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Medically reviewed by
Mr Craig Marsh
Specialist Pharmacist Prescriber (UK)
on August 02, 2022.
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What side effects can Viagra cause?

The list of side effects linked to the Viagra pill is long and may look a little overwhelming at first. 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 the side effects of sildenafil for ED are, then we’ll get right to it.

Viagra contains the active ingredient sildenafil citrate, which is a PDE5 inhibitor. This group of medications has been linked to side effects that can affect blood pressure.

A slight rise or fall in blood pressure is not usually something to worry about, as long as your blood pressure returns to normal after the drug has worn off (normally after four hours).

However, some men taking sildenafil may already have low blood pressure, or be using blood pressure regulating medication. This is where 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 911.

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.

Are there any long term side effects of Viagra?

In most cases, any side effects that can occur when you take Viagra or Sildenafil will ease off once the medication is out of your system. But some of the more serious (and rare) sildenafil side effects can have longer-term implications.

For example: priapism can permanently damage cells in the penis if it isn’t treated by a medical professional swiftly. So if you find yourself with an erection that lasts for longer than four hours, get yourself to a hospital urgently.

Also, men who have genetic eye conditions like retinitis pigmentosa should also avoid Viagra, as it can permanently worsen their visual problems.

Can my partner get side effects from Viagra?

It’s very unlikely your partner will experience side effects if you’re taking the Sildenafil pill.

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.

You can always talk to your doctor or pharmacist if you have concerns about Viagra and fertility.

Can my partner get side effects from Viagra?

Viagra carries virtually no risk to those who don’t take it, including your sexual partners. It’s very unlikely your partner will experience side effects if you’re taking the Sildenafil pill.

On the subject of partners and pregnancy, 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 .

You can always talk to your doctor or pharmacist if you have concerns about Viagra and fertility.

Should I see a doctor about Sildenafil side effects?

It’s a good idea to let your 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 HPFB.

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, your Viagra dosage can be lowered to try and reduce side effects. (Sometimes it’s just a case of striking the right balance.)

What Viagra side effects you need to go to a hospital with

What Viagra side effects you need to go to a hospital with

If you develop chest pain, heartbeat changes, visual problems or a prolonged erection, go to the hospital right away. Don’t take any more Viagra and avoid doing anything physically exertive (which includes having sex).

Can I lower my risk of side effects on Viagra?

There are also some steps you can take to keep your risk of Viagra side effects as low as possible. Make sure you’re open and honest about your medical history when you talk to a prescriber, especially in relation to health conditions and any medication you take, or have taken.

We know it’s on the hefty side, but read the patient information leaflet. Familiarizing yourself with the instructions, side effects and what to do if taking Viagra doesn’t go exactly to plan can be helpful.

If you get side effects while taking Viagra or Sildenafil, make sure you let your doctor know. They may prefer to keep a closer eye on your use or lower the dose. Doing this means the overall amount of active ingredient you take is reduced, but so too is the risk of side effects. (Most of the time, it should still work just as well.)

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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 recognized analytics or data body. Read more in our editorial policy.

This page was medically reviewed by Mr Craig Marsh, Specialist Pharmacist Prescriber (UK) on August 02, 2022. Next review due on August 02, 2024.

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