Buy sildenafil tablets (generic Viagra) online

  • Highly effective and clinically proven
  • Delivered straight to your door, in plain and discreet packaging
  • Generic form of Viagra
  • Available from just £7 + prescription fees and delivery costs

Our prices

Strength Quantity Price Stock
25mg4 tablets£7.00In Stock
25mg8 tablets£13.00In Stock
25mg12 tablets£20.00In Stock
25mg16 tablets£25.00In Stock
25mg24 tablets£36.00In Stock
25mg28 tablets£40.00In Stock
25mg32 tablets£45.00In Stock
25mg64 tablets£60.00In Stock
50mg4 tablets£8.45In Stock
50mg8 tablets£15.45In Stock
50mg12 tablets£21.00In Stock
50mg16 tablets£26.05In Stock
50mg24 tablet£38.99In Stock
50mg28 tablets£45.00In Stock
50mg32 tablets£47.99In Stock
50mg64 tablets£64.94In Stock
100mg4 tablets£9.05In Stock
100mg8 tablets£17.05In Stock
100mg12 tablets£24.00In Stock
100mg16 tablets£27.65In Stock
100mg24 tablets£39.99In Stock
100mg28 tablets£45.00In Stock
100mg32 tablets£49.95In Stock
100mg64 tablets£91.99In Stock
Prices exclude a prescription fee. This treatment requires a quick online consultation,
which a doctor will review to determine if a prescription is appropriate.

Safe and discreet

  • Safe and regulated treatments
  • 100% discreet and confidential
  • UK qualified doctors
  • Fully registered UK pharmacy


Dr Samantha Miller

Reviewed by Dr Samantha Miller MB ChB
(2017, University of Glasgow)
GMC number: 7561464

Information last reviewed 16/03/2022


What is sildenafil?

Sildenafil (generic Viagra) is a treatment for erectile dysfunction (ED). It works in combination with sexual stimulation to help a man gain and maintain an erection for long enough to engage in sexual activity. Sildenafil, like Viagra, comes in 25mg, 50mg and 100mg tablets.

How effective is sildenafil?

Sildenafil is very effective with at least 2/3 of men reporting an improvement with use, and up to 84% of men reporting improvement in studies using a dose of 100mg. Erectile dysfunction can vary a lot between people and it’s common to trial several doses or several different therapies before finding the one that works best for you. To help you, an ED Trial Pack is available that contains a selection of the most popular ED medications at a range of doses.

How does sildenafil work?

Sildenafil, like other medicines in its family (PDE5 inhibitors) works by relaxing the blood vessels that supply the penis. This improves blood flow, making it easier to achieve and maintain an erection when sexually stimulated. Sildenafil should not give you an erection if you are not sexually aroused or excited. 

When you first start taking sildenafil, you may not experience effects straight away. It takes 30-60 minutes to absorb and doctors recommend you try sildenafil several times over a period of a few weeks to see if it works for you.

Sildenafil summary


Take ONE tablet 30 to 60 minutes before sexual activity

Type of medicine PDE5 inhibitor

Improved blood flow into the penis

Available Size

4 to 64 tablets

Available Strengths

25mg, 50mg & 100mg

Active Ingredient

Sildenafil citrate


From 94p per dose

Side Effects

Can include headaches, facial flushing, dizziness and nasal congestion


Active ingredient

The active ingredient in sildenafil is sildenafil citrate.

Inactive ingredients

The inactive ingredients that make up the rest of the tablet are calcium hydrogen phosphate anhydrous, cellulose microcrystalline, croscarmellose sodium, silica colloidal anhydrous, magnesium stearate, lactose monohydrate, hypromellose 15cP, titanium dioxide (E171) and triacetin.

Note that inactive ingredients may differ depending on the manufacturer.


How to take sildenafil

The following is general advice, always take sildenafil as instructed by a doctor or pharmacist. Swallow one tablet whole with a glass of water approximately an hour before sexual activity. Sildenafil may take longer to work if you have just eaten a heavy or fatty meal. 

If you feel that your dose is too weak or too strong, speak to your doctor who may alter your dosage. Do not take sildenafil more than once per day.

Sildenafil starting dosage

The recommended starting dose of sildenafil is 50mg. Your doctor will normally recommend you try this on several occasions over a period of a few weeks. 

If you find it is too effective but causing side effects, your doctor may recommend 25mg sildenafil. If you find it’s not working as expected, speak to your doctor who may increase your dose to sildenafil 100mg tablets. Exceeding 100mg daily will not increase its effectiveness, but will increase the risk of side effects.

Side Effects

Sildenafil side effects

Like all medications, sildenafil can cause side effects in some, but not all patients. If you experience any of the following serious but rare side effects, stop taking sildenafil and seek medical help immediately:

  • An allergic reaction with symptoms including wheezing, difficulty breathing and swelling of the eyelids, face, lips or throat.
  • Chest pain. If this occurs, get into a semi-sitting position and try to relax, and do NOT use nitrates (e.g. GTN spray) to treat your chest pain.
  • Prolonged (>4 hours) or painful erections
  • Sudden decrease or loss of vision
  • Serious skin reaction including severe peeling, swelling, blistering of the mouth, genitals or skin around the eyes, and fever

The most common side effects of sildenafil are headaches which may affect more than 1 in 10 people.

Other common side effects (affecting up to 1 in 10 people) are:

  • Nausea
  • Flushing, particularly of the face
  • Indigestion
  • Visual disturbance including colour distortion and blurred vision
  • Congested nose
  • Dizziness

There are other potential side effects that occur infrequently to very rarely, to find out more visit the Sildenafil patient information leaflet.

How to reduce sildenafil side effects

The most common side effect of sildenafil use is a headache which is reported to occur in more than 10% of users. Headaches can be managed with hydration and over-the-counter painkillers, such as paracetamol or ibuprofen, where necessary. If you experience facial flushing, try and stay cool by applying a cool compress, breathing deeply and trying to relax. 

If any side effects are particularly severe or prolonged, or if you frequently experience stomach upset when taking sildenafil, speak to a doctor or pharmacist for advice. A doctor may recommend an alternative ED treatment.


There are some people for which Sildenafil would not be appropriate. These are identified by our doctors when they review your health assessment so ensure you provide accurate information.

It is important that people with the following do NOT take sildenafil:

  • Allergies to sildenafil or any of the other ingredients

  • Uncontrolled high or low blood pressure

  • Unstable heart disease or unstable angina

  • Severe heart or liver problems

  • A recent stroke or heart attack

  • A family history of degenerative eye diseases

  • Are taking nitrites e.g. for angina

  • Use “poppers” (butyl nitrate)

Drug interactions

Before taking sildenafil, tell your doctor or pharmacist if you are taking any other medications, including those purchased over the counter without a prescription. 

Do not take sildenafil along with:

  • Medicines containing nitrates, e.g. glyceryl trinitrate (GTN), isosorbide mononitrate, nicorandil, amyl nitrate
  • “Poppers” which contain amyl nitrate or butyl nitrate

In particular, speak to your doctor if you take:

  • Other treatments for erectile dysfunction
  • Other PDE-5 inhibitors e.g. for the treatment of pulmonary arterial hypertension
  • Alpha-blockers such as doxazosin, prazosin
  • Medications used to treat HIV e.g. ritonavir
  • Anti-infective medications such as ketoconazole, itraconazole, erythromycin, cimetidine.

Sildenafil and alcohol

While sildenafil doesn’t directly interact with alcohol, drinking alcohol can inhibit your ability to get an erection. In order to experience the best results of sildenafil, it is recommended that you limit the amount of alcohol you drink.

Can I take sildenafil with other ED medications?

Sildenafil should not be taken in combination with other erectile dysfunction medications unless specifically advised by a doctor.

Do recreational drugs affect sildenafil?

It can be dangerous to take sildenafil with recreational drugs, including stimulants such as ecstasy or cocaine, hallucinogens such as LSD and former-legal highs such as mephedrone.

Treatment Options

Sildenafil vs Viagra

Sildenafil and Viagra are proven to be as effective as one another in treating erectile dysfunction by the UK medicines regulator. While some men will still prefer branded Viagra, Sildenafil is a significantly better value, effective option for ED.

Alternative treatments

In the UK, most treatments for erectile dysfunction require a prescription, however, Viagra Connect is available over the counter and from our range. Like sildenafil, tadalafil (Cialis) and vardenafil (Levitra) are PDE-5 inhibitors that work by increasing blood flow to the penis in the event of sexual stimulation. Tadalafil (Cialis) lasts significantly longer and can remain effective for 24 to 36 hours. 

Spedra is the newest ED medication and takes as little as 15 minutes to take effect and has a similar duration of action to sildenafil and vardenafil

A common overseas version of sildenafil is Kamagra which is not legal in the UK. It is recommended that you consult a doctor about switching to the legal alternative, Sildenafil.


Is sildenafil safe for long-term use?

Sildenafil is safe for long-term use however the underlying cause of the condition should be addressed if possible. Erectile dysfunction often has a psychological or physical cause, such as anxiety, depression, stress, excess weight, poor diabetes control and continued use of treatments such as sildenafil may mask these issues and prevent the patient from pursuing more effective, long-term help.

Is sildenafil a cure for ED?

Sildenafil will not cure erectile dysfunction, the root cause of which is often physical or psychological. Identifying the root cause of your ED and resolving it if possible is the best way to improve ED long term.

Can women take sildenafil?

There is little evidence to suggest that sildenafil has any effect on female libido or sexual enjoyment and it is not licenced for arousal disorders in women. Speak to your GP about your options for medicines if you are female.

Is it safe to buy sildenafil online?

It is safe to buy sildenafil online from a registered pharmacy such as Dr Felix. It is a prescription-only medication and should not be purchased online through any service that is not registered in the UK.

Can I buy sildenafil without a prescription?

Provided you use a UK registered online service such as Dr Felix that provides a prescription as part of your order, you can buy sildenafil online without a prescription.

How long does sildenafil take to work?

Sildenafil takes 30 to 60 minutes to work on average and therefore it is advised to be taken one hour before sexual activity. It is very important to note that Sildenafil works fastest when taken on an empty stomach. If taken on an empty stomach, it is more likely to take effect in 30 minutes. If taken after a heavy meal, allow at least 60 minutes for the sildenafil tablet to work.

How long does sildenafil last?

Sildenafil typically lasts for 4-6 hours. This does not mean that you will have an erection for this whole time period but rather it will be easier to get and keep one.

Prices from:

Start your consultation now

We’re a fully regulated pharmacy, with qualified doctors and happy customers


Quick and discreet

Very efficient great service have dealt with the them often no problem recommending them looking forward to dealing with them in the future.


What is your gender?


Quick and discreet

Fast and reliable. Delivered well on time. I would recommend Dr Felix to anyone. An Excellent service each and every time. Thank You.