Many men taking lisinopril for high blood pressure wonder whether they can safely use sildenafil for erectile dysfunction. Lisinopril is an angiotensin-converting enzyme (ACE) inhibitor that lowers blood pressure by blocking angiotensin II production, whilst sildenafil is a phosphodiesterase type 5 (PDE5) inhibitor that relaxes blood vessels to improve blood flow. Both medications can usually be taken together with appropriate medical supervision, but the combination requires careful consideration due to their shared blood pressure-lowering effects. This article examines the interaction between lisinopril and sildenafil, safety considerations, and how to manage this combination effectively under GP guidance.

Does Lisinopril Interact with Sildenafil?

Lisinopril and sildenafil can usually be taken together with caution, but you should always discuss this combination with your GP. Lisinopril is an angiotensin-converting enzyme (ACE) inhibitor used to treat hypertension and heart failure, whilst sildenafil is a phosphodiesterase type 5 (PDE5) inhibitor primarily prescribed for erectile dysfunction and pulmonary arterial hypertension.

Both medications work through different mechanisms but share a common effect: they both lower blood pressure. Lisinopril reduces blood pressure by blocking the production of angiotensin II, a hormone that causes blood vessels to narrow. Sildenafil works by relaxing smooth muscle in blood vessels through increased cyclic guanosine monophosphate (cGMP) levels, which improves blood flow to specific areas of the body.

The primary concern with this combination is additive hypotension — an excessive drop in blood pressure that can cause dizziness, light-headedness, fainting, or in severe cases, cardiovascular complications. The Medicines and Healthcare products Regulatory Agency (MHRA) and the British National Formulary (BNF) note that whilst this combination is not contraindicated, patients should be monitored for symptomatic hypotension, particularly when initiating treatment or adjusting doses.

Clinical studies have shown that the blood pressure-lowering effect of sildenafil is generally modest in most patients, typically reducing systolic blood pressure by 8–10 mmHg. However, individual responses vary considerably, and patients with already well-controlled or low blood pressure may be at higher risk of symptomatic hypotension.

It is essential that any man taking lisinopril who is considering sildenafil discusses this with his GP or prescriber before starting treatment. Sildenafil must never be taken with nitrates (including GTN), nicorandil, or riociguat as this combination can cause dangerous drops in blood pressure. If you also take alpha-blockers, your doctor will likely start sildenafil at a lower dose (25 mg).

Safety Considerations When Taking Both Medications

When lisinopril and sildenafil are prescribed together, several safety considerations must be addressed to minimise risks. The most significant concern remains the potential for symptomatic hypotension, particularly during the first few doses of sildenafil or following dose increases of either medication.

Patients should be aware of the signs and symptoms of low blood pressure, which include:

• Dizziness or light-headedness, especially when standing up quickly

• Feeling faint or actually fainting

• Blurred vision

• Unusual tiredness or weakness

• Nausea

• Confusion or difficulty concentrating

Be cautious with postural changes, particularly within the first few hours after taking sildenafil. Sildenafil reaches peak plasma concentrations approximately 60 minutes after oral administration, with effects lasting 4–5 hours. Avoid standing up quickly, especially after sitting or lying down for prolonged periods.

Alcohol consumption should be limited when taking this combination, as alcohol independently causes vasodilation and can further lower blood pressure. The NHS advises that men taking medications for erectile dysfunction should drink alcohol only in moderation.

Certain patient groups require additional caution, including those with:

• Pre-existing cardiovascular disease

• Left ventricular outflow obstruction (such as aortic stenosis)

• Autonomic dysfunction

• Volume depletion or dehydration

• Patients taking multiple antihypertensive medications

Important safety warnings:

• Seek immediate medical attention if you experience an erection lasting 4 hours or longer (priapism)

• Stop taking sildenafil and seek urgent medical care if you experience sudden vision or hearing loss

• If you develop chest pain within 24 hours of taking sildenafil, tell emergency responders you've taken it, as nitrate medications (including GTN) should not be used

• If you experience severe dizziness or fainting, seek immediate medical attention

Patients over 65, those with liver problems, or those with severe kidney disease may need a lower starting dose of sildenafil.

What to Tell Your Doctor Before Using Sildenafil

A comprehensive medical discussion with your GP or prescriber is essential before starting sildenafil, particularly if you are taking lisinopril or other blood pressure medications. Full disclosure of your medical history and current medications enables your doctor to assess whether sildenafil is safe and appropriate for you.

Key information to share with your doctor includes:

• All current medications, including prescription drugs, over-the-counter medicines, and herbal supplements. This is particularly important as some medications are absolutely contraindicated with sildenafil, including all nitrates (such as glyceryl trinitrate), nicorandil, riociguat, and recreational 'poppers' (amyl nitrite)

• Your complete cardiovascular history, including any history of heart attack, stroke, arrhythmias, or heart failure

• Current blood pressure readings and how well controlled your hypertension is on lisinopril

• Any history of hypotension or episodes of dizziness and fainting

• Other medical conditions, particularly kidney or liver disease, which can affect how sildenafil is metabolised

• Any anatomical deformation of the penis or conditions predisposing to priapism (such as sickle cell disease, multiple myeloma, or leukaemia)

• History of vision problems, particularly non-arteritic anterior ischaemic optic neuropathy (NAION) or retinitis pigmentosa

Your doctor will likely check your blood pressure during the consultation and may recommend monitoring at home, particularly when you first start taking sildenafil. According to NICE guidance, cardiovascular risk factors should be assessed and blood pressure should be reasonably controlled before initiating treatment for erectile dysfunction.

Be honest about your erectile dysfunction symptoms and their impact on your quality of life. Your GP can assess whether sildenafil is the most appropriate treatment or whether alternative options might be more suitable given your cardiovascular profile. In some cases, your doctor may recommend starting with a lower dose of sildenafil (25 mg rather than 50 mg) to assess your tolerance to the medication.

Tell your doctor if you take medicines that might affect sildenafil levels, such as certain antibiotics (clarithromycin), antifungals (ketoconazole), or HIV medications (ritonavir). These can increase sildenafil exposure and may require dose adjustments. Also mention if you drink grapefruit juice, which can increase sildenafil levels.

Never obtain sildenafil from unregulated sources. Counterfeit medications purchased online may contain incorrect doses or harmful substances and lack proper pharmaceutical quality control.

Managing Blood Pressure While Taking Erectile Dysfunction Treatment

Effective blood pressure management remains the priority when taking lisinopril alongside sildenafil for erectile dysfunction. Maintaining optimal blood pressure control not only reduces cardiovascular risk but also minimises the likelihood of problematic interactions with erectile dysfunction treatments.

Regular blood pressure monitoring is essential. The NHS recommends that patients with hypertension monitor their blood pressure regularly, either at home using a validated device (from the British and Irish Hypertension Society list) or through regular GP appointments. When starting sildenafil, more frequent monitoring may be advisable, particularly in the first few weeks. For home monitoring, take readings while seated with your back supported, after resting for 5 minutes. Take 2-3 readings, 1 minute apart, and record all values. Keep a record of your readings, noting the time of day and any symptoms experienced, to share with your healthcare team.

Lifestyle modifications support both blood pressure control and erectile function:

• Maintain a healthy weight — obesity is a risk factor for both hypertension and erectile dysfunction

• Follow a balanced diet low in salt and rich in fruits, vegetables, and whole grains (following the NHS Eatwell Guide and Mediterranean-style eating patterns)

• Exercise regularly — aim for at least 150 minutes of moderate-intensity activity weekly, as recommended by NICE

• Limit alcohol consumption to within recommended guidelines (14 units per week)

• Stop smoking — smoking damages blood vessels and worsens both conditions

• Manage stress through relaxation techniques, adequate sleep, and psychological support if needed

Medication adherence is crucial. Take lisinopril exactly as prescribed, typically once daily at the same time each day. Do not adjust your blood pressure medication dose without consulting your GP, even if you experience mild dizziness when taking sildenafil.

Attend regular review appointments with your GP or practice nurse. NICE recommends annual reviews for patients with hypertension (NG136), but more frequent monitoring may be necessary when taking multiple medications affecting blood pressure. These appointments allow for dose adjustments, assessment of treatment effectiveness, monitoring of kidney function and electrolytes, and discussion of any concerns.

If erectile dysfunction persists despite treatment or if you experience adverse effects from sildenafil, discuss alternative options with your doctor. Other PDE5 inhibitors (such as tadalafil or vardenafil) have the same contraindications with nitrates but may suit your needs better. Note that tadalafil has a longer duration of action, which means the potential for blood pressure interaction lasts longer. Non-medication options include vacuum erection devices and psychosexual therapy.

If you experience any suspected adverse reactions to either medication, report them through the MHRA Yellow Card scheme.

Frequently Asked Questions