What is Sildenafil?
Sildenafil citrate is a treatment for erectile dysfunction (ED), which means trouble getting or keeping an erection, and pulmonary arterial hypertension (PAH), which is high blood pressure in the arteries of the lungs.
For ED, sildenafil 25mg improves blood flow to the penis, making it easier to get and maintain an erection. For PAH, it relaxes the blood vessels in the lungs, which lowers the pressure and makes it easier for the heart to pump blood.
Sildenafil off-label use means it is sometimes prescribed for other conditions that are not officially approved.
These include:
- Secondary Raynaud phenomenon, where fingers and toes turn white or blue in response to cold or stress
- Female sexual arousal disorder, which is trouble with sexual excitement in women
- Altitude-induced hypoxemia is low oxygen levels in the blood at high altitudes. These uses work because sildenafil helps improve circulation and the delivery of oxygen in the body.
Indications and Benefits of Sildenafil
Sildenafil is a treatment for erectile dysfunction (ED) and pulmonary arterial hypertension (PAH). ED is when a man has difficulty getting or keeping an erection.
This improves circulation in specific areas of the body depending on the condition being treated.
What Are the Benefits of Sildenafil?
- Sildenafil improves blood flow to the penis, making it easier to get and keep an erection during sexual activity.
- It relaxes blood vessels in the lungs, lowering blood pressure in that area and helping the heart pump blood more effectively.
- By reducing the strain on the heart, sildenafil can help people with PAH move and exercise more comfortably.
- Sildenafil helps widen blood vessels, which can improve oxygen delivery and blood flow in the body.
- In some cases, healthcare providers may recommend sildenafil for secondary Raynaud phenomenon, female sexual arousal disorder, or altitude-induced hypoxemia, based on its blood vessel-relaxing effects.
How Sildenafil Works
Sildenafil works by helping blood vessels relax and dilate, thereby improving blood flow. It targets an enzyme in the body called PDE5, which normally causes blood vessels to constrict.
According to a study published in the National Library of Medicine, in erectile dysfunction, this improved blood flow goes to the penis, making it easier to get and keep an erection during sexual stimulation. In pulmonary arterial hypertension, the same process happens in the blood vessels of the lungs.
The blood vessels relax, lung pressure decreases, and the heart can pump blood more easily. This can help improve breathing and make physical activity less tiring.
Dosage
Sildenafil is available in various strengths, depending on the condition being treated. The right sildenafil dosage depends on factors such as age, overall health, and how well the body responds to the treatment.
What Dosage Strengths Does Sildenafil Come In?
- 25 mg tablets
- 50 mg tablets
- 100 mg tablets
- 20 mg tablets (for pulmonary arterial hypertension)
- 10 mg/mL oral suspension
- 2.5 mg or 10 mg injection
Dosage Chart
| Condition | Typical Starting Dose | Maximum Dose | How Often to Take | Special Considerations |
| Erectile Dysfunction (ED) | 50 mg about 1 hour before activity | 100 mg once daily | As needed, 30 min to 4 hrs before sexual activity | Start at 25 mg for adults over 65, with liver or kidney issues, or when taking certain other drugs |
| Pulmonary Arterial Hypertension (PAH) – Tablets/Suspension | 20 mg three times daily | Not applicable | Every 4 – 6 hours | No dose change for kidney issues; caution in severe liver disease |
| Pulmonary Arterial Hypertension (PAH) – Injection | 2.5 mg or 10 mg three times daily | Not applicable | Every 4 – 6 hours | Only when the patient cannot take sildenafil by mouth |
| Older Adults (65+) or Severe Kidney/Liver Problems | 25 mg | 100 mg once daily | As needed for ED | Higher sildenafil levels may occur; a lower dose helps reduce side effects |
Usage Guide
Sildenafil is taken by mouth in tablet, liquid, or injection form, depending on the condition being treated. The right way to take it depends on whether it is for erectile dysfunction or pulmonary arterial hypertension.
Following the correct sildenafil dosage and timing helps achieve the best results while reducing the risk of side effects.
How do you take Sildenafil?
- Take sildenafil for erectile dysfunction about 30 minutes to 1 hour before sexual activity. You can take it any time from 4 hours to 30 minutes before, but 1 hour is ideal.
- Do not take sildenafil more than once in 24 hours for erectile dysfunction.
- For pulmonary arterial hypertension, take sildenafil three times a day with doses spaced 4 to 6 hours apart.
- Take sildenafil with or without food, but avoid high-fat meals before taking it as this can delay its effect.
- If using the liquid form, shake the bottle well for at least 10 seconds before measuring the dose. Use the oral syringe provided and clean it after each use.
- Follow the sildenafil dosage instructions given by your healthcare provider exactly and do not change the dose without medical advice.
- If you are over 65 years old, have liver or kidney problems, or take certain other drugs, your healthcare provider may recommend starting with a lower dose.
- Keep taking sildenafil for pulmonary arterial hypertension even if you feel better, unless your doctor tells you to stop.
- Never mix sildenafil liquid with other liquids or medications unless instructed by your doctor.
Side Effects
Sildenafil can cause a range of side effects, from mild and temporary to more serious reactions that need immediate medical attention.
Being aware of the possible effects, including sildenafil long-term side effects, can help you use it more safely.
Common Side Effects
- Headache
- Heartburn or indigestion
- Diarrhea
- Nausea
- Flushing or a warm feeling in the skin
- Nosebleeds
- Numbness, burning, or tingling in arms, hands, feet, or legs
- Muscle, back, arm, or leg pain
- Changes in color vision, such as a blue tinge or trouble telling blue from green
- Sensitivity to light
- Nasal congestion or a runny nose
Severe Side Effects
- Sudden and severe loss of vision
- Blurred vision
- Sudden decrease or loss of hearing, sometimes with ringing in the ears or dizziness
- Fainting, dizziness, or feeling lightheaded
- Chest pain or pressure
- Worsening shortness of breath
- Painful erection or an erection lasting longer than 4 hours
- Rash, itching, hives, or swelling of the eyes, face, lips, tongue, or throat
- Difficulty breathing or swallowing
- Signs of heart attack, stroke, irregular heartbeat, or bleeding in the brain or lungs
- Any unusual or persistent symptoms that may suggest sildenafil long-term side effects
Missed Dose
If you take sildenafil for erectile dysfunction, you will not usually miss a dose because you take it only when needed before sexual activity.
If you take sildenafil for pulmonary arterial hypertension, take the missed dose as soon as you remember.
If it is almost time for your next scheduled dose, skip the missed dose and take the next one at the regular time. Do not take two doses at the same time to make up for the one you missed.
Taking extra sildenafil can increase the risk of unwanted side effects and possible sildenafil long-term side effects.
Overdose
Taking more sildenafil than prescribed can be dangerous. Symptoms of overdose may include severe dizziness, fainting, chest pain, irregular heartbeat, or a prolonged and painful erection.
If you think you have taken too much, go to the emergency room right away. If you or someone else collapses, has a seizure, has trouble breathing, or cannot wake up, call 911 right away.
Quick action can help prevent serious complications from a sildenafil overdose.
Contraindications
People who take nitrates should not use sildenafil because the combination can cause a dangerous drop in blood pressure.
Individuals with severe low blood pressure from other causes, allergies to its ingredients, pulmonary veno-occlusion, left ventricular outflow obstruction, pulmonary arterial hypertension linked to sickle cell anemia, or multiple system atrophy should avoid it.
People with certain eye conditions, such as ischemic optic neuropathy or inherited retinal disorders, should not take it. Anyone who experiences sudden vision loss must stop using it immediately.
Warnings
- Sildenafil can lower blood pressure. People with certain heart problems or blood pressure control issues should only take it under medical guidance.
- Taking sildenafil with alpha-blockers or other blood pressure drugs can cause a sudden drop in blood pressure, leading to dizziness or fainting.
- Rarely, sildenafil can cause an erection lasting more than 4 hours (priapism). This is a medical emergency because it can damage the penis if not treated quickly.
- People with sickle cell anemia, multiple myeloma, or penis shape abnormalities have a higher risk of priapism and should be closely monitored.
- Men over 50 and those with a history of non-arteritic anterior ischemic optic neuropathy (NAION) or a “crowded” optic disc may be at increased risk of sudden vision loss.
- Drugs that strongly block the liver enzymes CYP3A4 or CYP2C9 (such as ritonavir) can greatly increase sildenafil levels in the body, which may cause side effects. In these cases, the dose should not exceed 25 mg every 48 hours.
- Taking sildenafil with the endothelin antagonist bosentan can reduce sildenafil levels and increase bosentan levels. Also, drugs that boost CYP3A4 activity can make sildenafil less effective.
- If you are taking alpha-blockers, you should start with the lowest dose of sildenafil to avoid dangerous drops in blood pressure.
Interactions
- Nitrates
- Alpha blockers
- Antihypertensive medications
- CYP3A4 inhibitors
- Guanylate cyclase stimulators
- Protease inhibitors
- Antifungal medications
- HIV medications
- Other PDE5 inhibitors
- Rifampin
Storage Information
Store sildenafil at room temperature and keep it away from moisture and heat. Keep the medication in its original packaging to protect it from light and moisture.
Make sure to store it in a place that children and pets cannot reach. Do not use it if it has expired.
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Disclaimer
Pharma Giant provides medical information to help you better understand medications and medical conditions.This content is for informational use only and does not replace advice from a licensed medical practitioner. Consult your doctor or pharmacist before starting or changing any medication. All our partners follow strict safety standards set by their country’s health authorities to make sure you receive safe and high-quality medications.
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