Sildenafil Tablets

Sildenafil is used to treat both:

• Erectile dysfunction; and
• Pulmonary arterial hypertension (PAH)

It became well-known as the active ingredient in another erectile dysfunction treatment, Viagra, but is as available as a lower-cost Viagra alternative. In June 2013, Pfizer’s patent for Viagra expired, opening a market for generic sildenafil citrate. As a result, men now have a choice between branded Viagra and more affordable generic sildenafil tablets.

Prescription only – Sildenafil is a prescription medication, meaning that it's only available on prescription and should be taken exactly as prescribed to be fully effective. You can order sildenafil tablets online from our team of doctors and have them delivered to the (UK) address of your choice.

For a non-prescription medication with the same active ingredient as Viagra, see Viagra Connect.

The main difference is the cost – Because generic Sildenafil is not branded as Viagra it can be bought for cheaper.

There is no difference in the effect of the medications – Viagra is the brand name for the generic medicine known as Sildenafil. Sildenafil and Viagra are ‘medically equivalent’, meaning that they both work in the same way, and contain the same active ingredients.

A big difference coming soon – Viagra and Sildenafil are both prescription medications but from Spring 2018, Viagra Connect will be available. This is a new form of over-the-counter Viagra that will not require a prescription.

Sildenafil tablets are used to treat erectile dysfunction – this is when a man repeatedly has problems getting or keeping an erection. Sildenafil treats erectile dysfunction by relaxing the blood vessels in your penis, which allows the blood flow to increase. Good blood flow to the penis is necessary for a strong and healthy erection.

Would Sildenafil tablets force me to have an erection? – not normally. Sildenafil is not an aphrodisiac. It will not make you sexually stimulated or raise your libido on its own. It isn’t designed to cause erections on it’s own, although it can rarely cause a side effect called priapism where erections are painful and won’t go away.

Yes in small quantities – you can drink up to 2-3 units of alcohol, safely, while taking sildenafil. Many people find that alcohol helps them overcome their anxieties around sex.

However, alcohol can interfere with your treatment - too much alcohol can make your problems with erectile dysfunction worse. Drinking more than 2-3 units might have a negative effect on your sexual function.

Always take your medication exactly as it was prescribed to you by your doctor.

When you take Sildenafil:

• As a rule, you should take your sildenafil tablets up to 1 hour before having sex (although it can get to work anywhere between 30 minutes and 4 hours after you take it).
• Swallow your sildenafil tablets whole, without chewing or crushing them.
• Take your sildenafil tablets with or without water, as desired.
• Only take 1 per day.

Things to avoid:

• Heavy meals – Sildenafil works best on an empty stomach. It won’t get to work as fast after eating a heavy, high-fat meal.
• Grapefruit juice – drinking grapefruit juice while taking Sildenafil can increase your chance of getting side effects
• Changing your dosage on your own – do not start, stop, or change your intake of Sildenafil tablets without first discussing it with your doctor.
• Avoid alcohol

Check whether you can drive – a common Sildenafil side effect is loss of vision or bouts of dizziness, therefore do not drive, operate machinery or engage in any task that requires intense concentration or alertness until you are confident that this side effect doesn't apply to you.

If you’re an older person – take this medication with caution as its effects can be more pronounced for you.

Sildenafil is not for everyone – you should not start taking Sildenafil tablets without first consulting your doctor or pharmacist. Inform them of your full medical history, paying particular attention to the following:

• Sickle cell disease
• High or low blood pressure
• Dehydration
• Priapism (painful erection problems)
• Eye problems (such as blurred or loss of vision in one or both eyes)
• Heart problems (arrhythmia, angina, heart attack, aortic stenosis etc)
• Kidney disease
• Liver disease
• Fluid in the lungs
• Problems with the shape of the penis (angulation, fibrosis/scarring)
• Stroke in the past 6 months

Sildenafil is the active ingredient in Viagra. It causes the release of nitrous oxide (NO), a chemical that enlarges the blood vessels in the penis during sexual stimulation. This allows for the necessary inflow of blood needed to cause an erection.

Sildenafil comes in 3 dosages:

• 100mg
• 50mg
• 25mg

How do I know which dosage I need? – a doctor will decide the right dose for you during your assessment. The Sildenafil dosage you need to take will depend on your age, gender, medical condition, your response to therapy and use of any interacting medication. 25, 50 and 100mg Sildenafil tablets are available.

The recommended dose for most people is 50mg – this is taken between 30 minutes and four hours prior to sexual activity. This dose can be increased to 100mg or decreased to 25mg depending on whether or not you get the results you want, or if you experience any side effects.

The following patients should stick to no more than 25mg Sildenafil tablets:

• Those over 65 years of age
• Those with liver failure
• Those with a creatinine clearance <30ml/min
• Those using potent cytochrome P450 inhibitors

Not everyone will get side effects but there is a chance Sildenafil tablets could cause some.

When using this medication, you may experience one or more of the following, common Sildenafil side effects:

• Dizziness/ lightheadedness
• Headache
• Flushing
• Heartburn or indigestion
• Nosebleeds or nasal congestion
• Trouble sleeping
• Oedema (swollen hands, ankles or feet)
• Visual disturbances (blurred vision/ increased sensitivity to light/ blue-green colour blindness)

If any Sildenafil side effects get worse over time, or are particularly uncomfortable, talk to your doctor or pharmacist.

If you experience any of the following, serious side effects during sex and you have outstanding heart problems, stop taking Sildenafil and get medical help:

• Severe dizziness
• Fainting
• Chest/ jaw/ left arm pain
• Nausea

If you experience any of the following side effects, it indicates than an allergic reaction has occurred, (although rare, this is a serious problem and you should seek medical attention at once):

• Rash
• Itching/ swelling (particularly of the face, tongue and throat)
• Severe dizziness
• Trouble breathing

If you experience a sudden loss of hearing in one or both ears, or a ringing in your ears while using Sildenafil tablets, consult a doctor at once.

If you experience a sudden loss of eyesight in one or both eyes (NAION) stop taking the medication, and consult a healthcare professional at once. This is a very rare Sildenafil side effect, although your chances of experiencing it increases if you already suffer from any of the following:

• Heart disease
• Diabetes
• High cholesterol
• High blood pressure
• Existing eye problems
• You are over 50
• You are a smoker

Yes, let the doctor assessing you know your current medications – Whether taking Sildenafil 100mg, 50mg or 25mg, you should keep a list of all the products you use (including prescription/ non-prescription and herbal medication) and share it with your doctor or pharmacist.

Avoid nitrates – Sildenafil must not be taken with any form of nitrate medication as this combination can produce a severe drop in blood pressure that can cause dizziness, fainting, or even heart attack. Nitrate medications, supplements, and other drugs include the following:

• Glyceryl trinitrate, isosorbide mononitrate and isosorbide dinitrate (used for angina or heart failure – if you experience chest pain after taking Sildenafil DO NOT use nitrates to treat it)
• Nicorandil
• Amyl nitrate 'poppers'

Some other products that may negatively interact with sildenafil are:

• Alpha blockers (doxazosin, prazosin, terazosin)
• HIV drugs (ritonavir, saquinavir, delavirdine)
• St John's Wort
• Cimetidine
• Anticonvulsants (carbamazepine, phenobarbital, phenytoin)
• Azole antifungals
• Macrolide antibiotics (erythromycin, rifamycins)

Electronic Medicines Compendium (2014). Sildenafil 50 mg film-coated tablets. Milipharm Limited. [online] Available at: https://www.medicines.org.uk/emc/files/pil.7124.pdf?filename=PIL.7124.pdf [accessed 9th January 2018].