Sildenafil Citrate

Viagra (Sildenafil)

You can buy Viagra online from just £19.99 with Superdrug Online Doctor, with discreet delivery straight to your door. All you have to do is complete a short online questionnaire about your health, and our doctors can prescribe Viagra if it is safe and appropriate for you. All orders are delivered in discreet packaging, and our doctors can provide free expert advice if you have any questions about Viagra or Erectile Dysfunction.

Is it safe to buy Viagra online?

Yes, it is safe to buy Viagra online from trusted and regulated websites like Superdrug Online Doctor. Our doctors will only prescribe Viagra if it is safe for you to take, and we guarantee that we are dispensing real medication. However, you should be aware when purchasing Viagra online - Viagra is one of the most counterfeited medicines in the world, and fake Viagra has been known to contain ingredients such as methamphetamine, printer ink, or drywall. If you’re getting medications online in the UK, make sure that the company is registered with the Care Quality Commission (CQC) and the General Pharmaceutical Council (GPhC), who are organisations that make sure that the medication is real and that licensed doctors are prescribing them.

Can I get Viagra over the counter?

As Viagra is a prescription-only medication, you can’t get Viagra over the counter. However, there is a different type of Viagra, called Viagra Connect, that you can get over the counter without a prescription. Read more to find out how to get Viagra over the counter.Viagra is a prescription-only medication that is used to treat erectile dysfunction, and works for around 74% of men who try it. It works by increasing the blood flow to your penis, which makes it easier for you to get and keep an erection. It usually takes 30 to 60 minutes for Viagra to start working after you take it, and the effects last for up to 4 hours.

Why do I need to get a prescription?

Viagra is a prescription-only medication, which means that a doctor has to assess you to make sure it’s safe to take it. This is because it may react with certain medications, or may not be suitable if you have certain conditions. There is a type of Viagra called Viagra Connect which is available without a prescription from a doctor, but you will still need to go through an assessment with a pharmacist before you can get it. There are many different factors that can cause erectile dysfunction, from psychological factors such as stress or anxiety, to physical problems with your circulation or nervous system. Often, there are several factors causing erectile dysfunction, not just a single cause. For more information, read our doctors’ advice on the causes of erectile dysfunction.

  1. Viagra comes in 3 different dosages, 50mg, 25mg, and 100mg. The higher the dosage the more of an effect it will have, but a higher dosage may also increase the chance of side effects. You may want to try different dosages to find which one works best for you. 
  2. Viagra 50mg is the standard starting dose for most people, and is what we recommend if you’ve never tried Viagra before. 50mg is the most popular dosage of Viagra, and is effective for most men who try it.
  3. Viagra 25mg is the lowest dose of Viagra available. It is slightly less effective than Viagra 50mg, but it is also less likely to cause side effects. 25mg might be the best dosage for you if you tried 50mg and it worked for you, but you got side effects that you’d like to avoid. This dosage may also be offered if you are taking other medications to reduce the chance that the medications interact.
  4. Viagra 100mg is the highest dose of Viagra available. It is more effective than lower dosages of Viagra, but is also more likely to cause side effects. 100mg might be the best dosage for you if you tried 50mg and it didn’t work for you, and you didn’t get any side effects.
    Viagra is a type of medication known as a PDE-5 inhibitor, which works by improving the blood flow to your penis when you are aroused. This makes it easier for you to get and keep an erection that’s hard enough to have sex with.

It only works if you’re turned on and will not make you get an erection by itself. It also doesn’t improve low sex drive. Viagra takes about 30 to 60 mins to start working, so it’s recommended you take it 1 hour before you want to have sex. However, the length of time it takes Viagra to work can be affected by factors such as how aroused you are, what food you’ve eaten, and if you’ve drank alcohol.

  • Arousal - Viagra only works if you are aroused, it won’t give you an erection on it’s own. If you are unable to get an erection after taking Viagra, it may be the case that you aren’t sexually stimulated enough to get one.
  • Food - Certain foods, especially heavy or greasy meals, can make it harder for Viagra to be absorbed into your bloodstream. This makes it take longer to start working, and can even make it less effective.
  • Alcohol - Alcohol interacts with Viagra, making it take longer to start working and making it less effective. Drinking too much can also make it harder to get an erection anyway, which makes Viagra less likely to work when you need it to.


Viagra lasts for around 4 to 6 hours after you take it, so you shouldn’t take it early in the day if you’re planning to have sex in the evening. Your age, diet, and health can all impact how long Viagra lasts. See our How Long Does Viagra Last page for more info.

Does Viagra make you last longer in bed?

Viagra can help you to get and maintain an erection, so you can stay harder for longer if you find it difficult to keep an erection. However, Viagra does not delay ejaculation so it will not make you last longer if you feel you are orgasming too quickly. If you are orgasming too quickly, then you may want to try premature ejaculation treatment, which can help you last longer. For more information, you can read our doctors’ advice on how to last longer, and if Viagra can help. Viagra can only make your erection bigger if you are having trouble getting fully erect. Viagra doesn’t increase your maximum erection size. There is no medication that makes your maximum erection size bigger. Only surgery can increase the overall size of the penis.

Before taking Viagra, you may have trouble maintaining an erection during sex, which may result in issues to do with your sex life. Once prescribed, take Viagra up to 4 hours before you want to have sex. For most people, it takes 30 to 60 minutes for Viagra to work, and it can continue to work for around 4 hours. This causes the blood vessels to relax, allowing blood to more easily flow to the penis, which should help you to get and keep an erection more easily. For more information, read our page on what to expect before and after starting Viagra. Viagra is effective for most men, but not all of them. If you are taking 25mg or 50mg of Viagra, and it has not worked on several separate occasions, then you may want to try a higher dose, if approved by your doctor. If you try Viagra 100mg and it does not work for you, then Viagra may not be right for you and you could try another erectile dysfunction medication.

  • To take Viagra, swallow one tablet whole with water or juice around an hour before you want to have sex. You should only take one tablet every 24 hours.
  • For the best results, you should take Viagra on an empty stomach. This doesn’t mean that you shouldn’t eat for the entire day, but you should leave two hours between your last meal and taking Viagra.
  • You should avoid heavy or greasy meals before taking Viagra, as it makes it take longer to start working. You should also avoid drinking alcohol, as it can make Viagra less effective by making it harder for you to get an erection.
  • You should also avoid grapefruit juice, which changes how your body breaks down medicines such as Viagra, which makes it take longer to start working.
  • If you’re nervous about taking Viagra for the first time, you could try taking it on your own to see how it works. This can help you get comfortable with how it feels, and build confidence that it will work for you when you need it.


You should take Viagra at least an hour before you plan to have sex. This gives the medication time to start working, so you’re ready to have sex when you want to. Viagra lasts for up to four hours after taking it, so you’ll still be able to get and keep an erection even if you take it earlier than an hour before. You can take one Viagra tablet every 24 hours. Taking any more than this is unsafe, which could cause side effects or serious health complications, including permanent damage to your penis. You should also not change your dosage of Viagra, so you should not take two 25mg tablets to have a 50mg dose unless advised to do so by a doctor, as this may be unsafe if your doctor has prescribed you a lower dosage. If you take Viagra and do not feel that it is working, you should not take another tablet. It may just be taking a little longer to start working, and even if the medication is not effective it is still inside your body, so taking more could cause complications.

Yes, it is safe to take Viagra for as long as you need it. Studies of long-term Viagra use have shown that it doesn’t cause health problems, and that it stays effective in helping men to get and keep an erection. Drinking alcohol may reduce your ability to get an erection, making Viagra less effective, and can also make the side effects of Viagra worse. While alcohol is often used by some people to overcome nerves and sexual anxiety, drinking can actually make it harder to get an erection - and can make Viagra less effective. Alcohol can also worsen the side effects of Viagra, even when drinking in moderation. Read what our doctors have to say about the risks of taking Viagra with alcohol. Viagra, like most medications, has a shelf life and can become less effective if it’s left unused for too long. You should check the expiry date on your own packet, and should be stored below 30°C and out of direct sunlight.

You should aim to use your medication by the expiration date printed on the box of your medication. If your Viagra is past the expiration date, you should take it to a pharmacy for them to dispose of, and get a new box of Viagra as it may not be safe to take it.

  1. Sildenafil is the generic (unbranded) version of Viagra, which means that it works in the exact same way. It is available in 25mg, 50mg, and 100mg - the same as Viagra. Sildenafil can be made by any pharmaceutical company which means that it is usually available at a lower cost. With Sildenafil, you are getting the same medication but not paying for the brand name.
  2. Viagra Connect is a type of Viagra that works in the exact same way, but it’s only available in a 50mg dose. You don’t need a prescription to get Viagra Connect, so you can get it over the counter in most UK pharmacies after a consultation with the pharmacist. Pharmacists will use the same assessment that we use online to check if it is right for you.
  3. Cialis is an erectile dysfunction treatment that starts working faster than Viagra, and the effects can also last a lot longer - up to 36 hours. Cialis is also available in a daily dosage, called Cialis Daily, which is suitable for people who have frequent or spontaneous sex. The generic version of Cialis is Tadalafil.
  4. Levitra is another erectile dysfunction treatment which works in a similar way to Viagra. Both take up to an hour to start working, and last for up to 6 hours. Levitra may be a better option if you have diabetes, as studies have shown it’s more effective for men with diabetes than Viagra. The generic version of Levitra is Vardenafil.
  5. Spedra is the fastest working erectile dysfunction tablet, helping you get an erection in 15 to 30 minutes. Spedra is less effective than Viagra, but is a good alternative if you have spontaenous sex. There is no generic version of Spedra available in the UK.

For more helpful information on what other options are available to treat erectile dysfunction, read our doctors recommendations on Viagra alternatives. No, you should never combine Viagra with another ED medication. ED medications such as Viagra, Levita, and Cialis all work in the same way, so taking them together could cause serious side effects, or even cause an overdose. Herbal Viagra is a name given to a number of products, such as Horny Goat Weed, that are sold as an alternative to Viagra. However, no herbal treatments are currently recommended or licensed to treat erectile dysfunction, and these products can actually cause more harm than good. Mixing Viagra with herbal supplements may also have unintended interactions which could cause side effects, so let your doctor know if you are taking any herbal supplements before taking Viagra.
There are side effects that can be caused by taking Viagra, these become more likely as the dosage increases. Many people who take Viagra have no side effects.

Common Viagra side effects include:

  1. Headaches
  2. Feeling sick
  3. Dizziness
  4. Indigestion
  5. Nosebleed
  6. Blocked nose
  7. Backache

Uncommon Viagra side effects include:

  1. The common cold
  2. Blurred vision
  3. Rash
  4. Difficulty sleeping
  5. Fever
  6. Trouble breathing
  7. Urinary tract infection

If you get any of the rare side effects, stop taking Viagra and call 999 straight away. Read more on the side effects of Viagra at Superdrug Online Doctor, or the patient leaflet for the medication. There’s no strong evidence to suggest that taking Viagra will prevent you from having a baby in the future. In fact, Viagra is more likely to help you if you are trying for a child, as it enables you to get and keep an erection hard enough for sex. 
Viagra can interact with certain medications and make them less effective, or cause unintended and potentially dangerous side effects. It is important to tell your doctor about any other medication you are taking before you take it.

Some medications that are known to interact with Viagra are:

  • Aspirin
  • Fish oil
  • Ibuprofen
  • Tramadol
  • Adderall


Sildenafil, the active ingredient in Viagra, is sometimes used as a treatment for pulmonary hypertension (high blood pressure in the lungs). This is because sildenafil lowers blood pressure by widening the blood vessels, which is also how it works to treat erectile dysfunction. If you have low blood pressure, or are taking medications to lower your blood pressure, you should speak with a doctor before taking Viagra. Even if you don’t have a pre-existing condition, there are other situations where you shouldn’t take Viagra. You shouldn’t take Viagra if you:

  1. Are taking other ED medications
  2. Have sickle cell anaemia
  3. Have a deformity of your penis
  4. Are taking nitrates for chest pain
  5. Have certain eye conditions, such as non-arteritic anterior ischemic optic neuropathy (NAION)
  6. Read more on when you shouldn’t take Viagra.

No, women can’t take Viagra. It is only licensed for male use in the UK, but in places such as the USA there is “female Viagra” available. In actual fact the term “female Viagra” is misleading, as that other drug works in a completely different way, and is used more to increase sexual desire and satisfaction in women.