Sildenafil Safety Information

Sildenafil is a prescription medication used to treat erectile dysfunction (ED). Like any medication, it is safest when used under the guidance of a licensed clinician, with a complete review of your health history and current medications. Prescription required. Eligibility determined by a licensed clinician.

Quick safety checklist (read this first)

Do NOT take sildenafil if you:

·    Take nitrates for chest pain (angina) or use recreational “poppers” (often contain nitrites/nitrates). This combination can cause a dangerous drop in blood pressure.

·         Take riociguat (Adempas®).

·         Have been told sexual activity is not advisable due to your cardiovascular status.

·         Get urgent medical help if you have:

·         An erection lasting more than 4 hours (priapism).

·         Chest pain, fainting, severe dizziness, or sudden shortness of breath.

·         Sudden vision loss or sudden hearing loss (sometimes with ringing/dizziness).

Who should avoid sildenafil (or needs extra caution)

Tell your clinician if you have—or have had—any of the following. These may affect whether sildenafil is appropriate and what dose is safest:

·         Heart disease, prior heart attack or stroke, rhythm issues, or chest pain with exertion

·         Low blood pressure or frequent dizziness/fainting

·         Bleeding disorders or history of stomach ulcer

·         Certain eye conditions (including NAION history or retinitis pigmentosa)

·         Conditions that increase priapism risk (e.g., sickle cell anemia, leukemia, multiple myeloma)

·         Penile curvature / Peyronie’s disease

·         Kidney or liver disease (may require a lower starting dose)

Medication interactions that matter most

Sildenafil can interact with other drugs and supplements. Always list everything you take (prescription, over-the-counter, supplements, and recreational substances).

·         Interactions that can be dangerous:

·         Nitrates / nitrites (nitroglycerin, isosorbide, “poppers”) → risk of severe hypotension/fainting

·         Riociguat (Adempas®) → not recommended/contraindicated with sildenafil

·         Alpha-blockers (often for BPH or blood pressure) and other blood pressure medications → may increase dizziness or low blood pressure risk

·         Strong CYP3A4 inhibitors (some HIV meds like ritonavir, some antifungals like ketoconazole, certain antibiotics) → can raise sildenafil levels; dosing adjustments may be needed

·         Food/supplement considerations:

·         Grapefruit / grapefruit juice may affect how your body processes sildenafil—ask your clinician.

·         Disclose supplements like St. John’s wort (possible interactions).

How to use sildenafil safely

·         Take only as prescribed and do not exceed your prescribed dose.

·         For ED, sildenafil is typically taken as needed; maximum dosing frequency is once per day.

·         Many people take it 30 minutes to 4 hours before sexual activity (individual response varies).

·         Do not combine with other ED medications unless your clinician specifically advises it.

·         If you need emergency care for a heart issue, tell the clinician when you last took sildenafil.

Common side effects

·         Common side effects may include:

·         Headache

·         Flushing

·         Indigestion

·         Nasal congestion

·         Dizziness

·         Nausea

·         Back or muscle pain

·         Mild vision changes

If side effects are bothersome or persistent, contact your prescribing clinician.

Serious side effects: stop and seek care

·         Erection lasting more than 4 hours or a painful erection

·         Sudden vision loss (possible NAION)

·         Sudden hearing loss (sometimes with ringing/dizziness)

·         Chest pain, fainting, severe dizziness, or symptoms of an allergic reaction (swelling, trouble breathing)

Frequently asked questions

How long does sildenafil last?

Many people notice effects for about 4 hours, though it can remain in your system longer. Response varies by person.

Is sildenafil generally safe?

Sildenafil is often well tolerated when prescribed appropriately, but it can be unsafe with certain medications (especially nitrates/poppers) or certain heart conditions.

Can I take sildenafil if I’m on blood pressure medication?

Sometimes yes, but it depends on the specific medication and your blood pressure control. Your clinician may recommend dose adjustments and monitoring.

Should I tell my clinician about supplements or recreational drugs?

Yes. Supplements and recreational substances can interact. “Poppers” are especially risky and should not be used with sildenafil.

Telehealth safety note from InstaRx:

We are built for fast, high-quality care—but safety comes first:

1.       Complete a secure intake

2.       A licensed clinician reviews for appropriateness and interactions

3.       If eligible, a prescription is issued and medication is dispensed through a licensed pharmacy partner

 Not for emergency use. If you have severe symptoms, call 911 or go to the nearest emergency department.

Important Safety Information

Sildenafil is not appropriate for everyone. Do not use with nitrates/nitrites or riociguat. Seek emergency care for chest pain, fainting, sudden vision/hearing loss, or an erection lasting longer than 4 hours. This page is for education only and does not replace medical advice from a clinician.