Sildenafil, a brand name for a formulation containing essential Sildenafil, is widely used for various health benefits. This guide provides comprehensive information on the uses, dosage, side effects, and mechanism of action of Sildenafil, as well as insights into how long it takes to work. Understanding these aspects can help you make informed decisions about its use and effectiveness.

Sildenafil Introduction

Sildenafil is an oral medication used to treat erectile dysfunction, pulmonary arterial hypertension (PAH), and benign prostatic hyperplasia (BPH). It belongs to a class of drugs known as phosphodiesterase type 5 (PDE5) inhibitors and works by increasing blood flow to the penis to help a man maintain an erection.


Sildenafil is primarily used to treat erectile dysfunction, it may also be used to treat PAH and BPH.

Mechanism of Action

Sildenafil works by inhibiting the enzyme Phosphodiesterase 5 (PDE5). Inhibition of PDE5 increases levels of cGMP in the smooth muscle cells, which increases the amount of blood that can flow to the penis, leading to an erection.

How Long Does It Take to Work?

Sildenafil typically begins to take effect within 30-60 minutes and can last up to 4 hours. It is important to note that an erection will not occur just by taking a pill; sexual stimulation is necessary.


Sildenafil is well absorbed following oral administration; maximum plasma levels generally reached within 1 hour.

Route of Elimination

Sildenafil is metabolized in the liver by cytochrome P450 3A4 (CYP3A4). It is then eliminated primarily by the kidneys.


  • Erectile Dysfunction: The recommended dose is 50mg taken as needed approximately 1 hour before sexual activity. Dose may be increased to 100 mg or decreased to 25 mg based on individual efficacy and tolerability.
  • PAH: The recommended dose is 20mg taken 3 times daily. Dose may be increased up to 100mg, based on individual efficacy and tolerability.
  • BPH: The recommended dose is 5mg taken once daily.


Sildenafil should be taken orally with a glass of water.

Side Effect

The most commonly reported side effects are headache, facial flushing, indigestion, nasal congestion, and dizziness.


Sildenafil has a low potential for toxicity. Overdoses of greater than 2000mg can be associated with severe adverse effects and should be managed with supportive care as needed.


Patients with heart conditions such as angina (chest pain) or cardiac arrhythmias should use with caution as it may increase the risk of heart attack or stroke. Patients with known hypersensitivity to Sildenafil or any of its components should not take the medication.


Sildenafil may interact with other medications such as nitrates, alpha blockers, antifungals, and azole antacids. It is important to speak to your doctor before taking sildenafil to ensure there are no potential drug interactions.

Disease Interaction

Sildenafil can interact with certain diseases such as liver or kidney disease, sickle-cell anemia, and priapism. It is important to discuss any existing health conditions with your doctor prior to taking sildenafil.

Drug Interactions

Sildenafil can interact with certain drugs such as aspirin, ibuprofen and blood thinners. It is important to talk to your doctor before taking sildenafil to ensure there are no potentially significant drug interactions.

Food Interactions

Sildenafil should be taken empty stomach or at least an hour before meals. It should not be taken with meals as it may reduce the effectiveness of the medication.

Pregnancy Use

Sildenafil should not be used by pregnant women due to the potential risks to the fetus.

Lactation Use

Sildenafil should not be used by nursing mothers due to the potential risk to the infant.

Acute Overdose

Patients who overdose should be managed with supportive care. Common symptoms of overdose include flushing, dizziness, nausea, and hypotension.


Sildenafil is contraindicated for patients with any kind of peptic ulcer, bleeding disorders, and hypersensitivity to any of the components of the medication.

Use Direction

Sildenafil should be taken as directed by your doctor. Do not take more or less than what is prescribed. Do not share your medication with others.

Storage Condition

Sildenafil should be stored away from heat, light, and moisture in a place that is inaccessible to children.

Volume of Distribution

The volume of distribution of sildenafil is approximately 105 L.

Half Life

The half life of sildenafil is 3-5 hours.


The clearance of sildenafil is approximately 41 L/hr.

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