Sildenafil is the generic form of the branded tablet Viagra. Both Sildenafil and Viagra contain the same active ingredient, sildenafil citrate. Sildenafil can be used to treat erectile dysfunction (where you can’t get or keep erections). Sildenafil is also sometimes used by specialists to treat high blood pressure in the lungs, as well as certain types of peptic ulcers.

Sildenafil usually comes as a tablet, although it is available as an oral suspension or gel. In the UK Sildenafil is only available in tablet form for treating erectile dysfunction.

Sildenafil belongs to a group of popular erectile dysfunction treatments called phosphodiesterase type-5 (PDE-5) inhibitors. These medications work by increasing blood flow to certain parts of the body, including the penis. This means that they make getting and keeping an erection easier once you’re aroused. Specifically, PDE-5 inhibitors work by blocking the action of PDE-5 which reduces blood flow to areas like the penis.

How long does Sildenafil last?

Sildenafil usually lasts for around 4-6 hours, but it might last for a shorter or longer time for you. This means that if you are sexually aroused during this time, Sildenafil will be able to help you get and maintain an erection more easily. This does not mean that you should expect erections to last 4-6 hours when taking Sildenafil. The only way to find out exactly how long Sildenafil will work for you is to try it and see how long it lasts for yourself.

How quickly does Sildenafil work?

It usually takes 30-60 minutes for Sildenafil to work and we recommend you try to take it 1 hour before you want to try and have sex. Since it does last up to 6 hours, you can take it earlier but the effect will be strongest around the 1-hour mark. Sildenafil may take longer to work if you take it right after eating, since food will slow down how fast your body absorbs the medication.

How effective is Sildenafil?

Studies show that Sildenafil is effective at treating erectile dysfunction for most people who try it. An average of 69% of men with erectile dysfunction are able to have successful sexual intercourse with sildenafil, compared to only 35.5% with a placebo (a tablet without any medication in).

Sildenafil could help you get and keep erections but it doesn’t work for everyone. The only way to know for sure is to give it a go yourself. If you find after 8 attempts Sildenafil doesn’t work for you, you should think about trying an alternative treatment.

You should take each tablet whole, with a drink of water or juice. Do not take Sildenafil with grapefruit juice as this affects how the tablets work. Sildenafil works best if you take it on an empty stomach, although it can be taken safely with food, but it may get to work more slowly. You should take sildenafil around 1 hour before you want to have sex.

Advice on taking sildenafil should be included in the patient information leaflet that comes with the medication.

Sildenafil dosage

Sildenafil tablets come in 3 different doses, 25mg, 50mg and 100mg. You should only take the dose that is prescribed to you by a doctor or pharmacist. The usual dose is 50mg which is taken no more than once per day, when you need it. This dose can be increased to 100mg or decreased to 25mg, depending on how sildenafil affects you:

• If you find that 50mg doesn’t work as well as you’d like, and you don’t have problems with side effects, you could try 100mg.
• If you find 50mg works well for you but comes with side effects that bother you, you could drop down to 25mg, which may still improve your erections but come with less intense side effects.

When to take Sildenafil

You should take sildenafil around 1 hour before you want to have sex. Sildenafil takes at least 30 minutes to work, so take it at least 30 minutes before you want to have sex. Sildenafil takes longer to work if you eat before you take it so take that into consideration when timing your dose.

How often to take Sildenafil

You should only take Sildenafil when you need it – when you’re planning to attempt sex. It’s only safe to take Sildenafil once every 24 hours, otherwise you risk serious side effects. You can take Sildenafil every day if needed.

How long do you need to take Sildenafil for?

You should only take Sildenafil when you need it to treat your erection problems and you want to have sex. If you do not have erectile dysfunction or you don’t want to have sex, you do not need to take sildenafil.

Sildenafil does not cure erectile dysfunction, so you may need to keep taking it to help support your erections. If your erectile dysfunction improves because of lifestyle changes or other factors, you may find you no longer need to use Sildenafil.

You can request Sildenafil online from trusted suppliers such as Superdrug Online Doctor. First, you will need to fill out a short questionnaire about your health. A GMC-registered doctor will then check your answers and approve Sildenafil treatment if it’s right for you. You can then have it delivered to your house or you can collect from your nearest Superdrug pharmacy.

If you get a prescription from a GP for Sildenafil, you can get it filled at most UK pharmacies.

Can I buy Sildenafil over-the-counter?

Generic Sildenafil is a prescription-only treatment which means you can’t buy it in a pharmacy without being assessed by a doctor first. However, Viagra Connect is a branded medication which contains sildenafil and is available over-the-counter. This means you can get assessed for Viagra Connect treatment in a pharmacy without seeing a doctor first. The pharmacist will ask similar questions that a doctor would before approving treatment.

Viagra Connect is also available to request online from services like Superdrug Online Doctor.

Can I get Sildenafil on the NHS?

If you have erectile dysfunction, you may be able to get Sildenafil on the NHS. You will first need to be assessed by a doctor. If Sildenafil is suitable for you, you will be given a prescription for Sildenafil which you can get filled at most UK pharmacies. In this case, you would only pay the standard NHS prescription fee.

Like all medications, Sildenafil can cause side effects for some people, however they do not affect everyone. Most side effects from Sildenafil are mild and go away on their own, although more serious ones are possible too. Side effects can be considered common, uncommon, rare or very rare, based on how many people they affect.

Common side effects (affecting more than 1 in 100 people):

• cough
• diarrhoea
• feeling dizzy
• feeling nervous
• feeling sick
• hair loss
• headache
• increased risk of infection
• night sweats
• nose problems
• skin problems
• sleeping problems (insomnia)
• stomach discomfort
• swelling of the arms or legs
• tremor
• vision problems

Uncommon side effects (affecting less than 1 in 100 people):

• being sick
• bleeding
• chest pain
• dry eyes
• dry mouth
• eye problems
• feeling hot
• feeling tired
• heart problems (arrhythmia and palpitations)
• high blood pressure
• nasal congestion
• numbness
• ringing in the ear (tinnitus)
• swelling of the breasts in men (gynaecomastia)
• vertigo

Rare or very rare side effects (affecting less than 1 in 1000 people)

• being irritable
• blood in the semen
• eye problems (glaucoma, optic neuropathy, arteriosclerotic retinopathy, retinal occlusion)
• fainting
• hearing problems
• heart attack
• prolonged erection
• reduced sensation in the mouth
• seizure
• severe skin reactions
• stroke
• sudden death
• throat tightness

How long do side effects last?

If you get any side effects from Sildenafil, they are likely to go away within a day. Talk to a doctor if you have any side effects that don’t go away or are bothering you. According to the NHS, headaches, which are a common side effect, usually go away after about a week.

What to do if you get Sildenafil side effects

If you have persistent or bothersome side effects, talk to a doctor or pharmacist.

There are some things you can do to help manage mild Sildenafil side effects, including:

• staying properly hydrated to improve headaches
• avoiding rich or spicy foods to improve nausea
• avoiding alcohol and caffeine to improve facial flushing
• lying down and resting if you feel dizzy
• use a decongestant nasal spray if you have a stuffy nose

If you have a serious side effect, you should seek immediate medical help. Serious side effects of Sildenafil are:

• seizures or fits
• painful erection or erection lasting over 2 hours
• chest pain

Some people might also be allergic to Sildenafil. Call 999 if you:

• having sudden swelling of your lips, throat, mouth or tongue
• are suddenly short of breath or are finding it difficult to breath
• feel faint or dizzy
• feel your throat is tight and it is difficult to swallow
• get a rash that is swollen, raised, red, itchy or blistering.
• notice your skin becomes pale, grey or blue

You should not take Sildenafil if you:

• are allergic to sildenafil
• are taking medications called nitrates (for angina)
• have a bleeding problem (e.g. haemophilia)
• have a deformity of your penis or have Peyronie’s disease (curved penis)
• have a rare inherited eye disease (e.g. retinitis pigmentosa)
• have a serious heart or liver problem
• have a stomach ulcer
• have low blood pressure
• have recently had a heart attack, heart problem or stroke
• have sickle cell anaemia, leukaemia or multiple myeloma

If you are not sure whether Sildenafil is suitable for you, speak to a doctor or pharmacist.

There are other medications that can be used to treat erectile dysfunction, if you’re not sure that Sildenafil is the right choice for you.

Viagra works in the same way as Sildenafil as they both contain the same active ingredient, sildenafil. However, as Viagra is a branded tablet, it is more expensive than Sildenafil.

Tadalafil is similar to Sildenafil, they are both phosphodiesterase-5 inhibitors and work in a similar way. However, tadalafil lasts longer than Sildenafil – up to 36 hours. Tadalafil comes as a tablet, with a standard dose of 10mg. Tadalafil also comes as a branded medication under the name ‘Cialis’.

Cialis is a long-lasting branded erectile dysfunction medication, which contains the active ingredient tadalafil. It is available as a tablet that can be taken on demand, daily or an over-the-counter version called Cialis Together.

Vardenafil is also similar to Sildenafil, they are both phosphodiesterase-5 inhibitors and work in a similar way. Vardenafil is taken as a tablet, without water, at a dose of 10mg or 20mg.

You can also try to improve your erection without using medications. Some things that might be useful are:

• a vacuum pump for your penis, such as the VaxAid penis pump
• psychological treatment (e.g. talking therapy)
• implants into the penis
• pelvic floor muscle exercises

You should talk to your doctor or pharmacist about treatments for erectile dysfunction and they will be able to recommend ones that are most suitable for you.