Reviewed by Dr Samantha Miller MB ChB
(2017, University of Glasgow)
GMC number: 7561464
Information last reviewed 25/05/2021
Viagra is a treatment for erectile dysfunction (ED) which contains the drug sildenafil. In combination with sexual stimulation, it helps a man to achieve and maintain an erection for long enough to engage in sexual activity.
Viagra contains sildenafil, which belongs to a class of drugs known as PDE-5 inhibitors. These work by relaxing blood vessels and increasing blood flow to the penis. Viagra does not increase sexual desire but works when a man becomes sexually stimulated, enabling him to maintain an erection.
Viagra is used for treating erectile dysfunction in men. The active ingredient in Viagra is sildenafil. Sildenafil, under the brand name Revatio, is also used to treat high blood pressure in the lungs (pulmonary hypertension).
Viagra improves erectile dysfunction in more than two-thirds of men with ED, and up to 84% with higher doses. It is not uncommon to try several different types of ED medication at different doses before finding one that suits you. If you feel that Viagra is not working for you, your doctor can help you find alternatives.
Often, erectile dysfunction has a psychological cause, such as anxiety or depression. In this case, counselling can be an effective treatment. This approach can take time and Viagra is often recommended for use in the short term, although it is important not to allow treatment to mask the problem.
When used correctly, Viagra is a safe and effective treatment for erectile dysfunction.
Dose |
One tablet, taken one hour before sex |
Type of medicine | PDE5 inhibitor |
Mechanism |
Increases blood flow around the penis |
Available Size |
4, 8, 12, 16, 32 or 64 tablets |
Available Strengths |
25mg, 50mg or 100mg |
Active Ingredient |
Sildenafil Citrate |
Price |
From £5.37 per tablet |
Side Effects |
Can include headache, nausea, vomiting, indigestion, facial flushing, hot flush, visual disturbances |
The active ingredient in Viagra is sildenafil citrate.
The inactive ingredients in Viagra are microcrystalline cellulose, calcium hydrogen phosphate (anhydrous), croscarmellose sodium, magnesium stearate, hypromellose, titanium dioxide (E171), lactose monohydrate, triacetin and indigo carmine aluminium lake (E132).
You should aim to take Viagra about an hour before sexual activity. It takes 30–60 minutes to have an effect, typically remaining effective for 4–5 hours, with some studies showing effects for up to 12 hours post-ingestion. Once taken, you can engage in your preferred sexual activity as usual. Viagra, along with arousal and stimulation can enhance your ability to achieve and maintain an erection.
Viagra is a convenient and effective treatment for ED but should not be overused or used recreationally. Viagra is a prescription-only medication and should only be used when prescribed to you personally by a doctor. Purchasing Viagra illegally from an unregistered source is very risky as you can never be sure of what you are taking. Viagra should never be used where it is not necessary, as improper use puts you at risk of increased side effects and dependency.
The recommended starting dose for Viagra is 50mg, no more than once daily. Your doctor will be able to adjust your dose if you feel that it is too strong or too weak. The maximum dose is 100mg per day and increasing the dosage further than this will not increase the effectiveness of Viagra but may result in more side effects.
You can start taking Viagra at any convenient time. You may not experience the effects straight away and it is recommended that you trial Viagra on several occasions over the course of a few weeks to assess its effectiveness.
Always take Viagra as instructed by a doctor or pharmacist, who will also instruct you on your dosage. Swallow one tablet whole with a glass of water approximately one hour before sexual activity. Viagra 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, your doctor may alter your dosage. Do not take Viagra more than once per day, as taking too much will increase the likelihood of experiencing side effects.
Like all medications, Viagra can cause side effects. If you experience any of the following serious side effects, stop taking Viagra and seek medical help immediately:
Headaches are the most common side effect of Viagra and affect more than 1 in 10 people.
Uncommon side effects (affecting up to 1 in 100 people) are:
Rarely (less than 1 in 1,000 people), the following side effects may be experienced:
Do NOT take Viagra if you:
You should inform your doctor and take particular care when taking Viagra if YOU:
Before taking Viagra, tell your doctor or pharmacist if you are taking any other medications, including those purchased over the counter without a prescription.
Do not take Viagra along with:
In particular, speak to your doctor if you take:
You should also be aware that grapefruit and grapefruit juice can interfere with Viagra so you should avoid consuming grapefruit or its juice when taking Viagra. You should also avoid fruits related to grapefruits such as pomelos, tangelos and pink grapefruits etc.
Drinking alcohol can inhibit your ability to get an erection. In order to experience the best effects of Viagra, it is recommended that you limit the amount of alcohol that you drink.
Viagra can cause dizziness and disturbances to vision. If you experience either of these side effects, avoid driving or operating heavy machinery.
Different erectile dysfunction treatments are better suited to different people, and it is not uncommon to try a few different treatments to begin with. If Viagra does not work for you, speak to a doctor about alternative treatments for erectile dysfunction.
Viagra and Viagra Connect contain the same active ingredient, sildenafil. Viagra Connect can be purchased over the counter without a prescription and was approved to reduce the number of men purchasing Viagra from illegal sources online. Viagra Connect works in the same way as Viagra but is only available at a dosage of 50mg. Although it is prescription-free, you should consult a doctor or pharmacist before purchasing Viagra Connect.
Viagra and sildenafil both contain the active ingredient (sildenafil) and they work in exactly the same way. Viagra is the brand name for sildenafil, the generic drug.
Viagra is the most well-known and popular treatment for erectile dysfunction. Since it was first approved in 1998, other ED treatments that work in similar ways have been developed. Like Viagra, Cialis (tadalafil) and Levitra (vardenafil) are also PDE-5 inhibitors that work by increasing blood flow to the penis in the event of sexual stimulation. Cialis has a longer action time and can remain effective for up to 36 hours. The most recent treatment that’s been developed for ED is Spedra (avanafil), which is a fast-acting variant that can take as little as 15 minutes to become effective.
Erectile dysfunction can have both physical and psychological causes. Exercise, eating healthily, maintaining a healthy weight and not smoking can help improve underlying physical causes of ED.
The root cause of erectile dysfunction is often psychological. Finding ways to reduce stress in your life can be extremely beneficial, as can maintaining a healthy lifestyle and exercising regularly. Anxiety may also contribute and can be further exacerbated by difficulties with sexual performance. Being open with your partner about your anxieties can often help you to relax. For advice on dealing with anxiety or depression, speak to a doctor or nurse.
Viagra can be purchased online but only from a registered pharmacy such as Dr Felix. Buying Viagra from unregistered on illegal websites can be dangerous, and you can never be sure what you are buying.
In the UK, Viagra is available on prescription at a range of doses, however a 50mg version of Viagra – Viagra Connect – is available over-the-counter without a prescription.
Viagra is made and sold by Pfizer/UpJohn Ltd but the generic sildenafil has been produced by other companies since the patent expired in 2020.
The best way to make sure your Viagra is genuine is to purchase it on prescription from a registered pharmacy following consultation with a doctor.
Viagra is not a cure for erectile dysfunction, the root cause of which is often psychological. However, it can relieve some of the stress and worry associated with ED in the short term.
While Viagra typically remains effective for 4–5 hours after administration, and up to 12 hours, it only works in combination with sexual stimulation. If a man becomes aroused within this time period, Viagra will help him to achieve and maintain an erection. The erection will still subside in the absence of arousal. A rare side effect of Viagra is prolonged and painful erections (priapism). If this happens, stop taking Viagra and seek medical attention.
Viagra is safe for long-term use, but it is important to be aware that this can lead to psychological dependency. ED often has a psychological cause, such as anxiety, depression or stress, and long-term use of treatments such as Viagra can mask these issues and prevent the user from pursuing long-term, psychological help.
Viagra should not be used by women, and there is little evidence to suggest that it has any effect on female libido or sexual enjoyment, and it is not licensed for this purpose. Sildenafil is used to treat pulmonary hypertension in both men and women.
Viagra can stay in the bloodstream for 12 hours or more and may show up on a drug test. Drug tests tend to test for specific drugs and do not screen for the presence of every medication. Viagra would only show up on a blood test if that test is looking for evidence of Viagra or PDE-5 inhibitors.
Prices from:
Generic Viagra
Generic Cialis
Over the counter treatment
Works in 15-30 minutes
Effective for up to 5 hours
For daily or intermittent use
Sildenafil, Tadalafil, Vardenafil
We’re a fully regulated pharmacy, with qualified doctors and happy customers
Fast and reliable. Delivered well on time. I would recommend Dr Felix to anyone. An Excellent service each and every time. Thank You.
Kevin
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.
Patrick