1.2.2].
Antihypertensives	Moderate to Major	Increased risk of low blood pressure and fainting [1.8.4]	Close monitoring, potential dose adjustment [1.10.2].
PDE5 Inhibitors	Moderate to Major	Symptomatic low blood pressure [1.2.2]	Use with caution under medical advice [1.8.4].
Alcohol	Moderate	Increased dizziness and risk of low blood pressure [1.10.2]	Avoid or limit alcohol intake [1.10.4].

Conclusion

To ensure safety while taking alfuzosin, it is crucial to provide your doctor and pharmacist with a complete list of all medications, supplements, and herbal products you are taking [1.3.1]. Due to the high number of potential interactions, especially with drugs affecting blood pressure and liver enzymes, medical supervision is essential [1.3.1, 1.4.3]. Do not start or stop any medication without first consulting your healthcare provider. Taking alfuzosin as prescribed and avoiding contraindicated drugs are key steps to managing BPH symptoms safely and effectively.

For more detailed information, consult the official prescribing information available from the U.S. Food & Drug Administration [1.7.3].

Frequently Asked Questions

Alfuzosin is primarily metabolized by the CYP3A4 enzyme in the liver. Many drugs can inhibit or induce this enzyme, which significantly alters the concentration of alfuzosin in the blood, leading to potential toxicity or reduced efficacy [1.5.1, 1.5.5].

Combining alfuzosin with blood pressure medications like amlodipine can increase the risk of low blood pressure (hypotension) [1.8.3]. It requires caution and you should be monitored by your doctor, who may need to adjust your dosage [1.8.4].

Caution is advised when taking PDE5 inhibitors like sildenafil (Viagra) with alfuzosin. Both are vasodilators that lower blood pressure, and their combined use can lead to a significant drop in blood pressure [1.2.2, 1.8.4].

Drinking alcohol with alfuzosin can lower your blood pressure and increase side effects like dizziness and feeling faint, especially when standing up. It is recommended to avoid or limit alcohol consumption [1.10.2, 1.10.4].

Since alfuzosin and tamsulosin are both alpha-blockers, taking them together can cause an additive effect, leading to a severe drop in blood pressure. Combining them is not recommended [1.4.3, 1.2.2].

You should avoid potent CYP3A4-inhibiting antibiotics like clarithromycin and telithromycin, as they can cause dangerously high levels of alfuzosin in your system [1.2.1, 1.7.1].

Yes, grapefruit juice can interact with alfuzosin [1.3.4]. Like many other drugs metabolized by CYP3A4, grapefruit juice can inhibit the enzyme and increase the concentration of alfuzosin in the blood, raising the risk of side effects.