Sildenafil

What is Sildenafil and how does it differ from Viagra?

Sildenafil is the active ingredient in the well-known ED medicine Viagra. Until 2013, Pfizer held exclusive rights to sildenafil. Once the patent expired, pharmaceutical companies were permitted to manufacture generic sildenafil, which contains the same active ingredient in the same strength as the original.

Generic medicines provide identical clinical efficacy and safety. For this reason, sildenafil tablets are considered a true Viagra equivalent:

• Same active ingredient (sildenafil citrate)
• Same absorption and concentration profile
• Comparable safety and efficacy

Although tablet shape, colour and packaging vary, the clinical effect of sildenafil remains the same.

Is Viagra better than Sildenafil? Core differences

1. Sildenafil Price: Generic sildenafil is cheaper than branded Viagra because generics do not require investment in research, development or branding.
2. Appearance: Generic products differ in colour, shape, and imprint. Viagra is protected as a blue, diamond-shaped tablet. Generics can be round, oval, or other colours.
3. Excipients: While the active ingredient is identical, excipients such as binders, colourants, or fillers may differ. Rarely, patients sensitive to certain excipients may experience reactions.
4. Manufacturer: Sildenafil is produced by various pharmaceutical companies, and Viagra exclusively by Pfizer.

Some generics may differ slightly in onset time by a few minutes, but overall efficacy remains the same.

How does Sildenafil work?

Sildenafil is a PDE-5 inhibitor. During sexual stimulation, nitric oxide (NO) triggers the production of cGMP, which relaxes the smooth muscle in penile arteries. This increases blood flow and enables an erection.

PDE-5 enzymes break down cGMP, causing an erection to subside. Sildenafil temporarily inhibits this breakdown so cGMP remains active longer, enabling stronger erections when sexually aroused.

Sildenafil does not increase sexual desire; it enhances the physical response to stimulation.

Buying Sildenafil in the UK:  Regulations and Advice

Prescription

Buying Sildenafil without a prescription is illegal in the UK and not permitted for medical reasons. This applies to Viagra as well as all generic versions of sildenafil. This also applies if you wish to buy Sildenafil online.

Prescription requirements protect your health: A doctor must check before prescribing sildenafil whether it is suitable for you, whether there are any dangerous interactions with other medications, and whether there are any pre-existing conditions that would contraindicate its use. This is the only way to minimise serious side effects and health risks.

Buying Sildenafil over the counter and/or from unverified websites carries a high risk of counterfeit or contaminated products.

Venue

With a valid prescription from your doctor, you can buy Sildenafil at any pharmacy in the UK. The pharmacist can advise you on its correct use. 

When you order Sildenafil online, you can compare the prices of different generic Sildenafil products and often benefit from cheaper offers.

Never buy Sildenafil without a prescription from disreputable online vendors. Such offers are illegal and extremely dangerous.

To save money

Larger packs often offer a better price for Sildenafil.

Who is Sildenafil suitable for?

Sildenafil is suitable for adult men aged 18 and over who suffer from erectile dysfunction. Erectile dysfunction means that a man is repeatedly unable to achieve or maintain an erection sufficient for sexual intercourse.

Sildenafil Dosage for ED

Typical strengths are 25 mg, 50 mg, and 100 mg.

The standard starting dose is 50 mg, taken about one hour before sex.

Depending on effect and tolerability, a doctor may reduce the dose to 25 mg or increase it to 100 mg.

Do not take sildenafil more than once per day.

How to take Sildenafil?

• Time of intake: 30-60 minutes before sexual activity
• Frequency: Maximum once daily
• Minimum interval: 24 hours between receipts
• Sildenafil dosage: Swallow the tablet whole with a glass of water.
• Meals: Can be taken with or without food, but high-fat meals delay the onset of action.
• Sildenafil and alcohol: Avoid excessive alcohol consumption

Follow your doctor's instructions carefully. When used correctly, Sildenafil leads to successful erections in 70-80% of men.

When should Sildenafil not be used?

Absolute contraindications:

• Simultaneous intake of nitrates or nitric oxide donors (e.g., glyceryl trinitrate, isosorbide mononitrate, molsidomine, amyl nitrite) - life-threatening due to massive drop in blood pressure
• Concomitant use of guanylate cyclase stimulators such as riociguat (for pulmonary hypertension)
• Known hypersensitivity to sildenafil or other ingredients
• Severe cardiovascular disease, when sexual activity is not advisable
• Recently suffered a heart attack (within the last 3 months)
• Recent stroke (within the last 6 months)
• Severe liver failure (Child-Pugh class C)
• Low blood pressure below 90/50 mmHg
• Unstable angina pectoris
• Severe heart failure (NYHA class 4)
• Previous vision loss due to non-arteritic anterior ischemic optic neuropathy (NAION)
• Concomitant use of strong CYP3A4 inhibitors (ritonavir, ketoconazole, clarithromycin), as sildenafil levels can rise to dangerous levels
• Congenital degenerative retinal diseases, such as retinitis pigmentosa

Relative contraindications (caution advised):

• Anatomical deformities of the penis (e.g., angulation, cavernous fibrosis, Peyronie's disease)
• Diseases that can lead to priapism (e.g. sickle cell anaemia, leukaemia, multiple myeloma)
• Active stomach ulcers
• Blood clotting disorders (e.g., haemophilia)
• Severe renal impairment (dose adjustment may be required)
• Concomitant use of alpha-blockers (risk of hypotension unless blood pressure is stable)

Sildenafil is not approved for women or persons under 18 years of age.

What side effects can Sildenafil cause?

Frequency	Side effects
Frequent (1% to 10%)	Headaches, facial flushing, digestive problems
Occasionally (0.1% to 1%)	Dizziness, visual disturbances, ringing in the ears
Rare (0.01% to 0.1%)	Nosebleeds, skin rash, chest pain, palpitations, fainting
Very rare (<0.01%)	Penile bleeding, priapism (painful permanent erection)

This list is not exhaustive. Seek medical advice for any concerning symptoms.

Sildenafil alternatives

Other PDE5 inhibitors for the treatment of erectile dysfunction are:

• Tadalafil (generic Cialis) – effective for up to 36 hours
• Vardenafil (generic Levitra) – effective for 4-6 hours
• Avanafil (Spedra) – fastest onset of action from 15 minutes

Choosing the right ED medication depends on your individual needs, health conditions and preferences. Your doctor will be happy to advise you on your choice.

Experiences with Sildenafil

Generic sildenafil offers the same effectiveness as the original ED medication and convinces many users, both scientifically and in everyday life:

At 64, I didn't have erectile dysfunction, but I couldn't always maintain an erection during sex or wasn't hard enough for some positions. I got a prescription for generic [ sildenafil] 50 mg. I tried it twice, split into 25 mg doses. I wanted to test the side effects. The 25 mg helped me get a little harder, but it mainly helped with the recovery time (I could get going again almost immediately). The 50 mg, however, was like a rejuvenating treatment: a full, firm erection that I could maintain until orgasm, as often as I wanted and in any position. I'm convinced! A mild side effect of facial flushing occurred with the 50 mg dose, but it wasn't very strong. I also had a headache later (about one to two hours after the half-life). (drugs.com )

Further information

Package leaflet of Sildenafil 25mg / 50mg / 100 mg for download.