Sildenafil is a phosphodiesterase type 5 inhibitor that is prescribed to treat pulmonary arterial hypertension (PAH) in adults. Sildenafil helps improve one's ability to exercise if one suffers from PAH.







20 mg



I. Introduction

The emergence and evolution of Sildenafil represent a breakthrough in sexual well-being. Originally designed to address chest pain related to heart conditions, it was unexpectedly found to impact achieving and maintaining penile erections. The United States Food and Drug Administration approved Sildenafil, widely recognized as Viagra, in 1998 as the pioneer solution for treating erectile dysfunction.

History and Development of Sildenafil

Originally created by Pfizer researchers, Sildenafil was initially designed to address angina pectoris and hypertension by easing the tension in blood vessels. However, its clinical trials revealed promise in treating erectile dysfunction.

FDA Approval and Indications

Sildenafil was approved by the FDA in 1998. It is primarily used for treating Erectile Dysfunction and Pulmonary Arterial Hypertension under the brand name Revatio.

Overview of Mechanism of Action

Sildenafil functions by inhibiting a specific enzyme called phosphodiesterase type 5 (PDE5), which enhances the body's natural response to sexual arousal. This is achieved by promoting blood flow to the penis.

II. Uses of Sildenafil

Erectile Dysfunction

Sildenafil is a drug that belongs to a class of medications called phosphodiesterase type 5 inhibitors. It works by relaxing the muscles and increasing the blood flow to the penis, which helps men achieve and maintain an erection suitable for sexual intercourse. Sildenafil is a recognized and effective treatment for erectile dysfunction, affecting millions of men worldwide. Sildenafil can be taken on an empty stomach or with food, but it may take longer to work if taken with a high-fat meal or alcohol. Sildenafil can also have side effects like headache, flushing, indigestion, nasal congestion, and vision changes.

Here are some references:

Sildenafil: MedlinePlus Drug Information About sildenafil (Viagra) - NHS Sildenafil: Usage, Dosage & Side Effects - Erectile dysfunction: Viagra and other oral medications Benefits of Taking Viagra Daily - Healthline

Pulmonary Arterial Hypertension

Sildenafil is a drug that can be used to treat pulmonary arterial hypertension (PAH), a rare but severe condition that affects the blood vessels in the lungs. PAH causes high blood pressure in the lungs, which makes it harder for the heart to pump blood to the lungs and the rest of the body. Sildenafil works by relaxing the blood vessels in the lungs, which lowers blood pressure and improves blood flow. Sildenafil can also improve the exercise capacity and quality of life of people with PAH. Sildenafil is sold under the brand name Revatio for PAH and under the brand name Viagra for erectile dysfunction. Sildenafil can have side effects, such as headache, flushing, nausea, dizziness, and vision changes.

Here are some references:

FDA Drug Safety Communication: FDA clarifies Warning about Pediatric Use of Revatio (sildenafil) for Pulmonary Arterial Hypertension Sildenafil (for pulmonary arterial hypertension) - Ministère de la Santé et des Services sociaux Sildenafil (Revatio): Uses, Side Effects, Dosage & Reviews - GoodRx Revatio: Uses, Dosage & Side Effects - Sildenafil for pulmonary arterial hypertension Revatio - Sildenafil Tablets for Pulmonary Hypertension | Cleveland Clinic

Raynaud's Phenomenon

Sildenafil is a drug that can be used to treat Raynaud’s phenomenon, which causes the blood vessels in the fingers and toes to narrow and spasm in response to cold or stress. Raynaud’s phenomenon can cause pain, numbness, color changes, and sometimes ulcers or gangrene in the affected areas. Sildenafil works by relaxing the blood vessels and increasing the blood flow to the fingers and toes, reducing the frequency and duration of Raynaud’s attacks and improving the healing of ulcers. The FDA disapproves Sildenafil for Raynaud’s phenomenon, but doctors can prescribe it off-label. Sildenafil can have side effects, such as headache, flushing, indigestion, nasal congestion, and vision changes.

Here are some references:

Treatment of Raynaud phenomenon: Initial management - UpToDate Sildenafil in the Treatment of Raynaud’s Phenomenon Resistant to Vasodilatory Therapy - Circulation Full evidence summary | Digital ulcers: sildenafil | Advice | NICE

III. Off-label Uses of Sildenafil

Altitude Sickness

Sildenafil is a drug that can be used to prevent or treat high-altitude hypoxic pulmonary hypertension. This condition occurs when the blood vessels in the lungs constrict and increase the pressure in the pulmonary artery at high altitudes. High altitude hypoxic pulmonary hypertension can cause shortness of breath, chest pain, fatigue, and impaired exercise performance. Sildenafil works by relaxing the blood vessels in the lungs, which lowers the pressure in the pulmonary artery and improves oxygen exchange. Sildenafil can also improve the symptoms and quality of life of people with high-altitude hypoxic pulmonary hypertension. The FDA disapproves Sildenafil for high-altitude hypoxic pulmonary hypertension, but doctors can prescribe it off-label. Sildenafil can have side effects, such as headache, flushing, indigestion, nasal congestion, and vision changes.

Here are some references:

Acute Altitude Illness: Updated Prevention and Treatment Guidelines - American Family Physician Sildenafil citrate for the prevention of high altitude hypoxic pulmonary hypertension: double blind, randomized, placebo-controlled trial - Europe PMC Sildenafil does not improve performance in 16.1 km cycle time trial at moderate simulated altitude - PLOS ONE

Heart Failure

Recent studies indicate that Sildenafil could offer advantages to individuals with heart failure by easing the tension in blood vessels and enhancing blood circulation to the heart tissue123.

1Viagra and Cialis for heart failure? - Harvard Health 2Effects of Viagra on Heart Function in Patients With Heart Failure … 3New Data Indicates That Viagra May Protect Against Heart Disease - Forbes

Antidepressant-Associated Sexual Dysfunction

For people who are facing sexual side effects caused by antidepressant medications, Sildenafil has been studied as a solution to alleviate these effects, and it has often shown significant success123.

1Managing Antidepressant-Induced Sexual Dysfunction: A Holistic Approach 2How to Reduce Sexual Side Effects From Antidepressants - Verywell Mind 3Managing Antidepressant Sexual Side Effects - Healthline

IV. How Sildenafil Works


Sildenafil, a specific inhibitor of PDE5, boosts the levels of cGMP. As a result, it enables the muscles to relax smoothly and promotes improved blood circulation.


The body quickly takes up sildenafil, and peak levels in the bloodstream are typically achieved within an hour after taking it. Around 40% of the drug can be effectively utilized by the body, while the liver breaks down during metabolism.

Impact on Nitric Oxide and cGMP Pathway

Sildenafil works by preventing the breakdown of cGMP, which helps to increase the effects of nitric oxide. Nitric oxide is a chemical that relaxes the muscles in the penis and improves blood flow making it easier to achieve erections when sexually stimulated.

V. Dosage and Administration

To treat Erectile Dysfunction, the recommended dose is usually 50 mg. It can vary between 25 mg and 100 mg depending on individual needs. On the hand for Pulmonary Arterial Hypertension, it is generally advised to take 20 mg three times, per day.

Titration and Adjustment of Dosage

Doctors can adjust the dosage of Sildenafil depending on how effective it's and how well it is tolerated ensuring that any adjustments are made carefully to minimize the risk of side effects.

Route of Administration

Sildenafil is taken by mouth. Can be found in the form of tablets or as a liquid suspension you swallow.

VI. Composition of Sildenafil

Active Ingredients

The main component found in Sildenafil is known as sildenafil citrate.

Inactive Ingredients and Excipients

Standard inactive components often found in medications consist of microcrystalline cellulose anhydrous dibasic calcium phosphate and magnesium stearate, among others.

Available Forms (Tablets, Liquid)

You can find Sildenafil in the form of tablets or as a liquid suspension that you take by mouth.

VII. Side Effects of Sildenafil

Common Side Effects

  • Headache
  • Flushing
  • Dyspepsia
  • Nasal congestion

Serious and Rare Side Effects

Sometimes although it is uncommon, there can be adverse effects such as loss of vision or hearing and a prolonged erection lasting more, than 4 hours (known as priapism), which necessitates immediate medical attention.

Managing Side Effects

Patients should consult their healthcare provider regarding any side effects. Adjusting the dosage switching to an alternative medication, or implementing supportive measures can be effective approaches, for managing side effects.

VIII. Interactions

Drug-Drug Interactions

Sildenafil has the potential to interact with medications, which may result in changes to their effects or an increased risk of unwanted reactions. Notable interactions include; Nitrates, commonly prescribed for chest pain can cause a risky decrease in blood pressure. Alpha-blockers are used for treating prostate conditions and hypertension. Protease inhibitors employed in HIV treatment. Certain antifungal and antibiotic medications. It is crucial to be aware of these interactions when taking sildenafil alongside drugs.

Food and Alcohol Interactions

Drinking alcohol can worsen the side effects, including decreased blood pressure. Moreover, if you take Sildenafil with a meal that's high in fat, it might take longer for the medication to start working because it will be absorbed more slowly.

Herbal and Supplement Interactions

It is essential to be cautious when using Sildenafil alongside products potentially impacting blood pressure, such as St. Johns Wort, Ginkgo biloba, and other similar substances. Additionally, supplements like L arginine may interact with Sildenafil due to their influence on nitric oxide pathways.

IX. Warnings and Precautions

Cardiovascular Risks

Patients who already have the disease might face increased risks when using Sildenafil. These individuals need to discuss with their healthcare provider regarding the potential advantages and disadvantages.

Vision and Hearing Risks

In a few cases, the use of Sildenafil has been linked to abrupt loss of vision and hearing. Patients must be aware of this and seek medical assistance if they experience these symptoms.

Hypotensive Risks

Sildenafil can potentially enhance the blood pressure-lowering effects of nitrates, resulting in a significant decrease in blood pressure. As a result, patients must be aware of this risk, particularly if they are currently taking medications.

X. Contraindications

Absolute Contraindications

If you have a known allergy to Sildenafil or any ingredient in this medication, it is important not to take it. Additionally, if you currently use nitrates in any form, it is not recommended as it may lead to a drop in blood pressure.

Relative Contraindications

Patients with pre-existing conditions, like severe cardiovascular disease or significant hepatic impairment, should exercise great caution and only use Sildenafil under the close supervision of a medical professional.

Contraindicated Medications

It is not recommended to use this medication in combination with nitrates, riociguat, or specific antifungal or antibacterial drugs due to the possibility of negative interactions.

XI. Careful Administration and Monitoring

Monitoring Parameters

It's crucial to maintain check-ins with a healthcare provider. They will monitor factors like blood pressure, how well the treatment is working, and any possible side effects.

Initial and Ongoing Assessments

Before starting treatment with Sildenafil, it is essential to conduct a medical history review and physical examination. Regularly evaluating the response to the medication and reassessing the need for treatment are crucial aspects of patient care.

Special Populations Considerations

Some groups of people, like those with kidney or liver problems, might need to adjust the dosage and have monitoring to reduce any potential risks that could arise from using Sildenafil.

XII. Administration to Special Populations

Administration to Elderly Patients

Although elderly patients typically tolerate Sildenafil well, they may experience heightened sensitivity to its effects. To prevent any worsening of age-related health conditions, it is recommended to carefully select the dosage at the lower end of the range.

Administration to Pregnant Women and Nursing Mothers

Sildenafil is not recommended for women. If you are pregnant or breastfeeding, it's important to have a discussion with your healthcare provider about any potential risks involved.

Administration to Children

Sildenafil has received approval from the FDA for treating Pulmonary Arterial Hypertension in children. However, it is crucial to have a healthcare professional with expertise in hypertension carefully guide its usage for this purpose.

XIII. Overdosage

Signs and Symptoms of Overdose

When there is an intake of Sildenafil, individuals might encounter symptoms that are essentially a continuation of its recognized side effects. These symptoms encompass hypotension (significantly low blood pressure), impaired vision or sudden loss of vision, prolonged and painful erection (priapism), and sudden hearing loss or ringing in the ears.

Management and Treatment of Overdose

The treatment for an overdose of Sildenafil mainly involves providing care since no specific antidote is available. The options for managing this situation include seeking medical attention to evaluate and stabilize the patient's condition administering fluids to address dehydration and maintain blood pressure, closely monitoring vital signs, and implementing necessary interventions.

Contacting Poison Control

If you suspect an overdose, it is essential to reach out to a poison control center as a measure. They will be able to offer advice and guidance that is specific, to the situation you are facing.

XIV. Storage Requirements for Sildenafil

Ideal Storage Conditions

Sildenafil must be kept where the temperature's comfortable, neither too hot nor too cold. The recommended conditions for storage are as follows; Temperature; between 20 and 25°C (68 to 77°F). Avoid exposing it to heat or frigid temperatures.

Shelf Life

Similar to medications, Sildenafil has a specific expiration date. Patients need to check the expiry date on the packaging and avoid using the medication beyond that point, as its effectiveness may be compromised.

Disposal of Expired Medication

It's essential to dispose of expired or unused Sildenafil by following community pharmaceutical disposal programs. Avoid throwing medications in the household trash or flushing them down the toilet unless you have explicitly been instructed.

XV. Handling Precautions

Safe Handling and Dispensation

Sildenafil should only be taken by the person it was prescribed for. It is important not to share this medication with others, even if they have symptoms.

Protecting from Moisture and Light

Keep Sildenafil in its packaging, ensuring the container is tightly closed to shield the tablets from moisture and light.

Child Safety Precautions

It is essential to keep Sildenafil from children in a place they cannot easily reach to prevent accidental consumption.

XVI. Conclusion

Summary of Key Points

Initially intended for treating heart conditions, Sildenafil gained recognition for its ability to address erectile dysfunction and pulmonary arterial hypertension. It works by blocking an enzyme leading to the relaxation of blood vessels and improved circulation. However, it is crucial to note that this medication has risks of interactions, side effects, and contraindications. Therefore it is essential to have medical supervision when using it.

Current Research and Future Developments

Ongoing research is exploring the uses of Sildenafil. Studies are looking into its effectiveness in treating a wide range of conditions, including heart failure, neonatal pulmonary hypertension, and even aiding in stroke recovery.

Consult Healthcare Professional for Personalized Advice

Although this article explains Sildenafil, patients must seek guidance from a healthcare professional who can provide personalized advice based on their circumstances and health condition. Only a qualified healthcare professional has the expertise to offer recommendations taking into account the patient's complete medical history, current medications, and specific symptoms.

Rated: 5.0 / 5 based on 5.0 customer reviews.

Posted by Ladonna on Apr 12, 2017 Verified Purchase

Good Product

The product is good, but the delivery time is very slow and takes longer than it did a year or two ago. It typically takes three weeks. I guess there is not a lot you can do about that.

Note: does not imply any medical claims from this review.

Customers also bought

Popular Products

Similar Product