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Viagra/Sildenafil

(generic Viagra)
Oral medication

Viagra/sildenafil is a prescription treatment for men with ED (erectile dysfunction), a condition that affects your ability to get or keep an erection. It is a phosphodiesterase 5 type inhibitor (PDE5), which makes it from the same family of drugs as other well know ED medicines such as Cialis/tadalafil. Viagra has been available in the UK as an ED treatment since 2003 and generic sildenafil since 2013. Both medicines are available in 3 different strengths; 25mg, 50mg and 100mg tablets.

Medication effect duration

Viagra/sildenafil can take between 30 to 60 minutes to take effect and should last no longer than four hours. This doesn’t mean that you will have an erection that lasts 4 hours; Viagra/sildenafil will only work when you are sexually stimulated.

 Nutrition information for medication

It is best to take Viagra/sildenafil on an empty stomach or after a low-fat meal because fatty food has been shown to reduce the rate of absorption and strength3,4. What you drink can also affect your performance, so avoid excessive alcohol and avoid grapefruit juice which may possibly affect the absorption of Viagra/sildenafil.

How does Viagra/Sildenafil work?

When you are aroused your tissues release a chemical called nitric oxide (NO), this, in turn, causes the release of a second chemical called cyclic guanosine monophosphate (cGMP). cGMP causes the muscles at the sides of your penis to relax, allowing blood to rush in. The veins that drain the blood from your penis also get compressed, trapping the increased blood in your penis, resulting in an erection.

An enzyme called phosphodiesterase-5 (PDE5) breaks down the cGMP and your penis returns to its original state. Viagra/sildenafil is a PDE5 inhibitor, meaning it blocks the action of PDE5. As your levels of cGMP remain high, the muscles at the side of your penis relax, more blood rushes in and you can achieve a firmer and longer lasting erection. It is important to remember that Viagra/sildenafil only exerts its action when you are sexually aroused. It does not increase your sexual desire, and it will not resolve any underlying physical causes of your ED.

How long does Viagra/Sildenafil take to work?

Viagra/Sildenafil can take between 30 to 60 minutes to take effect and should last no longer than four hours. The time it takes to work is different for each man, but if taken with food it can be a slower effect, so it’s best to take on an empty stomach or after a low-fat meal3,4. Viagra/Sildenafil only works when you are sexually stimulated.

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How do I take Viagra/Sildenafil?

The recommended starting dose of Viagra/Sildenafil is 50mg, but it is also available in 25mg and 100mg doses, so your treatment can be tailored to suit you.

You take one tablet with a glass of water about 60 minutes before you anticipate you will have sexual activity. With sexual stimulation, you may achieve an erection anywhere from 30 minutes up to four hours after taking a treatment of Viagra/Sildenafil.

If I take more tablets, do I get a better effect?

You must not take more than 1 tablet a day or exceed the dose prescribed for you. If you feel that your dose is not appropriate, that the effects of the medication are too much, or not enough, your doctor can alter your dose.

If you do take more than the recommended dose your risk of side effects, including serious ones, like low blood pressure or an erection that wouldn’t go away even after 4 hours, dramatically increases. If you do experience any side effects, particularly serious side effects, you should seek medical attention immediately.

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Is it safe to buy Viagra/Sildenafil online?

While many online retailers claim to supply genuine medicines, they may be unregulated, provided without a genuine doctor consultation and potentially very dangerous. You can rest assured, PrivateDoc is a fully registered digital health service. We have UK registered doctors that review and assess every consultation. All the medicines we supply are 100% genuine and fully regulated by the Medicines and Healthcare products Regulatory Agency (MHRA).

Special considerations when taking Viagra/Sildenafil

Viagra/sildenafil cannot be used:

  • with any other oral or local treatments for erectile dysfunction
  • with treatments for pulmonary arterial hypertension (PAH) containing sildenafil or any other PDE5 inhibitors
  • if you do not have erectile dysfunction
  • if you are a woman
  • if you are under the age of 18
  • if you are allergic to sildenafil or any of the other ingredients in this medicine
  • if you are taking medicines called nitrates, the combination may lead to a dangerous fall in your blood pressure. Tell your doctor if you are taking any of these medicines which are often given for relief of angina pectoris (or “chest pain”). If you are not certain, ask your doctor or pharmacist
  • if you are using any of the medicines known as nitric oxide donors such as amyl nitrite (“poppers”), the combination may also lead to a dangerous fall in your blood pressure
  • if you are taking riociguat. This drug is used to treat pulmonary arterial hypertension (i.e. high blood pressure in the lungs) and chronic thromboembolic pulmonary hypertension (i.e. high blood pressure in the lungs secondary to blood clots). PDE5 inhibitors, such as Viagra/sildenafil have been shown to increase the hypotensive effects of this medicine. If you are taking riociguat or are unsure tell your doctor
  • if you have a severe heart or liver problem
  • if you have recently had a stroke or a heart attack, or if you have low blood pressure
  • if you have certain rare inherited eye diseases (such as retinitis pigmentosa)
  • if you have ever had loss of vision due to non-arteritic anterior ischaemic optic neuropathy (NAION)

Please tell your doctor if you are using, have recently used or might use any other medicines, including medicines obtained without a prescription. Some medicines may cause problems, especially these:

  • Nitrates, medicines for angina, or nitric oxide donors, such as amyl nitrite. Taking these medicines with Viagra/sildenafil could seriously affect your blood pressure. Talk to a doctor without taking Viagra/sildenafil
  • Medicine for the treatment of arrhythmias, such as quinidine, procainamide, amiodarone or sotalol
  • Ritonavir or indinavir, medicines for HIV. Talk to a doctor without taking Viagra/sildenafil
  • Ketoconazole or itraconazole, anti-fungal medicines
  • Erythromycin, or clarithromycin, macrolide antibiotics
  • Alpha-blockers, a type of medicine used to treat high blood pressure and enlargement of the prostate (as benign prostatic hyperplasia)
  • Riociguat

Your doctor must take special care before starting you on Viagra/Sildenafil if you:

  • have sickle cell anaemia (an abnormality of red blood cells), leukaemia (cancer of blood cells), multiple myeloma (cancer of bone marrow)
  • have a deformity of your penis or Peyronie’s Disease
  • have problems with your heart (your doctor should carefully check whether your heart can take the additional strain of having sex)
  • currently have a stomach ulcer or a bleeding problem (such as haemophilia)
  • experience sudden decrease or loss of vision (stop taking Viagra/Sildenafil and contact your doctor immediately)
  • have kidney or liver problems (your doctor may decide on a lower dose for you)
  • are taking medicines known as protease inhibitors, such as for the treatment of HIV, your doctor may start you on the lowest dose (25mg) of Viagra/Sildenafil

Other considerations:

  • You can take Viagra/Sildenafil with or without food, but preferably not after a heavy or high-fat meal as this may delay the effect
  • Alcoholic drinks can make erection difficulties worse
  • Viagra/Sildenafil might make some people feel dizzy or affect their vision. If you feel dizzy or if your vision is affected, after taking Viagra/Sildenafil, don’t drive or operate any tools or machines
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What are the side effects associated with Viagra/Sildenafil?

Like all medicines, this medicine can cause side effects, although not everybody gets them. Most of the effects are mild or moderate.

Very common side effects of treatment (may affect more than 1 in 10 users)

  • Headache

Common (may affect up to 1 in 10 users)

  • Headache
  • Nausea
  • Facial flushing
  • Hot flush (symptoms include a sudden feeling of heat in your upper body)
  • Indigestion
  • Colour tinge to vision
  • Blurred vision
  • Visual disturbance
  • Stuffy nose
  • Dizziness

Uncommon side effects (may affect 1 in 100 users)

  • Vomiting
  • Skin rash
  • Eye irritation
  • Bloodshot eyes/red eyes
  • Eye pain
  • Seeing flashes of light
  • Visual brightness
  • Light sensitivity
  • Watery eyes
  • Pounding heartbeat
  • Rapid heartbeat
  • High blood pressure
  • Low blood pressure
  • Muscle pain
  • Feeling sleepy
  • Reduced sense of touch
  • Vertigo
  • Ringing in the ears
  • Dry mouth
  • Blocked or stuffy sinuses
  • Inflammation of the lining of the nose (symptoms include runny nose, sneezing and stuffy nose)
  • Upper abdominal pain
  • Gastro-oesophageal reflux disease (symptoms include heartburn)
  • Presence of blood in urine
  • Pain in the arms or legs
  • Nosebleed
  • Feeling hot
  • Feeling tired

Rare side effects (may affect 1 in 1,000 users)

  • Fainting
  • Stroke
  • Heart attack
  • Irregular heartbeat
  • Temporary decreased blood flow to parts of the brain
  • Feeling of tightening of the throat
  • Numb mouth
  • Bleeding at the back of the eye
  • Double vision
  • Reduced sharpness of vision,
  • Abnormal sensation in the eye
  • Swelling of the eye or eyelid
  • Small particles or spots in your vision
  • Seeing halos around lights,
  • Dilation of the pupil of the eye
  • Discolouration of the white of the eye
  • Penile bleeding
  • Presence of blood in semen
  • Dry nose
  • Swelling of the inside of the nose
  • Feeling irritable
  • Sudden decrease or loss of hearing

There are further very rare side effects that occasionally people can experience when taking Viagra/sildenafil, for complete details about all side effects always read the Patient Information Leaflet.