Viagra (sildenafil)
Go to
Medically reviewed by
Dr Daniel Atkinson
GP Clinical Lead
on August 02, 2022.
Meet Daniel  
Was this article useful?
1 people found this helpful

What side effects can Viagra cause?

The list of side effects linked to the Viagra pill is long and may look a little overwhelming when you first glance at it. We’re here to guide you through so that you feel confident in your decision to tackle your ED with Viagra.

So, if you’re wondering what are the side effects of sildenafil for ED, then we’ll get right to it.

Viagra contains the active ingredient sildenafil citrate, it is a PDE5 inhibitor. This group of medications have been linked to side effects on blood pressure.

A slight change in blood pressure, whether it be lower or higher, is not usually something to be worried about. Provided that your blood pressure returns to normal once the medication has left your system.

However, some men taking sildenafil may already have low blood pressure or be using blood pressure regulating medication. This is when things could get a little complicated and that’s why it’s very important to tell the prescriber what medication you’re taking and what’s going on with your health.

  • Common side effects

  • Uncommon side effects

  • Rare side effects

Common side effects may affect up to 1 in 10 people. 

  • Nausea (feeling sick), 
  • Facial flushing (where your face turns red), 
  • Hot flush (a sudden feeling of heat in your upper body), 
  • Indigestion (this could feel like heartburn or bloating), 
  • Colour change to vision, 
  • Blurred vision, 
  • Visual disturbance, 
  • Stuffy nose 
  • and dizziness.

Uncommon side effects may affect up to 1 in 100 people. 

  • 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 (tinnitus), 
  • 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), 
  • Blood in urine,
  • Pain in the arms or legs, 
  • Nosebleed, 
  • Feeling hot 
  • and feeling tired.

Rare side effects may affect up to 1 in 1,000 people. 

  • 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
  • and sudden decrease or loss of hearing. 

What to do about a Viagra headache

Getting a headache when you take Viagra is a very common side effect. This means that it can affect more than one in ten people. For some people their headache symptoms may be mild and therefore tolerable and so they can continue to take their medication. 

If you notice headache symptoms, you can try to counter them by drinking plenty of water before and after you take your Viagra pill.  

Can Viagra cause a heart attack?

Viagra should never be taken alongside nitrates, such as Glyceryl Trinitrate spray (GTN) or Isosorbide Mononitrate, as it can result in a significant hypotensive event or a heart attack. Anyone who is taking nitrates should be made aware of the very dangerous and life threatening effect they could have if mixed with sildenafil.

If you use Viagra and experience chest pain, during or after having sex, you should seek urgent medical attention or dial 999.

Other Viagra side effects that may be serious

Let’s take a look at some other serious side effects:

  • Allergic reactions. This could cause symptoms of wheezing; dizziness; swollen face, eyelids, lips or throat and breathlessness. Anaphylaxis or severe allergic reactions need immediate medical attention. If you have known allergies then you should inform the prescriber and study the ingredient list.
  • Priapism or a prolonged erection can also be dangerous. If you have a painful erection or one that lasts for longer than four hours then you need to go to hospital.

Side effects Viagra

Are there any long term side effects of Viagra?

In most cases any side effects that occur when taking Viagra will ease off once the medication leaves your system. However, some of the more serious and rare sildenafil side effects can have long term implications. 

For example, priapism can permanently damage cells in the penis if it is not treated swiftly. This is why you should attend A+E if you have an erection for longer than four hours. 

Also, men who have inherited eye conditions, such as retinitis pigmentosa, should not take Viagra as it can lead to further permanent vision problems. 

Can my partner get side effects from Viagra?

It’s highly unlikely that your partner will experience side effects if you’re taking Viagra. 

If you have unprotected intercourse with a female partner then they could, of course, become pregnant. There have been studies looking at the impact of Viagra on male fertility, one study concluded that sildenafil did not impact sperm function or quality.

If you’re taking Viagra and have concerns about fertility, you should speak to your doctor.

Should I see a doctor about Sildenafil side effects?

It’s good practice to let your doctor, or the prescriber, know if you experience any side effects when taking a medication. This means that your experience of Viagra symptoms can be recorded and reported to the yellow card scheme. 

Your doctor can talk through the symptoms you’re experiencing and check whether you’re comfortable to continue with your prescription or whether any changes should be made. 

In some cases, the Viagra dosage can be lowered to try and reduce side effects. 

What Viagra side effects you need to go to hospital with

You should go to hospital if you develop chest pain, changes in heartbeat, vision problems or a prolonged erection. Don’t take any more Viagra and don’t take part in sex. You should immediately make your way to a hospital. 

Remember to only take Viagra or Viagra Connect as your clinician advises. If you have any questions while you're taking it, just log into your account and send us a message.

Can I lower my risk of side effects on Viagra?

If you’re concerned about potential side effects when taking Viagra, there are some steps you can take to keep your risk as low as possible. To do this, you need to disclose your past medical history to the prescriber, including any health conditions and any medication you are taking or have recently taken. 

It’s also important to follow the medication instructions closely and to familiarise yourself with the patient information leaflet. 

If your initial Viagra dosage causes side effects, then your doctor may consider reducing the dosage. A lower dosage means less of the active ingredient and thus a reduced chance of developing side effects. The lower dose is less potent but can still work effectively for a lot of men. 

If side effects are causing you a problem then it is definitely worth exploring the lower dose Viagra, but you need to speak to your doctor before doing so. 

Reference Popover #ref1
Reference Popover #ref2
This page was medically reviewed by Dr Daniel Atkinson, GP Clinical Lead on August 02, 2022. Next review due on August 01, 2024.

How we source info.

When we present you with stats, data, opinion or a consensus, we’ll tell you where this came from. And we’ll only present data as clinically reliable if it’s come from a reputable source, such as a state or government-funded health body, a peer-reviewed medical journal, or a recognised analytics or data body. Read more in our editorial policy.

What did you like about it?

What didn't you like about it?

Suggest a treatment

If there’s a particular treatment or condition you’re looking for, tell us and we’ll look into it for you.

We may email you about the problem, but you can opt out of these communications any time you like.

Ask or suggest something.

Submit your question here, or tell us if you’ve found an issue on our site.

We may email you about your query, but you can opt out of these communications any time you like.

Our average rating based on 3204 reviews.

Tell us about a problem

I accept the terms of use.
We may email you about the problem, but you can opt out of these communications any time you like.

We’ll get back to you very soon. We aim to respond to all queries in one working day.

You’re signed up to our newsletter. Keep an eye on your inbox for our latest update.


Sign up to our newsletter for all the latest on and more.

By clicking 'Subscribe now' you're agreeing to our Privacy Policy.