Sildenafil (Viagra) Side Effects: The ultimate guide

Sildenafil (Viagra) Side Effects: The ultimate guide
Medically approved by
Dr Earim Chaudry
Last updated
15th July 2020

Erections aren’t always easy for millions of men in the UK. It’s no big deal. Choose from highly effective, clinically proven solutions.

In 30 seconds…

When you take Viagra, its active ingredient, Sildenafil, gets to work. This increases blood flow to your penis by acting on the enzymes responsible for muscle contraction within the blood vessels. Of course, as with any medication, there can be side effects to Viagra – but these side effects are usually mild.

Mild Viagra side effects can include dizziness and headache, indigestion, and hot flushes. Blurred vision and nasal congestion can also occur. The side effects of Viagra in older men are the same – but are thought to be more likely due to increased chances of other medical conditions.

More serious or long-term side effects of Viagra are very rare, but can potentially include erections that just won’t go away, sensory impairment, and digestive problems. These are more likely to be evoked in patients with pre-existing conditions. If you experience any of these, go and see your doctor.

What Happens When You Take Viagra?

Viagra is the most famous treatment for erectile dysfunction (ED), the reduced ability to achieve and sustain an erection. When you take Viagra, the active ingredient, Sildenafil, begins to work its magic. This drug, like other similar drugs – including Tadalafil and Vardenafil – is what is known as a PDE5 inhibitor: it tackles the enzyme PDE5 which is responsible for muscle contraction in your penis. 

It’s through this process that Viagra enables improved blood-flow to where you need it. Sildenafil widens your blood vessels by blocking the action of the enzyme PDE5, thereby it relaxes the smooth muscle within the vessels supplying the penis, consequently enabling you to get and maintain better erections. The active agent, Sildenafil, is what makes all this happen – and it usually takes about an hour for it to take effect. 

Viagra (Sildenafil)

The little blue pill

It’s the active ingredient in Viagra. MHRA approved and clinically proven to be highly effective by increasing blood flow into the penis.


Best for
One off use
Effective in
8 out of 10 men
Dosage
50 to 100mg

What are the Side Effects of Viagra?

Given that Sildenafil is a medical treatment, there can be side effects. However, these side effects are usually rare, mild, and temporary, and the benefits to you will usually outweigh the risks. 

The most common Viagra side effects are flushing, headaches, indigestion, dizziness, and changes to your vision. Usually, they will pass quickly – and you can help them on their way with simple measures. If you have a headache, drink water. If you are feeling dizzy – which is most common if you get up too quickly – stay still until it passes. 

Don’t drive until your side effects pass – and, if they don’t go away, inform a doctor as soon as you can.

There are some horror stories of Viagra side effects, including erections that just won’t disappear, as well as sudden loss of hearing or sight. These are possible and can be dangerous, but they are very rare. They occur in less than 0.1% of men – and most commonly in heavy smokers or those with heart disease or high blood pressure.

Side Effects of Viagra in Older Men? 

There are no known side effects of Viagra that affect older men specifically. However, it’s an unfortunate fact that older people might be more sensitive to the negative side effects of Sildenafil – particularly older men with pre-existing medical conditions. Always document any medical conditions or other medicines you’ve taken prior to buying and using Viagra – or any erectile dysfunction medication.

Taking Sildenafil with Other Medications

If you are taking medications known as nitrates, which are usually prescribed for chest pain, or guanylate cyclase stimulators for high blood pressure, it is highly advisable that you avoid taking Sildenafil. This combination can result in severe drops in blood pressure – which can be dangerous.

Talk to your doctor before taking Viagra if you have previously had a heart attack or stroke, or if you suffer from unstable angina. It is usually not advised, by the way, to take Viagra if you are using cannabis or other recreational drugs.

How Long do Viagra Side Effects Last?

Viagra side effects do not usually last for very long. The more common side effects, including headaches, dizziness, and a blocked nose, should pass quickly – and headaches can be treated by drinking water and taking over-the-counter painkillers such as paracetamol. 

Remember that the effects of Sildenafil usually last for about four hours. After this, your side effects should have passed. If you still have an erection after this time – and if it is painful – consult a doctor immediately. This might be what is known as priapism and can be damaging for your penis.

Are There Any Long-term Side Effects From Using Viagra?

Whilst most of the Viagra side effects are temporary and mild, long-term side effects are incredibly rare. These include potential problems with the digestive system, with the cardiovascular system, and in your hearing and vision. 

The PDE5 enzymes that Sildenafil tackles are also to be found in the eyes, meaning that, with prolonged use, your vision can become blurred, discoloured, or suffer temporary impairment. Meanwhile, incontinence and difficulties ejaculating have been reported, but these side effects are uncommon. 

Importantly, people who use the drug over long periods of time – and young men in particular – can experience another long-term side effect of Viagra: psychological dependence. When people who don’t have ED use Sildenafil , they can ultimately become reluctant to have sex without it. Only those who need the drug should take it. 

Finally, for those wondering, there is no evidence that the effectiveness of Viagra decreases over time. So, you won’t build up a tolerance to it if you use it a lot. 

Key Takeaways…

Viagra is a clinically approved treatment for ED and it is safe and effective in the vast majority of cases. However, there are side effects of Viagra that you should be aware of before you take it. Always read the accompanying Patient Information Leaflet (PIL) for a more comprehensive overview of the side effects.

In the short term, these can include headaches, dizziness, flush, and a blocked nose. However, the long term side effects of Viagra and Sildenafil – including vision impairment and priapism – are potentially more serious. If in doubt, give us a call – our medical team will gladly guide you.

Erections aren’t always easy for millions of men in the UK. It’s no big deal. Choose from highly effective, clinically proven solutions.

While we've ensured that everything you read on the Health Centre is medically reviewed and approved, information presented here is not intended to be a substitute for professional medical advice, diagnosis, or treatment. It should never be relied upon for specific medical advice. If you have any questions or concerns, please talk to your doctor.

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