Sildenafil: Uses, Side Effects, & FAQs
Sildenafil is a prescription medicine used to treat erectile dysfunction (ED) in men.
It works by increasing blood flow to the penis, helping you achieve and maintain an erection during sexual activity.
In this guide, you'll learn how sildenafil works, how to take it correctly, what side effects to watch for, and the importance of consulting a licensed doctor before starting treatment.
How Sildenafil Works
Sildenafil helps treat erectile dysfunction by improving blood flow to the penis. It blocks an enzyme (PDE5) that normally restricts circulation, allowing the blood vessels to relax and open up when you're sexually aroused.1
Sildenafil works best when combined with sexual stimulation, and with sildenafil supporting your blood flow, it becomes easier to get and sustain an erection.
It’s designed to support your natural response, giving you more confidence and control when the moment happens.
How to take Sildenafil
Sildenafil is taken as needed before sex. Follow these instructions for safe and effective use:
Take 1 tablet about 30 minutes to 1 hour before sexual activity.
Sildenafil should be taken on an empty stomach and not mixed with alcohol, grapefruit juice, or high-fat foods, which could hinder its effectiveness and cause side effects.
Its effects commonly last between 4 to 6 hours. Do not take more than 1 dose in 24 hours.
Your doctor may adjust your dose to 50 mg or 100 mg, depending on how your body respond
Who Can Take Sildenafil
Sildenafil is intended for adult men experiencing erectile dysfunction. It may be right for you if:
You have difficulty getting or keeping an erection.
You want a safe, effective, doctor-approved solution for ED.
You’re not currently taking nitrate-based medications.
Sildenafil is not recommended for:
Women or anyone under 18 years old.
Men who take nitrates or guanylate cyclase stimulators.
Those with serious heart, liver, or low blood pressure conditions.
Individuals with known allergies to sildenafil* or other PDE5 inhibitors such as Tadalafil.2
Always consult your doctor before starting treatment, especially if you have other health concerns or medications.
Side Effects of Sildenafil
Sildenafil is generally well tolerated when used as directed. Possible side effects include:
Headache
Dizziness
Indigestion
Most side effects are mild and temporary. If symptoms persist or feel concerning, stop taking the medication and seek medical advice.
Medicines You Should Not Use with Sildenafil
Sildenafil may interact with certain medications. Avoid using it with:
Nitrate medications (commonly used for chest pain).3
Guanylate cyclase stimulators like riociguat.
Other ED treatments unless directed by your doctor.
Strong CYP3A4 inhibitors such as ketoconazole, ritonavir, or itraconazole.
Alpha-blockers or antihypertensives unless medically supervised.
Tell your doctor about all the medications or supplements you’re currently taking before starting sildenafil.
Frequently Asked Questions
The typical starting dose for most men is 50 mg taken before sexual activity. Depending on how your body responds, your doctor may adjust the dose to 25 mg or 100 mg. Never change your dose without medical guidance.
Sildenafil should be taken only once within a 24-hour period. It’s not meant for daily use; take it only when needed, about 30 minutes to 1 hour before sex.
Common side effects include headache, facial flushing, nasal congestion, and dizziness, indigestion. These effects are usually temporary and go away on their own.
At GoRocky, we're here to help men take charge of their health — confidently, discreetly, and without judgment.
We provide access to experts who can perform medical consultations that can assess for common issues like erectile dysfunction, while guiding you through real concerns about men's health.
Our goal? A world where men are healthier, happier, and more confident — starting with you. No stress, no shame, just straightforward care that works.
For more information, reach out at [email protected] or call +63 966 952 8623.
*The information provided on this platform is intended for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
[1] Sildenafil. MedlinePlus. Updated August 15, 2023. Accessed May 14, 2025.
[2] Who can and cannot take sildenafil. National Health Service. Updated March 2, 2022. Accessed May 14, 2025.
[3] 6 sildenafil (Viagra) interactions you should know about. GoodRx. Ulrich A. Updated June 3, 2024. Accessed May 14, 2025.