Serious Risks and Contraindications

Breastfeeding Women: There is a lack of information about the effects of sildenafil on milk production and the effects of sildenafil on breastfed infants.

Side Effects

Sildenafil is a medication used in the management and treatment of erectile dysfunction and pulmonary arterial hypertension. It is in the phosphodiesterase-5 inhibitor (PDE5-I) class of medications. This activity describes the indications, actions, adverse effects, and contraindications of sildenafil as an agent in the clinical setting. Knowledge therein is critical for appropriate healthcare team management of patients with erectile dysfunction, pulmonary arterial hypertension, and/or related conditions. Explain the mechanism of action of sildenafil in the treatment of erectile dysfunction and pulmonary arterial hypertension.

What happens with ED?

Describe the clinically sildenafil citrate tablets 150 mg important drug interactions of sildenafil. Outline appropriate monitoring of sildenafil therapy in erectile dysfunction and pulmonary arterial hypertension. Summarize the role of the interprofessional healthcare team in improving care coordination and communication to improve outcomes related to sildenafil therapy. Sildenafil was the first phosphodiesterase-5 (PDE5) inhibitor approved for use, receiving US Food and Drug Administration approval for use in erectile dysfunction (ED) on March 27, 1998. [1] It also has US Food and Drug Administration (FDA) approval for the treatment of World Health Organization (WHO) Group I pulmonary hypertension (also known as pulmonary arterial hypertension [PAH]) in adults to improve exercise tolerance and delay clinical worsening. Sildenafil has systemic vasodilatory effects and, as such, should be prescribed with caution to patients who may be sensitive to such blood pressure changes, such as patients with left ventricular outflow obstruction and impaired autonomic control of blood pressure.

Country	Approval Status	Regulatory Agency	Notes
USA	Approved	FDA	For ED and pulmonary hypertension
European Union	Approved	EMA	Similar indications
India	Approved	CDSCO	Generic versions available
Australia	Approved	TGA	Prescription required

[14] Caution is needed when combining sildenafil with alpha-adrenergic blocking drugs and other antihypertensive agents.

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The use of sildenafil can infrequently result in a prolonged erection lasting more than 4 hours, also known as priapism, which, if left untreated, may result in damage to the penile tissue.

What should I do if I forget a dose?

[2] Sildenafil-induced delay in clinical worsening is demonstrated when sildenafil was used concomitantly with epoprostenol therapy. Clinical trials have established effectiveness for short-term use (12-16 weeks) and included patients, mainly patients with New York Heart Association (NYHA) Functional Class II-III symptoms and having idiopathic etiology or connective tissue disease (CTD). However, the addition of sildenafil to bosentan therapy did not result in any improvement in exercise capacity. Sildenafil is also occasionally used off-label for the treatment of: The molecular structure of sildenafil mimics that of cyclic guanosine monophosphate (cGMP). This similarity protects cGMP from degradation because sildenafil can bind to the catalytic site to act as a competitive inhibitor of cGMP-specific PDE5.

Missed Dose Instructions

This enzyme normally catalyzes the breakdown of vasodilatory cGMP. When PDE5 is active, cGMP is degraded, causing the vascular smooth muscle contraction, thereby limiting blood flow. [7] When PDE5 becomes inhibited, the accumulation of cGMP leads to increased cGMP-dependent protein kinase activity, which phosphorylates multiple targets in the smooth muscle cell. The result of smooth muscle cell target protein phosphorylation is a decrease in intracellular calcium, increased efflux of potassium, and deactivation of myosin light chain kinase, ultimately causing smooth muscle relaxation. Relaxation of vascular smooth muscle in the corpus cavernosum leads to penile erection when the cavernosal sinusoids engorge with blood to compress the subtunical veins against the tunica albuginea. Furthermore, sildenafil use requires caution in patients with anatomical deformation of the penis and patients with conditions potentially predisposing them to priapism, such as sickle cell anemia or multiple myeloma.

Side Effect	Severity	Common Symptoms	Frequency
Headache	Mild to Moderate	Throbbing pain, sensation of pressure	Very common
Flushing	Mild	Skin redness, warmth	Common
Dyspepsia (Indigestion)	Mild	Burning sensation in stomach	Common
Visual disturbances	Mild to moderate	Blue tint, blurred vision	Less common
Priapism	Severe	Prolonged and painful erection	Rare

Therefore, patients with a previous history of NAION or with a "crowded" optic disk should be prescribed sildenafil with caution.

Frequently asked questions

"Efficacy and safety of sildenafil citrate in women with sexual dysfunction associated with female sexual arousal disorder". "Vaginal sildenafil (Viagra): a preliminary report of a novel method to improve uterine artery blood flow and endometrial development in patients undergoing IVF". "Comparison of efficacy of sildenafil-only, sildenafil plus topical EMLA cream, and topical EMLA-cream-only in treatment of premature ejaculation". "Assessment of as needed use of pharmacotherapy and the pause-squeeze technique in premature ejaculation". "Efficacy of sildenafil citrate (Viagra) in men with premature ejaculation".

Are you currently using Sildenafil (Viagra, Revatio)?

"Sildenafil ameliorates effects of inhaled nitric oxide withdrawal". This book is distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) ( ), which permits others to distribute the work, provided that the article is not altered or used commercially. You are not required to obtain permission to distribute this article, provided that you credit the author and journal. A service of the National Library of Medicine, National Institutes of Health. Treasure Island (FL): StatPearls Publishing; 2026 Jan-. Sildenafil metabolism is catalyzed primarily by CYP3A4 and, to a lesser extent, by CYP2C9; thus, strong inhibitors of these isoenzymes may lead to the accumulation of sildenafil with subsequent toxicity.

How Sildenafil Works

Food and Drug Administration Ltd. Ahmedabad, INDIA 382220 For BluePoint Laboratories Rev. Alcohol-Sildenafil interaction has not been established. Talk to your doctor about the effects of taking alcohol with this medication. The contents of this FDA label are provided by the National Library of Medicine.

Dosage for erectile dysfunction (ED)

"Effects of sildenafil on esophageal motility of patients with idiopathic achalasia". "Sildenafil citrate for SSRI-induced sexual side effects". "Sildenafil in the treatment of antipsychotic-induced erectile dysfunction: a randomized, double-blind, placebo-controlled, flexible-dose, two-way crossover trial". "Sildenafil (viagra) facilitates weaning of inhaled nitric oxide following placement of a biventricular-assist device". "Safety and efficacy of sildenafil citrate for the treatment of female sexual arousal disorder: a double-blind, placebo controlled study". [18][19] The coadministration of sildenafil and ritonavir increased plasma sildenafil concentration (11-fold increase in the area under the curve due to CYP3A4/2C9 inhibition.

• Sildenafil is not recommended for children or minors.
• Elderly patients may need lower doses due to sensitivity.
• Use with caution if you have a history of stroke or unstable angina.
• Combining sildenafil with other ED drugs increases side effects risks.
• Be aware of counterfeit or substandard sildenafil products.
• Always purchase medication from reputable pharmacies.
• Consult a healthcare professional prior to initiating therapy.

Accordingly, caution is necessary for patients already on ritonavir when prescribing sildenafil.

• Some users report headaches and dizziness after taking sildenafil.
• A common side effect is facial flushing and nasal congestion.
• Rare side effects include sudden hearing loss or vision loss.
• Priapism requires urgent medical attention to prevent tissue damage.
• Sudden vision loss should be immediately evaluated by a doctor.
• Allergic reactions such as rash, hives, or swelling are possible.
• Discontinue use and seek medical help if serious side effects occur.

The recommendation is not to exceed a dose of 25 mg of sildenafil in 48 hours if taking ritonavir.

• Sildenafil shortens the time to achieve an erection.
• It does not cause spontaneous erections without sexual stimulation.
• Overdose signs include vision changes, persistent erections, or hypotension.
• It is linked to priapism, a sustained and painful erection.
• Always consult a healthcare provider before starting sildenafil.
• Store medication in a cool, dry place away from children.
• Combining with recreational drugs can cause dangerous interactions.

[7] Combining sildenafil with the endothelin antagonist bosentan to manage pulmonary arterial hypertension has correlated with increased serum concentrations of bosentan and reduced levels of sildenafil.

Continuing Education Activity

In patients with vasoactive pulmonary arterial hypertension, vasodilation of the pulmonary artery leads to reduced resistance to blood flow, with subsequent reductions in mean pulmonary arterial pressure. Sildenafil is available as oral tablets of 25 mg, 50 mg, and 100 mg strength for ED. Most patients receive a prescription for 50 mg of oral sildenafil, taken as needed approximately 1 hour before sexual activity. [7] The dose can be titrated upward to a maximum of 100 mg or down to 25 mg based on individual effectiveness and tolerance. Patients are advised not to exceed a maximum dosing frequency of once daily.

Dosage Modifications

It can be taken 30 minutes to 4 hours before desired intercourse. The onset of action can occur within 30 minutes, while the duration of the effect can last up to 18 hours. Consider starting at a dose of 25 mg in patients with hepatic dysfunction (eg, cirrhosis), patients with creatinine clearance (CLcr) less than 30 mL/minute (severe renal impairment), and patients age 65 years and above, as the administration of sildenafil in these group patients have resulted in higher plasma levels of sildenafil. Patients taking concomitant inhibitors of CYP3A4 may benefit from initiation at the lower dosage. In the treatment sildenafil otc of PAH, sildenafil is available in 20 mg tablets, oral suspension 10 mg/mL, and injectable 10 mg/12.5 mL forms. [19] Combining sildenafil with other CYP3A4 inducers can similarly lead to reduced sildenafil levels; thus, such combinations are not recommended with chronic sildenafil dosing as performed in managing PAH.

• Sildenafil binds to phosphodiesterase type 5 enzymes in tissues.
• It was initially developed by Pfizer.
• The drug’s patent expired in many countries, increasing generic availability.
• It can improve quality of life for men with ED and pulmonary hypertension.
• Discuss potential interactions and health conditions with your doctor.
• Usage guidelines differ for ED and pulmonary hypertension treatment.
• Follow the prescribed dose and avoid exceeding recommended limits.

Sildenafil, at its lowest dose, is recommended when initiating therapy in patients who are on alpha-blockers due to potential systemic hypotension.

What side effects can this medication cause?

The recommended dosage for tablet and oral suspension formularies is 5 mg or 20 mg three times daily, 4 to 6 hours apart. Injections are dosed at 2.5 mg or 10 mg three times a day, 4 to 6 hours apart, as an intravenous bolus. [11][12] Sildenafil injection is only indicated for the continued treatment of PAH when patients are currently on prescribed oral sildenafil treatment and are temporarily unable to take medicine orally. No dose adjustment is required in patients with renal impairment (including severe impairment CLcr <30 mL/min). No dose adjustment is required for mild to moderate hepatic impairment.

Does Viagra help with premature ejaculation?

Its use is not studied in patients with severe hepatic impairment. Pediatric Patients: Increased mortality with increasing sildenafil dose was observed in a clinical trial of pediatric patients with PAH. Deaths were first reported after approximately 1 year of use, and hence, sildenafil, particularly chronic use, is not recommended in pediatric patients with PAH. Pregnant Women: There are increased risks for stroke, heart failure, preterm delivery, and maternal and fetal death for pregnant women with untreated pulmonary arterial hypertension. Small case studies in pregnant women with PAH indicate a low risk of harm, though caution is warranted. Caution is also a requirement in patients taking mixed alpha/beta-blockers unless there is specific information regarding coadministration.

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