Is sildenafil 20 mg enough?

Sildenafil, more commonly known by the brand name Viagra, is a medication used to treat erectile dysfunction (ED). It comes in various dosages, with 20 mg being on the lower end. Whether 20 mg of sildenafil is enough depends on several factors.

Quick answers:

– For many men, 20 mg of sildenafil is enough to help achieve and maintain an erection. However, some men may need a higher dosage.

– Effectiveness can depend on the individual’s age, weight, medical history, and severity of ED. Older men or men with more advanced ED may need a higher dose.

– 20 mg is the commonly recommended starting dose. If it is not sufficiently effective, the dosage can be increased to 40 mg or 60 mg.

– Taking a higher dose does not necessarily increase effectiveness but does increase the risk of side effects. The lowest effective dose should be used.

– Sildenafil may not work on the first try – it may take several attempts at a dosage to determine if it is working optimally.

– Other factors like timing of dose, food intake, and alcohol consumption can impact how well sildenafil works. Taking it on an empty stomach and avoiding alcohol improves absorption.

– For the 20 mg dose, onset of action is typically within 30-60 minutes and lasts for around 5 hours. A higher dose may act faster and last longer.

– Side effects like headaches, flushing, indigestion, nasal congestion are more common with higher doses. 20 mg is less likely to cause side effects.

– Sildenafil does not produce an automatic erection – sexual stimulation is still required for it to be effective.

How sildenafil works

Sildenafil belongs to a class of medications called PDE5 inhibitors. It works by inhibiting an enzyme called phosphodiesterase type 5, which normally breaks down a substance called cyclic guanosine monophosphate (cGMP). cGMP is produced when nitric oxide (NO) is released during sexual stimulation.

Without sildenafil With sildenafil
  • NO is released during sexual stimulation
  • NO stimulates production of cGMP
  • cGMP promotes relaxation of smooth muscle in the penis allowing blood flow
  • Phosphodiesterase 5 breaks down cGMP
  • Erection ends
  • NO is released during sexual stimulation
  • NO stimulates production of cGMP
  • Sildenafil inhibits phosphodiesterase 5 from breaking down cGMP
  • Increased levels of cGMP prolong smooth muscle relaxation
  • Improved blood flow results in an erection

By preventing the breakdown of cGMP, sildenafil allows for increased blood flow into the penis when a man is sexually stimulated. This helps men with ED achieve and maintain an erection.

Sildenafil does not have a direct effect on sexual stimulation itself. It is not an aphrodisiac and does not increase sexual desire. It only facilitates the erectile response to existing stimulation.

Onset and duration of action

When taken as needed with a dose of 20 mg, sildenafil becomes effective within 30 to 60 minutes. The effects last for approximately 5 hours.

A higher dose of sildenafil tends to act slightly faster and lasts longer. With 40 mg, onset is around 30 minutes and duration is about 6 hours. A dose of 60 mg may begin working in as little as 15 minutes and last for up to 8 hours.

However, there is a limit to how much more effective a higher dose will be. Beyond a certain point, increasing the dosage does not really result in a significantly longer or stronger effect.

It is best to start with a lower 20 mg dose first and only increase it if the desired response is not achieved. Taking more than necessary will just lead to more side effects.

Who should consider a higher dose?

While 20 mg sildenafil is likely sufficient for many patients with ED, some men may require a higher dose of 40-60 mg for optimal results. This includes:

Older men

Age can be a factor in how well sildenafil works. As men get older, erectile function tends to decrease.

The metabolism of sildenafil also slows down with age. This means older men need a higher dose to achieve the same level of response as younger men.

According to clinical data, men over 65 years of age did not see much improvement in ED symptoms with a 20 mg dose. But with 40-60 mg doses, older men had significantly better erectile function.

Men with more severe ED

Men who have severe or complete inability to achieve erections tend to need higher doses of sildenafil. With more advanced ED, the 20 mg dose may not provide sufficient increased blood flow to the penis.

In clinical studies, men with mild ED saw adequate improvement in erections with 20 mg sildenafil. But men with more moderate-to-severe ED required at least 40 mg for a significant beneficial effect.

Men with other medical conditions

Certain medical conditions can mean a higher dose is needed because the drug is cleared from the body more quickly. These include:

– Liver or kidney dysfunction – Impaired liver or kidney function can reduce how long sildenafil remains active in the body. A higher dose accounts for the faster clearance.

– Diabetes – Sildenafil is metabolized faster in people with type 1 and type 2 diabetes. 50-100 mg doses may be needed for adequate response.

– Spinal cord injury – Due to circulatory differences, the standard dose for ED in spinal cord injury patients is 50-100 mg.

– Prostate surgery – Men who have undergone complete prostate removal may need increased doses up to 100 mg.

Recreational use

While it is only FDA approved for ED, some individuals take sildenafil recreationally. Recreational use refers to taking it to enhance sexual experience, rather than for a medical purpose. The typical recreational dose is 50-100 mg, which is higher than the standard medical dose.

However, recreational use of sildenafil is not recommended. High doses increase the risks of side effects like dangerously low blood pressure, visual disturbances, and priapism (prolonged erection).

Trying a higher dose

The best way to determine if a higher dose of sildenafil is appropriate is through a consult with a doctor. They can evaluate if individual factors warrant increasing the dosage. However, here are some general tips on finding the optimal dosage:

– Start with 20 mg and only increase the dose if it does not provide the desired effect.

– Try taking 40 mg and assess the efficacy and side effects. Increase to 60 mg only if needed.

– Take the higher dose on an empty stomach for best absorption. Avoid heavy fatty meals and alcohol.

– Wait 1-2 hours after taking the higher dose to gauge the full effects before attempting intercourse.

– Do not take more than 100 mg in a 24 hour period. Consider chronic daily low doses instead of sporadic high doses.

– Monitor side effects carefully. If intolerable side effects occur on higher doses, go back to lower dose.

– Give each dose a few tries before deciding to increase the dosage further. Effectiveness may vary from day to day.

Benefits and risks of higher doses

Increasing sildenafil dosage has both potential benefits and risks:

Potential benefits

– May provide longer duration of action. 60 mg may work for up to 8 hours vs 5 hours with 20 mg.

– Generates a greater peak concentration, which may improve erectile response.

– Necessary for adequate efficacy in certain groups like elderly men and those with severe ED.

Potential risks

– Higher incidence of side effects like headaches, visual changes, flushed skin, nasal congestion, dyspepsia.

– Increased risk of more serious adverse effects like dangerously low blood pressure, loss of vision or hearing, and prolonged erections requiring medical treatment.

– Higher cost of medication at increased dosages.

– Taking more medication than needed effective treatment.

Alternative dosing approaches

For some patients who do not get optimal results from taking sildenafil on-demand at higher single doses, there are alternative dosing regimens to consider.

Split doses

Rather than taking the full dose at once, it can be split into multiple smaller doses taken over a few hours. For example:

– A 40 mg dose split into 20 mg taken twice, two hours apart

– A 60 mg dose split into three 20 mg doses spaced two hours between each dose

Splitting the higher dose avoids excessive peak concentrations, while extending its effectiveness.

Daily low dose

For frequent sexual activity, a low 5-10 mg dose can be taken daily. This builds up a constant low level of sildenafil rather than relying on a single higher dose when needed. It allows for more spontaneity in sexual activity.

Alternative medications

If sildenafil is not working well at maximally tolerated doses, other ED medications can be considered like:

– Tadalafil – Longer lasting, can be taken as a daily low dose
– Vardenafil – Similar profile to sildenafil
– Avanafil – Faster onset than sildenafil

However, these other drugs tend to be more expensive than sildenafil.


The recommended starting dose of sildenafil for ED is 20 mg taken as needed about 1 hour before sexual activity. However, some patients may require higher doses of 40-60 mg for adequate efficacy and duration of action.

Older men, those with more severe ED, and those with conditions affecting drug metabolism often need higher doses. But the dose should be increased cautiously to avoid excessive side effects.

Consider alternative dosing methods like split or daily low dose regimens if higher single doses do not provide sufficient effects or cause intolerable side effects.

Overall, 20 mg is an appropriate starting dose for most patients, but some individuals may benefit from tailored dose adjustments to identify the optimal dosage of sildenafil.

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