Erectile dysfunction is when you are either:unable to get an erectionunable to keep an erection for long enough to have sexDepending on the cause, you may still be able to get an erection at other times, such as when you wake up.Sometimes you might also have low sex drive (loss of libido).

Sildenafil tablets are used to treat erectile dysfunction in men, by helping you get and maintain an erection.Sildenafil is not only the name of the ED treatment – it's the active ingredient in the medication. It’s also the active ingredient in both Viagra and Viagra Connect.

Sildenafil works by helping to relax the blood vessels in your penis, allowing blood to flow downstairs when you get sexually aroused.  However, sildenafil tablets will only help you get an erection if you are sexually stimulated. You won’t get an erection simply by swallowing the pill.How long does sildenafil take to work? It normally takes between 30 and 60 minutes for sildenafil to work. And while you can take it up to 4 hours before a romantic encounter, it’s actually recommended to take it one hour prior.  But remember – sildenafil won’t get you hard on its own. It only works if you’re also sexually aroused. How long does sildenafil last? Sildenafil normally stays in your system for 4-6 hours. However, the more time that elapses after you’ve taken it, the less effective it becomes.

Sildenafil tablets come in three doses: 25mg, 50mg and 100mg. The 50mg tablet is the recommended starting dose, and therefore the one you’re most likely to be prescribed. If you find the side effects too much, you can ask to go down to the 25mg dose. And if 50mg isn’t working, you could consider increasing your dose to 100mg. However, the 100mg tablet does come with a higher risk of side effects.

4 tablets8 tablets24 tablets64 tablets25mg£4.95£9N/AN/A50mg£4.99£9TBCTBC100mg£6.50£12TBCTBC

Multiple studies report that when taking 50mg sildenafil, 74% of men found it helped them get and maintain an erection. The efficacy of sildenafil tends to rise and fall with the dosage. So 25mg may be less effective than the 50mg tablet, but 100mg may be more effective.

1. Take one sildenafil tablet around one hour before you plan to have sex. 2. Swallow the tablet whole, with some water. 3. Do not take sildenafil more than once a day. Always make sure to read the patient information leaflet before taking a sildenafil tablet for the first time. And do not take sildenafil with grapefruit, as this can make any side effects worse.

Sildenafil may be unsuitable for certain people.You must be at least 18 years old to be prescribed sildenafil.And do not take sildenafil tablets if you are allergic to any of the ingredients listed in the patient information leaflet, or if it is incompatible with any medications you are already on. Avoid taking sildenafil if: you have severe heart problemsyou have severe liver problemsyou have recently had a stroke or heart attackyou have low blood pressureyou have certain, rare inherited eye diseases e.g. retinitis pigmentosayou have ever had a loss of vision due to non-arteritic anterior ischemic optic neuropathy (NAION)And talk to your doctor before requesting or taking this medicine if:you have sickle-cell anaemiayou have leukaemiayou have multiple myelomayou have a deformity of your penis or Peyronie's diseaseyou have problems with your heartyou have a stomach ulcer or a bleeding problem e.g. haemophilia

Like all medicines, sildenafil may cause side effects in some people, but these won’t affect everybody. The most common side effects of sildenafil are: nausea hot flushes indigestion a colour tinge in your vision blurred vision visual disturbances a stuffy nose dizziness For a complete list of side effects, please refer to the patient information leaflet included with your medication.If you experience any side effects not included in the patient information leaflet, you can report them using the MHRA Yellow Card Scheme.

Most men occasionally fail to get or keep an erection.This is usually caused by stress, tiredness or drinking too much alcohol, and it's nothing to worry about.It can also be a side effect of some medicines.If erectile dysfunction happens often, it may be caused by a condition such as:high blood pressure or high cholesteroldiabetesdepression or anxietyhormone problems