Does sildenafil make your heart race? Sildenafil (Viagra) is a phosphodiesterase type 5 (PDE5) inhibitor widely prescribed for erectile dysfunction and pulmonary arterial hypertension. Whilst this medication primarily works by relaxing blood vessels to improve blood flow, many patients wonder about its effects on heart rate. Clinical evidence shows sildenafil typically causes a modest decrease in blood pressure rather than directly increasing heart rate, though some individuals may experience mild compensatory changes or palpitations. Understanding these cardiovascular effects, recognising when symptoms require medical attention, and following NHS guidance ensures safe, effective use of this medication.

Does Sildenafil Make Your Heart Race?

Sildenafil, commonly known by the brand name Viagra, is a phosphodiesterase type 5 (PDE5) inhibitor primarily prescribed for erectile dysfunction and pulmonary arterial hypertension. Many patients wonder whether this medication can cause their heart to race or palpitations to occur.

Understanding the cardiovascular effects: Sildenafil works by relaxing blood vessels and improving blood flow, which can lead to modest changes in heart rate and blood pressure. Clinical studies show that sildenafil typically causes a small decrease in blood pressure (around 8-10 mmHg systolic) rather than directly increasing heart rate. However, some patients may experience a compensatory mild increase in heart rate as the body responds to lower blood pressure. This is generally a normal physiological response and not a cause for alarm in healthy individuals.

Cardiovascular side effects reported in clinical trials include:

• Flushing (warmth and redness in the face and chest) - common

• Headache - common

• Dizziness or light-headedness - common

• Palpitations (awareness of heartbeat) - uncommon

• Nasal congestion - common

• Dyspepsia (indigestion) - common

Whilst tachycardia (abnormally fast heart rate) is uncommon with sildenafil, some patients may perceive their heart racing due to anxiety about sexual performance, the physical exertion of sexual activity itself, or heightened awareness of normal cardiovascular changes. Clinical trials have not shown increased risk of serious cardiovascular events compared to placebo, though rare cases of arrhythmias have been reported in post-marketing surveillance, particularly in patients with pre-existing cardiac disease. Cardiovascular assessment is recommended before prescribing, particularly in patients with risk factors for heart disease, in line with NICE Clinical Knowledge Summary guidance.

When to Seek Medical Help for Heart Symptoms

Whilst sildenafil is generally well-tolerated, certain cardiovascular symptoms warrant immediate medical attention. Understanding when to seek help is crucial for patient safety and can prevent serious complications.

Seek emergency medical help (call 999) if you experience:

• Chest pain or pressure during or after taking sildenafil, particularly if it spreads to your arms, neck, or jaw

• Severe shortness of breath or difficulty breathing

• Very rapid or worsening heart rate at rest, particularly with chest pain, breathlessness, or dizziness

• Fainting or loss of consciousness

• Symptoms suggestive of a heart attack or stroke

• Sudden decrease or loss of hearing

Contact your GP or NHS 111 within 24 hours if you notice:

• Persistent palpitations that don't settle after resting

• New or worsening dizziness when standing

• Unusual fatigue or weakness following sildenafil use

• Swelling in your legs or ankles

• Any cardiovascular symptoms that concern you or differ from your usual experience

Important safety consideration: If you experience chest pain after taking sildenafil, do not use GTN spray or nitrate medications, as the combination can cause a dangerous drop in blood pressure. Inform emergency services or healthcare professionals that you have taken sildenafil so they can provide appropriate treatment.

Patients should report any suspected side effects to the MHRA Yellow Card scheme, which allows patients and healthcare professionals to contribute to ongoing medication safety monitoring. Regular review with your GP is advisable if you're taking sildenafil long-term, particularly if you have cardiovascular risk factors or develop new symptoms.

Who Should Avoid Sildenafil Due to Heart Concerns

Sildenafil is contraindicated in certain patient groups due to potential cardiovascular risks. A thorough medical assessment is essential before initiating treatment to identify individuals who should avoid this medication.

Absolute contraindications (sildenafil must not be used):

• Patients taking nitrates (such as GTN, isosorbide mononitrate, or isosorbide dinitrate) for angina or heart conditions — the combination can cause life-threatening hypotension

• Those using nicorandil, another anti-anginal medication

• Patients taking riociguat for pulmonary hypertension

• Recent myocardial infarction (heart attack) within the past 6 months

• Recent stroke within the past 6 months

• Men for whom sexual activity is inadvisable due to underlying cardiovascular status

• Unstable angina or angina occurring during sexual intercourse

• Severe hypotension (blood pressure <90/50 mmHg)

Use with caution:

• Uncontrolled hypertension (requires optimisation before sexual activity/PDE5 inhibitors)

• Conditions predisposing to priapism (e.g., sickle cell anaemia, multiple myeloma, leukaemia)

• Anatomical deformation of the penis

• Severe hepatic or renal impairment (dose adjustment may be required)

• Hereditary degenerative retinal disorders (use not recommended)

• History of non-arteritic anterior ischaemic optic neuropathy (NAION) (use with caution)

Cardiovascular risk assessment before prescribing sildenafil for erectile dysfunction is recommended. This should include evaluation of cardiac history, current medications, blood pressure measurement, and consideration of exercise tolerance. The Princeton consensus (not a NICE recommendation) suggests that patients able to manage moderate physical activity (equivalent to climbing two flights of stairs) may be suitable candidates for sildenafil, though individual assessment is essential. Men with multiple cardiovascular risk factors should undergo comprehensive evaluation, potentially including cardiology referral, before commencing treatment.

Safe Use of Sildenafil: NHS and MHRA Guidance

The safe and effective use of sildenafil requires adherence to prescribing guidelines and patient education about proper administration. Both the NHS and MHRA provide clear recommendations to optimise safety and therapeutic outcomes.

Dosing and administration:

• Standard starting dose for erectile dysfunction: 50mg, taken approximately one hour before sexual activity

• Dose may be adjusted to 25mg or increased to maximum 100mg based on efficacy and tolerability

• Maximum frequency: once daily

• For pulmonary arterial hypertension, dosing differs (typically 20mg three times daily) and should follow specialist guidance

• Sildenafil can be taken with or without food, though high-fat meals may delay absorption

• Avoid grapefruit juice, which can increase sildenafil levels and side effects

Important drug interactions:

• CYP3A4 inhibitors: With ritonavir, do not exceed 25mg in 48 hours; with potent inhibitors (e.g., ketoconazole, itraconazole, erythromycin, clarithromycin), consider 25mg starting dose

• Alpha-blockers: Ensure patient is stable on alpha-blocker before starting sildenafil; start at 25mg and monitor for postural hypotension; consider separating doses with non-selective alpha-blockers such as doxazosin

• Recreational nitrates: Avoid 'poppers' (amyl nitrite) which can cause dangerous drops in blood pressure when combined with sildenafil

Safety considerations:

• Alcohol moderation: Excessive alcohol can impair erectile function and increase the risk of side effects such as dizziness and hypotension

• Priapism warning: Seek immediate medical attention for erections lasting longer than 4 hours, as this constitutes a medical emergency

• Vision/hearing changes: Rare cases of sudden vision or hearing loss have been reported; discontinue sildenafil and seek urgent medical advice if these occur

NHS prescribing pathway: Sildenafil for erectile dysfunction is available on NHS prescription under Selected List Scheme (SLS) arrangements for specific medical conditions (such as diabetes, prostate cancer treatment, or severe distress). SLS endorsement is required, and typically limited to one treatment per week. Viagra Connect (sildenafil 50mg) is available as a Pharmacy medicine following pharmacist assessment. Private prescriptions are common, but patients should ensure they obtain medication from registered UK pharmacies to avoid counterfeit products.

MHRA recommendations emphasise purchasing sildenafil only from legitimate sources. Counterfeit medications purchased online may contain incorrect doses, harmful substances, or no active ingredient, posing serious health risks. The MHRA advises checking that online pharmacies display the registered pharmacy logo and are registered with the General Pharmaceutical Council (GPhC). Regular medication review with your GP or prescriber ensures ongoing safety and allows adjustment of treatment as needed.

Frequently Asked Questions