D., & Wicker, P. A. Oral sildenafil in the treatment of erectile dysfunction. The New England Journal of Medicine, 338(20), 1397–1404. A prospective study of the beneficial effects of dose optimization and customized instructions on patient satisfaction with sildenafil citrate (Viagra) for erectile dysfunction.

Country or Region	Prescription Requirement	Regulation Notes
United States	Prescription required	FDA approved for ED and PAH
European Union	Prescription required	Varies by country
Australia	Prescription required	Classified as prescription medicine

International Journal of Impotence Research, 18(5), 389–394. Sublingual sildenafil in the treatment of erectile dysfunction: Faster onset of action with less dose.

More about sildenafil

Most studies focus on 25-100mg dosages, but if your doctor thinks a lower dosage is the best option for you based on your medical profile, there is still a chance you can get the results you want. The maximum FDA approved dosage for sildenafil is 100mg per day. Studies show that moving from 25mg to 50mg and then to 100mg doses produces better results and that going above that threshold has no benefit and only increases the risk of side effects. Tadalafil and sildenafil come in different doses, and this is because the different dosages have different results. Sildenafil is available in 25, 50, and 100 mg doses because it is taken as needed and generally lasts 4-6 hours.

Sildenafil Tablets or Oral Suspension for PAH

Tadalafil comes in 2.5mg and 5mg versions for daily use, and 10mg and 20mg doses for taking as needed. The daily use doses (2.5mg and 5mg) should be taken daily in the morning, or at bedtime, while the as needed doses (10mg and 20mg) are generally taken about 30-60 minutes before sexual activity. Tadalafil is often referred to as “the weekend pill” as when taken even as needed,, will be effective for up to 36 hours. For best results men should take sildenafil 30-60 minutes before sexual activity. However it can be effective when taken up to 4 hours before, but its effectiveness peaks at about an hour after use. International Journal of Urology, 11(11), 989–993.

Sildenafil citrate works by blocking PDE5 enzymes.
It is not an aphrodisiac; arousal is necessary for effectiveness.
Consult a doctor before use, especially if on other medications.
Common side effects include headaches, flushing, and dizziness.

Sex, erectile dysfunction, and the heart: A growing problem.

Parameter	Value	Notes
Onset of Action	30-60 minutes	Typically reaches peak plasma levels in this time
Duration	Up to 4-6 hours	Effects can last for several hours
Bioavailability	~40%	Oral bioavailability varies with food intake
Half-life	3-5 hours	Half-life determines how long the drug stays active

Phosphodiesterase‑5 (PDE5) inhibitors in the management of erectile dysfunction. Pharmacy and Therapeutics, 38(7), 407–419.

Product	Dosage	Quantity + Bonus	Price
Viagra Generic	100mg	30 + 4 Pills	60.91€ 58.01€
Viagra Generic	50mg	360 + 10 Pills	225.33€ 214.60€
Viagra Generic	100mg	60 + 4 Pills	96.36€ 91.77€
Viagra Super Active	100mg	360 + 30 Pills	470.93€ 448.50€
Viagra Professional	100mg	270 + 6 Pills	456.97€ 435.21€
Viagra Professional	100mg	90 + 2 Pills	207.09€ 197.23€
Viagra Soft Tabs	100mg	10 Pills	36.93€ 35.17€
Viagra Super Active	100mg	120 + 16 Pills	198.37€ 188.92€
Viagra Generic	25mg	30 + 4 Pills	47.97€ 45.69€
Viagra Generic	200mg	360 + 10 Pills	481.98€ 459.03€
Viagra Generic	25mg	90 + 6 Pills	105.03€ 100.03€

Cardiovascular effects of sildenafil citrate and recommendations for its use.

What to avoid

If your erections are weak or inconsistent, then speak to your doctor about possibly increasing the dose. If you experience any headaches, vision problems, dizziness, or low blood pressure, then you may need to lower your dosage. Erections that last more than 4 hours is known as priapism, and is a serious medical condition for which you should seek immediate medical attention including visiting an emergency or urgent care facility. Your doctor should monitor how you react to your initially prescribed dosage. If the the starting dosage for example is 50mg, and is effective, no changes are necessary.

Key takeaways

However, keep track of any notable differences or side effects that might occur, just in case. One study concluded that through counselling and dose customization, many men found improved satisfaction rates when being treated for the first time with PDE-5 inhibitors such as sildenafil. 25mg is not a normally the initially prescribed dosage of sildenafil, but if your doctor prescribes the low dose for any reason, achieving an erection is still possible. Doctors have found during a study that at an even lower dosage of 20mg sildenafil taken under the tongue (sublingual), 65% of men were able to have satisfactory results. (7) However, the efficacy of sildenafil generally increases with dosage, with 82% of men having great results at 100mg. American Journal of Cardiology, 84(5), 11N–17N.

Sildenafil citrate can sometimes cause visual disturbances, such as blue-tinted vision.
Use the drug cautiously if you have eye disorders like retinitis pigmentosa.
Do not exceed the prescribed dose to prevent adverse effects.
In case of overdose, seek emergency medical help immediately.

Sildenafil is commonly used for the following conditions.

Generic Viagra is usually less expensive than brand-name versions.
Follow prescribed doses; do not double doses if one is missed.
It does not increase libido but boosts the ability to achieve an erection.
Use only as directed by a healthcare provider.

Erectile dysfunction, a condition where you have trouble getting or keeping an erection Pulmonary arterial hypertension, a condition where you have high blood pressure in the blood vessels that carry blood from your heart to your lungs Sildenafil may also be used for other conditions as determined by your healthcare provider. Sildenafil works by blocking an enzyme in the body called PDE5, which helps relax certain blood vessels.

Detection in biological fluids

Unlike tadalafil, there is no FDA‑approved daily sildenafil regimen. Taking it more than once in 24 hours can increase the risk of side effects and should be avoided unless prescribed by your doctor to be used that way. Exceeding the maximum dosage for sildenafil (more than 100 mg in 24 hours) does not improve erections and raises the risk of severe headaches, dizziness, low blood pressure, vision changes, and priapism (a prolonged erection requiring emergency care). Seek medical attention if you exceed the recommended daily maximum of 100mg in one day. Both doses work by improving blood flow, but the sildenafil 100 mg dosage is usually prescribed if 50 mg is not effective.

Viagra and herbs and supplements

Studies show a higher response rate at 100 mg, but also a greater chance of side effects. Doctors typically start at 50 mg and only viagra over the counter increase to 100 mg if needed. Physician-Scientist; Founder, Director, and Chief Executive OfficerXYON: Founder, Director, and CEOEducationDoctorate of Medicine (MD) — University of Cape Town, South Africa — 1991Genetics (PhD) — University of Amsterdam, The Netherlands — 1998Internal Medicine (Postgraduate Fellowship) — University of British Columbia (UBC), Canada — 2001Academic & Clinical AppointmentsClinical Assistant Professor, Division of General Internal Medicine — University of British ColumbiaAssociate Member, Division of Cardiology, Department of Medicine — University of British ColumbiaFaculty — Providence Health Care Heart and Lung Institute B., Ströberg, P., Lee, S. W., Park, N. C., Kim, S.-W., Tseng, L.-J., Collins, S., & Stecher, V. For erectile dysfunction, it increases blood flow to the penis when aroused.

Related/similar drugs

J. Sildenafil citrate 100 mg starting dose in men with erectile dysfunction in an international, double-blind, placebo-controlled study: Effect on the sexual experience and reducing feelings of anxiety about the next intercourse attempt. The Journal of Sexual Medicine, 6(10), 2826–2835. Sildenafil: A review of its use in erectile dysfunction. Effects of two different dosages of sildenafil on patients with erectile dysfunction. This makes it easier to get and keep an erection. For pulmonary arterial hypertension, sildenafil relaxes the blood vessels in the lungs.

Comparing Side Effects

American Journal of Men’s Health, 11(3), 747–757. Urologist recommends daily Viagra to prevent impotence. Goldstein, I., Lue, T. F., Padma-Nathan, H., Rosen, R. C., Steers, W. This lowers blood pressure and reduces strain on the heart.

Which Makes You Harder?

(11) Any man taking sildenafil for erectile dysfunction should be aware that drug interactions are one of the more important factors when deciding on whether the medication can be used safely and what dosage is safe. Nitrates can cause issues with blood pressure, alpha blockers can increase the risk of dizziness, CYP3A4 inhibitors such as ketoconazole, erythromycin, or ritonavir can slow the breakdown of the certain medications such as sildenafil in the blood and in these situations, your doctor will discuss whether sildenafil is safe and if so, what the safe dose and administration routine (eg daily or every second day) are. Grapefruit juice is a mild inhibitor of an enzyme known as CYP3A4 and can increase the risk of side effects with sildenafil as this medication is metabolized by CYP3A4 Whether you’re taking 25mg or 100mg, always tell your doctor about any other medications you’re taking, even if they’re over the counter. There is no perfect dosage of sildenafil for every man. 50mg is the most prescribed dose, but depending on the factors discussed in this article there may be a better dose for you based on your specific medical background and needs.FYI: Erectile dysfunction can be a side effect of common hair loss medications like finasteride.

Raynaud's phenomenon

If you're also struggling with hair loss and are worried about how treatment could affect performance, you may want to consider topical finasteride. For most healthy adults, the recommended starting sildenafil dosage is 50 mg taken about 30–60 minutes before sexual activity. Depending on your response and side effects, a doctor may adjust your sildenafil citrate dosage down to 25 mg or up to 100 mg Standard tablets for erectile dysfunction are 25 mg, 50 mg, and 100 mg. A sildenafil 20 mg dosage is primarily manufactured for pulmonary hypertension (Revatio). While 20 mg may help some men—especially in sublingual forms—many patients need higher doses for consistent results Sildenafil is generally intended for on‑demand use, not as a sildenafil daily dosage. 10 mg/mL powder for oral suspension 20 mg, 25 mg, 50 mg, 100 mg oral tablets Sildenafil is also available in an injectable form that is usually given by a healthcare provider in a hospital or clinic.

How should I take sildenafil?

To maximize the effectiveness of the medication, it’s best to take it on an empty stomach. A high fat meal can delay absorption by up to an hour and reduce the peak concentration of the medication by almost 30%. There are many factors that your doctor will evaluate when deciding on your ideal sildenafil dosage. Your age is an important factor and men over 65 for example, will likely start at a 25mg dosage before testing 50mg. Weight is generally not a direct factor in how well sildenafil will work, but low fitness levels or more severe ED may require patients to try a higher dose.

Is there a “female Viagra”?

Anyone with liver or kidney issues will also likely be started at the lower 25mg dose. You should discuss starting dose with your doctor as various factors may play into the choice of dosage. If you have stable heart disease, you can generally still take sildenafil, but your blood pressure should be monitored and in some cases, an exercise stress test might be administered prior to starting sildenafil. Men with significant coronary artery disease or with valvular narrowing's in the heart caused by aortic valve stenosis or hypertrophic obstructive cardiomyopathy (or HOCM) should not use sildenafil. In some cases men with eye problems such as retinitis pigmentosa, extra caution should be taken since the drug can have visual side effects.