Sildenafil dosage: a guide to labeled dosing
Sildenafil dosage depends on the condition treated and your health risks. Here is what the FDA label says about dosing and timing.
Key facts
- Sildenafil is $69.67/month (billed $209 every 90 days), charged only after a clinician approves it.
- Answer a few health questions online. A licensed clinician reviews them. If approved, it ships to your door.
- Adults 18 or older. A licensed clinician reviews your health history and decides whether treatment is appropriate for you. Availability depends on the state you live in.
Sildenafil (generic Viagra) is prescribed at different doses depending on why you are taking it, your other medications, and your heart and blood pressure risks. This guide summarizes labeled dosing for erectile dysfunction (ED) and for pulmonary arterial hypertension (PAH) using FDA prescribing information. If you have questions about your own sildenafil dose, PocketMD from Vitals Vault can help you ask safer questions, but dose decisions still belong with your prescribing clinician.
- Sildenafil dosage is condition-specific and should follow the FDA label and your clinician’s instructions.
- For erectile dysfunction, sildenafil is taken as needed, not more than once daily, per the FDA label.
- For pulmonary arterial hypertension, sildenafil is dosed on a regular schedule, per the FDA label.
- Do not use sildenafil with nitrates, and avoid it with riociguat due to dangerous low blood pressure risk.
What is the labeled sildenafil dosage?
ED (as needed)
For erectile dysfunction, the FDA label describes sildenafil as an as-needed medicine taken before sexual activity, with a maximum recommended dosing frequency of once per day. Your clinician may adjust the dose based on effectiveness and tolerability.
PAH (scheduled)
For pulmonary arterial hypertension, sildenafil is taken on a regular schedule rather than as needed. The FDA label lists a specific dose and dosing frequency for this indication, and changes should be made by the prescribing clinician.
Not interchangeable
ED and PAH dosing are not interchangeable. The FDA label treats these as different indications with different dosing approaches, and your clinician chooses the regimen that matches your diagnosis and risk factors.
Dose details, timing, and key safety limits
| Indication | How it is taken | Label dosing notes | Important limits |
|---|---|---|---|
| Erectile dysfunction (ED) | Taken as needed before sexual activity | Dose is individualized; label describes a maximum dosing frequency of once daily | Do not use with nitrates; avoid with riociguat |
| Pulmonary arterial hypertension (PAH) | Taken on a regular schedule | Label provides a specific dose and frequency for PAH | Do not use with nitrates; avoid with riociguat |
Do not combine with nitrates
Sildenafil can dangerously lower blood pressure when combined with nitrates (for example, nitroglycerin). This is a labeled contraindication. If you have chest pain and have taken sildenafil, tell emergency clinicians so they can choose safer options.
Avoid riociguat
Sildenafil is contraindicated with riociguat, a medicine used for certain types of pulmonary hypertension. Using them together can cause significant low blood pressure.
Alpha-blockers and other blood pressure drugs
Sildenafil can add to the blood pressure lowering effects of alpha-blockers and antihypertensives. Your prescriber may adjust timing or dose and may advise you to watch for dizziness or fainting, especially when starting or changing therapy.
Strong CYP3A4 inhibitors
Some medicines can raise sildenafil levels by slowing its breakdown (metabolism), including certain antifungals, antibiotics, and HIV medicines. The FDA label includes dose adjustments or limits in specific situations, so your prescriber needs a full medication list.
Grapefruit products
Grapefruit can inhibit CYP3A4 and may increase sildenafil exposure. If you use grapefruit regularly, ask your clinician or pharmacist whether it matters for your regimen.
Common side effects
Common side effects in the label include headache, flushing, indigestion (dyspepsia), nasal congestion, and visual color tinge or blurred vision. If side effects are bothersome or persistent, your prescriber can reassess the plan.
When to talk to a clinician urgently
Chest pain or fainting
Get urgent medical care for chest pain, severe dizziness, fainting, or symptoms of very low blood pressure after taking sildenafil. Tell the care team you took sildenafil, especially before any nitrate treatment.
Erection lasting too long
Seek urgent care for an erection that lasts more than 4 hours (priapism). This is a medical emergency that can cause permanent damage if not treated quickly.
Sudden vision or hearing changes
Stop sexual activity and get medical evaluation for sudden vision loss, sudden decrease or loss of hearing, or ringing in the ears with dizziness. These events are rare but listed in warnings for PDE5 inhibitors like sildenafil.
New shortness of breath or swelling
If you are taking sildenafil for PAH and develop worsening shortness of breath, fainting, or swelling, contact your PAH clinician promptly. These can signal disease progression or another urgent issue.
Sildenafil dosing tips you can use
Share your full med list
Include nitrates, alpha-blockers, and HIV or antifungal medicines so dosing can be chosen safely.
Plan for food effects
For ED, high-fat meals can delay onset for sildenafil tablets, per the label.
Avoid alcohol overuse
Alcohol can worsen ED and increase dizziness from blood pressure lowering.
Track response, not inches
Sildenafil supports erections; it does not change penis size.
Ask about heart risk
ED can be an early sign of cardiovascular disease. A clinician can assess risk factors.
Frequently Asked Questions
How many inches does Viagra give you?
None. Sildenafil (Viagra) helps increase blood flow to support an erection when you are sexually stimulated, but it does not increase penis size. If you are not getting the response you expect, a clinician can review dose, timing, and other causes of ED.
How much Viagra should I take?
Only your prescriber can tell you your dose. The FDA label describes different dosing approaches for ED (as needed, not more than once daily) versus PAH (scheduled dosing), and your clinician chooses based on your health and medications.
What is the usual sildenafil dosage for erectile dysfunction?
The FDA label describes sildenafil for ED as an as-needed medicine taken before sexual activity, with a maximum recommended frequency of once per day. The specific dose is individualized based on effectiveness, side effects, and drug interactions.
Is sildenafil 45 mg a standard dose?
The FDA-labeled tablet strengths for sildenafil used for ED are 25 mg, 50 mg, and 100 mg. A 45 mg dose is not a standard labeled tablet strength, so if you see it on a plan, ask your prescriber to explain the formulation and instructions.
Can I take sildenafil every day?
For ED, the FDA label limits dosing frequency to no more than once daily, but whether daily use is appropriate depends on your health and other medicines. For PAH, sildenafil is taken on a scheduled regimen under specialist guidance.