Sildenafil works when taken within 1 hour of sex and is an effective treatment for men with erectile dysfunction.(42)
Sildenafil helps treat erectile dysfunction and is manufactured by Milpharm Limited.
Sildenafil is also known by the brand name Viagra. Now you can get generic (no brand) sildenafil tablets that work exactly the same way. Sildenafil is available in 25mg, 50mg and 100mg tablets.
Order sildenafil from Asda Online Doctor by ZAVA today. Our questionnaire is quick and easy to fill out online. Then one of our doctors will check if sildenafil is right for you. Choose delivery to your home address or collection from an Asda Pharmacy.
4 tablet(s) - £14.00
8 tablet(s) - £18.00
12 tablet(s) - £35.00
16 tablet(s) - £41.00
28 tablet(s) - £65.00
4 tablet(s) - £14.50
8 tablet(s) - £22.00
12 tablet(s) - £38.00
16 tablet(s) - £43.00
28 tablet(s) - £70.00
4 tablet(s) - £20.00
8 tablet(s) - £30.00
12 tablet(s) - £50.00
16 tablet(s) - £55.00
28 tablet(s) - £90.00
Sildenafil is a medicine used to treat erectile dysfunction (ED) or impotence in adult men. You can use sildenafil to help to get and keep an erection.
Sildenafil is a PDE5 inhibitor (phosphodiesterase type 5 inhibitor). You can buy sildenafil over the counter at an Asda Pharmacy under the brand name Viagra Connect.
How does sildenafil work?
Sildenafil relaxes your blood vessels which allows more blood to flow into your penis. This blood flow helps you keep your erection.
You should take sildenafil 30 minutes to 1 hour before you want to have sex. Sildenafil will only work if you are sexually aroused. You should only take 1 sildenafil tablet per 24 hours.
Can you take sildenafil with food or drink?
You can take sildenafil with or without food. Keep in mind that a heavy meal can slow down how fast sildenafil will work.
You should not drink a large amount of alcohol before you take sildenafil, as this can make it difficult for you to maintain an erection.
If you are unable to get an erection or keep an erection long enough with sildenafil, contact your doctor.
Sildenafil is available in 25mg, 50mg, and 100mg dosage strengths.
- The lowest dose of sildenafil is 25mg. This might be used if you have any other medical conditions or take any medicines that cause low blood pressure, or if you have had any side effects when using the standard 50mg dose.
- The standard dose for sildenafil is 50mg. You will be prescribed 50mg if you have no medical conditions, or if you have tried the 25mg dose and it was not effective.
- The highest dose for sildenafil is 100mg. This might be used if the standard 50mg dose does not work for you, as long as you did not have any side effects.
You can use 1 sildenafil tablet once a day. Even if you have been prescribed the lowest dose of 25mg, taking more than you need will not make it work faster.
The maximum dose of sildenafil is 100mg. If you take a dose higher than this, it will not make it more effective. You are more likely to have side effects if you take more than 100mg of sildenafil and may need to see an emergency doctor.
If you have taken more sildenafil tablets than advised, contact your doctor immediately. If your erection lasts longer than 4 hours (also called priapism), call 999.
There are some times when you should not use sildenafil, for example, if you:
- do not have erectile dysfunction
- are taking other treatments for erectile dysfunction, such as Cialis (tadalafil) or Levitra (vardenafil)
- have been told by a doctor not to have sex
- are a woman
- are under 18 years old
- take nitric oxide donors or ‘poppers’
- have an allergy to any of the ingredients in sildenafil
- take medicines called nitrates to treat chest pain or heart problems like angina
- take treatment for pulmonary arterial hypertension such as riociguat
- have low blood pressure
- have recently had a heart attack or a stroke
- have an inherited eye disease, such as retinitis pigmentosa
- have ever had loss of vision because of non-arteritic anterior ischaemic neuropathy (NAION)
- have severe heart disease
- have severe liver disease
You should not use sildenafil without speaking to your doctor first if you have:
- sickle cell anaemia,
- leukaemia (blood cancer)
- multiple myeloma (bone cancer)
- any deformity of the penis or Peyronie’s Disease
- a current stomach ulcer
- a bleeding disorder, such as haemophilia
- any heart problems where your heart might not be able to take extra stress
If you are unsure about anything, speak to your doctor or pharmacist. You can also message our doctors through your patient account.
You might get side effects when you take sildenafil. These side effects usually last for a short period of time. You can speak to your doctor at any time for advice on what to do.
Common side effects of sildenafil:
- facial flushing
- increase in body temperature (hot flush)
- blurred vision
- stuffy nose
Less common side effects of sildenafil:
- eye irritation
- bloodshot or red eyes
- chest pain
- change in blood pressure
- allergic reaction
- skin rash
- dry mouth
- blood in the urine
- nose bleed
- feeling tired or hot
- changes in vision
- hearing loss
You can read the patient information leaflet inside your pack of sildenafil for more details.
The following are serious, but rare side effects. If you notice any of these, you or your partner should call 999 so you get medical attention urgently:
- an allergic reaction, like wheezing, difficulty breathing, swelling of the face, lips or throat
- chest pain: if this happens, do not use nitrate medications (given for angina)
- a prolonged or painful erection lasting more than 4 hours
- a sudden loss of vision
- seizures or fits
You should watch out for any dizziness or blurry vision after you take sildenafil. If you experience this, you should not drive or operate machinery.
Sildenafil tablets can interact with other medicines. These drug interactions affect how well sildenafil works or how the other medicines work.
Speak to a healthcare professional, such as your doctor or pharmacist, if you are taking any of the following:
- angina or chest pain treatment called nitrates, such as or glyceryl trinitrate (GTN) or isosorbide mononitrate
- HIV treatment, such as protease inhibitors
- alpha-blockers for high blood pressure, such as doxazosin or alfuzosin
- recreational drugs that affect your blood pressure, such as ‘poppers’
- certain antibiotics, such as erythromycin
You can take sildenafil with or without food. It might take a longer time for sildenafil to work if you have it with a large, fatty, greasy or oily meal.
You should avoid drinking a large amount of alcohol before you take sildenafil, as this can make it difficult for you to maintain an erection.
You might find that you lose an erection every so often, but normally it’s nothing to worry about. If it keeps happening, you could have erectile dysfunction (ED). This means you find it difficult to get and maintain an erection, even when you are sexually aroused.
Erectile dysfunction can occur for a variety of reasons, like:
- if you have a condition that affects the blood vessels in your body, like severe diabetes
- a side effect of certain medications such as antidepressants
- using recreational drugs (like ‘poppers’)
- drinking more than 14 units of alcohol per week
- lifestyle factors such as smoking or obesity
If you think you have erectile dysfunction, speak to your doctor to discuss the best solution.
Which active ingredients does it contain?
The active ingredient in sildenafil tablets is sildenafil citrate (25mg, 50mg or 100mg).
The other ingredients in sildenafil tablets are calcium hydrogen phosphate anhydrous, cellulose microcrystalline, croscarmellose sodium, silica colloidal anhydrous, magnesium stearate, lactose monohydrate, hypromellose 15cP, titanium dioxide (E171), triacetin.
If you have an allergy or hypersensitivity to any of these ingredients please speak to your doctor for advice before taking sildenafil.
Check the patient information leaflet for the most up to date details on the ingredients of generic sildenafil tablets.
How should sildenafil be disposed of?
If you want to dispose of your sildenafil tablets, take them to your local pharmacy. Do not throw away your sildenafil tablets in the bin or down the drain at home.
How should sildenafil be stored?
You should store sildenafil in its original packaging, below 30°C and away from sunlight and moisture. Keep sildenafil away from children or pets.
In which pack sizes is sildenafil available?
Sildenafil 25mg is available in pack sizes of 2, 4, 8, 12, and 24 tablets.
Sildenafil 50mg or sildenafil 100mg are available in pack sizes of 1, 2, 4, 8, 12, and 24 tablets.
Information on the manufacturer
Sildenafil is manufactured by Milpharm Limited and APL Swift Services (Malta) Limited, HF26, Hal Far Industrial Estate, Hal Far, Birzebbugia, BBG 3000, Malta.
Sildenafil, Patient Information Leaflet, EMC [accessed August 2021]
Sildenafil, Summary of Product Characteristics, EMC [accessed August 2021]
Erectile dysfunction, NICE/BNF [accessed August 2021]
Sildenafil (Viagra), NHS [accessed August 2021]
Sildenafil, NICE/BNF [accessed August 2021]
(Reviews are for ZAVA UK)
Asda Online Doctor by ZAVA offers a convenient and discreet service to help men improve their erectile dysfunction. There are a number of treatments you can consider. Continue to our erectile dysfunction service page to learn about the treatment options available.