Quick answer: Sildenafil is a prescription PDE5 inhibitor commonly used for erectile dysfunction. It is generally taken when required before anticipated sexual activity, requires sexual stimulation to work and must never be combined with nitrate medicines.
What Is Sildenafil?
Sildenafil belongs to a group of medicines called phosphodiesterase type 5 inhibitors, abbreviated as PDE5 inhibitors. These medicines help certain blood vessels relax by supporting the body’s natural nitric oxide and cyclic guanosine monophosphate pathway.
For erectile dysfunction, this action supports increased blood flow to the penis during sexual stimulation. Sildenafil does not directly create sexual excitement and will not produce an erection simply because a tablet has been taken.
What Are the Main Sildenafil Uses?
1. Erectile Dysfunction
The most widely recognised sildenafil use is the treatment of erectile dysfunction in adult men. Erectile dysfunction, also called ED, is the recurring difficulty in achieving or maintaining an erection firm enough for sexual activity.
ED may be associated with:
- Diabetes or uncontrolled blood sugar
- High blood pressure or high cholesterol
- Heart and blood-vessel disease
- Obesity or limited physical activity
- Smoking or excessive alcohol
- Stress, depression or performance anxiety
- Hormonal or neurological conditions
- Side effects of certain medicines
Sildenafil manages the erectile response but does not necessarily treat these underlying causes. Persistent ED should therefore be assessed by a doctor.
2. Pulmonary Arterial Hypertension
Sildenafil may also be prescribed in specially formulated products for pulmonary arterial hypertension, a condition involving high blood pressure in the blood vessels supplying the lungs.
The strength, brand, schedule and medical supervision used for pulmonary hypertension differ from erectile dysfunction treatment. An ED product should not be used for pulmonary hypertension unless specifically prescribed for that purpose by a specialist.
Important: Do not combine sildenafil prescribed for erectile dysfunction with another sildenafil-containing treatment prescribed for pulmonary hypertension. This can result in excessive total exposure and serious side effects.
How Does Sildenafil Work for Erectile Dysfunction?
During sexual stimulation, the body releases nitric oxide. This contributes to increased levels of a chemical called cyclic guanosine monophosphate, or cGMP, which helps smooth muscle and blood vessels relax.
The PDE5 enzyme normally breaks down cGMP. Sildenafil temporarily reduces PDE5 activity, allowing the natural erectile-response process to continue for longer.
This explains why:
- Sexual stimulation is still required.
- Sildenafil is not an aphrodisiac.
- It does not automatically produce an erection.
- It does not permanently cure erectile dysfunction.
- It does not increase testosterone.
Available Sildenafil Strengths
Common sildenafil tablet strengths used for erectile dysfunction include:
- Sildenafil 25mg
- Sildenafil 50mg
- Sildenafil 100mg
The presence of different strengths allows a doctor to select a dose according to the patient’s health, response, side effects and other medicines. A higher strength is not automatically more suitable or more effective.
Sildenafil 25mg
A lower strength may be considered for patients who experience side effects, use certain interacting medicines, are older, or have particular liver or kidney considerations. The decision must be made by a healthcare professional.
Sildenafil 50mg
Official prescribing information identifies 50mg as a commonly recommended starting strength for many suitable adult patients. This is not a universal dose and does not replace an individual medical assessment.
Sildenafil 100mg
A doctor may consider a higher strength when a lower dose has been insufficient and well tolerated. Patients should not increase their dose independently, because the risk of side effects may also increase.
When Is Sildenafil Usually Taken?
Official prescribing information states that sildenafil for erectile dysfunction is commonly taken approximately one hour before anticipated sexual activity. Depending on medical instructions, it may be taken between 30 minutes and four hours before activity.
The exact timing can be affected by:
- Whether it was taken after a heavy meal
- The prescribed strength
- Individual metabolism
- Existing health conditions
- Other medicines
- Level of sexual stimulation
Do not take an additional tablet simply because the medicine has not worked as quickly as expected.
How Frequently Can Sildenafil Be Taken?
Official prescribing information states that sildenafil for erectile dysfunction should not be taken more than once within 24 hours. Some patients may require less frequent use or a modified dose because of other medicines, liver or kidney function and individual tolerance.
Always follow the prescribed instructions. Do not:
- Take more than one prescribed dose within 24 hours
- Combine two sildenafil brands
- Combine sildenafil with tadalafil
- Increase the strength without medical approval
- Use another person’s prescription medicine
Can Sildenafil Be Taken With Food?
Sildenafil may generally be taken with or without food. However, a large or high-fat meal may delay absorption and cause it to take longer to begin working.
If the effect seems delayed after a heavy meal, do not immediately take another dose. Wait according to the instructions given by your doctor.
Sildenafil and Alcohol
Excessive alcohol can make it more difficult to achieve an erection and may increase dizziness, headache or low blood pressure. Large amounts of alcohol may therefore reduce the expected treatment experience and increase risk.
A person who already experiences dizziness, low blood pressure or cardiovascular concerns should obtain personalised medical advice regarding alcohol.
Common Sildenafil Side Effects
Like all medicines, sildenafil can cause side effects, although not everyone experiences them. Commonly reported side effects include:
- Headache
- Facial flushing
- Indigestion or upset stomach
- Stuffy or runny nose
- Dizziness
- Nausea
- Temporary blurred vision
- Temporary changes in colour perception
- Back or muscle discomfort
Do not drive or operate machinery if sildenafil causes dizziness, blurred vision or another symptom that affects concentration.
Serious Sildenafil Side Effects
Serious reactions are less common but require urgent attention.
Seek immediate medical assistance for:
- Chest pain or severe pressure in the chest
- Fainting or severe dizziness
- A fast or irregular heartbeat accompanied by illness
- An erection lasting longer than four hours
- Sudden loss or reduction of vision
- Sudden loss or reduction of hearing
- Seizures
- Difficulty breathing or signs of a serious allergic reaction
An erection lasting more than four hours is a medical emergency. Delayed treatment can cause permanent damage.
Sildenafil and Nitrates
Critical warning: Sildenafil must never be combined with nitrate medicines or recreational “poppers.” The combination can cause a sudden and dangerous reduction in blood pressure.
Nitrate medicines may include:
- Nitroglycerin
- Glyceryl trinitrate or GTN
- Isosorbide mononitrate
- Isosorbide dinitrate
- Amyl nitrate or amyl nitrite “poppers”
Nitrates can be supplied as tablets, sprays, patches, ointments or medicines placed under the tongue. If you are unsure whether a heart medicine contains a nitrate, consult your doctor or pharmacist before using sildenafil.
Important Sildenafil Interactions
Tell your doctor or pharmacist about every prescription medicine, non-prescription product, vitamin and herbal supplement you use.
Particular caution may be required with:
- Riociguat
- Alpha-blockers such as tamsulosin or doxazosin
- Other blood-pressure medicines
- Certain HIV protease inhibitors
- Certain antifungal medicines
- Certain antibiotics
- Other PDE5 inhibitors or ED treatments
- Other products containing sildenafil
Some interacting medicines can increase sildenafil levels or produce an excessive blood-pressure reduction. A doctor may need to alter the strength, frequency or treatment choice.
Who Should Obtain Medical Advice Before Sildenafil?
A detailed medical assessment is particularly important if you:
- Have heart disease, chest pain or heart failure
- Recently experienced a heart attack or stroke
- Have an irregular heartbeat
- Have very low or uncontrolled high blood pressure
- Have severe liver or kidney disease
- Receive kidney dialysis
- Have a bleeding disorder or active stomach ulcer
- Have a penile deformity
- Previously experienced a prolonged erection
- Have sickle-cell anaemia, leukaemia or multiple myeloma
- Have retinitis pigmentosa or a history of serious vision loss
Sexual activity can place additional strain on the heart. A doctor may need to assess whether sexual activity and ED treatment are medically appropriate for a patient with cardiovascular disease.
What Sildenafil Does Not Do
Sildenafil is frequently misunderstood. It does not:
- Increase sexual desire
- Increase testosterone levels
- Increase fertility or sperm count
- Automatically delay ejaculation
- Cause an erection without stimulation
- Permanently cure erectile dysfunction
- Protect against HIV or other sexually transmitted infections
Why Might Sildenafil Not Work as Expected?
A reduced or delayed response does not always mean sildenafil is unsuitable. Possible reasons include:
- Insufficient sexual stimulation
- Taking it after a heavy meal
- Incorrect timing
- Excessive alcohol consumption
- Performance anxiety
- An unsuitable prescribed strength
- A significant underlying medical condition
- Use of an unregistered or falsified product
Do not increase the dose yourself. A doctor can review timing, technique, medicine interactions and possible underlying causes.
Sildenafil vs Tadalafil
Sildenafil generally has a shorter treatment window, whereas tadalafil may remain effective for up to 36 hours. Tadalafil may also be prescribed in a lower once-daily regimen for suitable patients.
Neither medicine is universally better. For a detailed comparison, read our sildenafil vs tadalafil guide.
Sildenafil Brands and Products in Pakistan
Sildenafil is available under different brand names and strengths. Products listed on HomeoShop.PK may include Viagra, Silagro and other sildenafil options according to current availability.
When comparing products, check:
- Active ingredient
- Strength per tablet
- Manufacturer or licence information
- Pack size
- Batch number and expiry date
- Packaging condition
- Prescription requirement
Browse currently available products in the Erectile Dysfunction medicines category.
Fake or Unregistered Sildenafil Products
DRAP has published alerts concerning falsified, spurious and unregistered aphrodisiac products, including certain sildenafil products. Unregistered medicines may contain an incorrect dose, undeclared ingredients, harmful substances or no effective ingredient.
Reduce risk by avoiding:
- Loose or unlabelled tablets
- Packs without batch and expiry information
- Opened, altered or poorly printed packaging
- Products making “100% safe” or “no side effects” claims
- Unknown sellers operating only through social media
- Products without clear manufacturer information
If a pack appears suspicious, do not use it. Consult a pharmacist and check the latest DRAP alerts.
Frequently Asked Questions
What is sildenafil mainly used for?
Sildenafil is commonly prescribed for erectile dysfunction in adult men. Specially formulated sildenafil products may also be prescribed for pulmonary arterial hypertension under specialist supervision.
How long before sexual activity is sildenafil taken?
Official information states that it is commonly taken approximately one hour before anticipated sexual activity and may be taken between 30 minutes and four hours beforehand, according to medical instructions.
Does sildenafil work without sexual stimulation?
No. Sildenafil supports the body’s natural erectile response and requires sexual stimulation to work.
Can sildenafil be taken after food?
It may generally be taken with or without food, but a large or high-fat meal can delay its onset.
Can sildenafil be taken every day?
Do not take sildenafil more frequently than prescribed or more than once within 24 hours. Whether repeated use is appropriate should be determined by a doctor.
Is sildenafil 100mg better than 50mg?
Not automatically. Higher strengths may increase side effects and are not appropriate for every patient. A doctor should determine the suitable strength according to response and tolerance.
Is Viagra the same as sildenafil?
Viagra is a brand containing sildenafil. Other products can contain the same active ingredient but differ in strength, manufacturer, pack size and inactive ingredients.
Is Silagro a sildenafil medicine?
Silagro products are associated with sildenafil. Always confirm the active ingredient and strength printed on the individual pack.
Can sildenafil be taken with tadalafil?
These medicines should not be combined unless specifically prescribed and supervised by an appropriate specialist.
Can a heart patient use sildenafil?
Some heart patients may be unsuitable for sildenafil. Anyone using nitrates must not take it. Cardiovascular assessment may be necessary before treatment.
Can sildenafil cause permanent damage?
Most side effects are temporary, but rare serious reactions such as an erection lasting longer than four hours or sudden vision or hearing loss require urgent treatment to reduce the risk of lasting harm.
Reviewed Sources
- Official sildenafil prescribing information
- Official sildenafil patient information
- NHS sildenafil information
- DRAP falsified and unregistered product alert
Medical Disclaimer: This article provides general educational information and does not replace medical advice, diagnosis or treatment. Sildenafil is a prescription medicine. Use it only after assessment by a registered healthcare professional.
[…] our complete Sildenafil Uses, Timing, Side Effects and Safety Guide for further […]