Viagra Side Effects and How to Avoid ThemĀ 

Viagra is the brand name for a medicine called sildenafil, used primarily to treat erectile dysfunction (ED). The active ingredient, sildenafil, is also sometimes used to treat pulmonary hypertension in men and women.Ā Ā 

Viagra is an extremely effective medication. When used for ED, it works by increasing the blood flow to your penis to help you get an erection when you’re aroused. It has been found to help around 80% of users get an erection. 

For pulmonary hypertension, sildenafil used at a different dose to erectile disfunction, helps to relax the blood vessels in your lungs and facilitate blood flow around the body. It is the most prescribed medicine in the world for the treatment of pulmonary hypertension.  

However, like any medicine, Viagra can cause some side effects. Let’s discuss what they are and whether you can avoid them.Ā Ā 

Three key takeaways 

  • Viagra is generally a safe medicine to take, but it can cause some side effects which range from mild to severe.Ā 
  • The most common Viagra side effects for men include hot flushes, headaches, diarrhoea, nausea (feeling sick) and indigestion.Ā Ā 
  • If you experience severe side effects (e.g., loss of vision, a prolonged or painful erection, a seizure or fit, or chest pain) you should call 999 or go to A&E.Ā Ā 

Man with erectile dysfunction taking Viagra tablet

Is Viagra safe? 

Viagra is generally safe to take and has been licensed to treat ED in the UK since 1998. However, some people may not be able to use Viagra. You should speak to your doctor or pharmacist before taking sildenafil if you: 

  • have ever had an allergic reaction to sildenafil or any other medicineĀ 
  • are taking medicines called nitrates for chest pain (angina)Ā 
  • have a serious heart or liver conditionĀ 
  • have recently had a stroke, heart attack or a heart problemĀ Ā 
  • have low blood pressure (hypotension)Ā 
  • have a rare inherited eye disease, such as retinitis pigmentosaĀ 
  • have sickle cell anaemia (an abnormality of red blood cells), leukaemia (cancer of blood cells) or multiple myeloma (cancer of bone marrow)Ā 
  • have a deformity of your penis or Peyronie's disease (curved penis)Ā 
  • have a stomach ulcerĀ 
  • have a bleeding problem, like haemophiliaĀ 

Most common side effects of Viagra

Like all medicines, sildenafil can cause side effects, although many people don’t experience any side effects at all. The risk of getting side effects increases with higher doses. As a result, you should not use more medicine than is prescribed or recommended in the packet instructions. 

You also shouldn’t use Viagra alongside other ED medications containing sildenafil, such as Aronix and Liberize.Ā Ā 

More than one in 100 people experience some of the common side effects of Viagra. However, you are less likely to experience these if you are taking Viagra for ED than if you are taking it for pulmonary hypertension, as Viagra for ED only requires short term use.  

Common side effects include:   

  • aching muscles (back, arms and legs)Ā 
  • nosebleedsĀ 
  • diarrhoeaĀ 
  • difficulty breathingĀ 
  • flushing (including hot flushes)Ā 
  • headachesĀ 
  • nausea (feeling sick)Ā 
  • indigestionĀ 
  • pain or tenderness around your eyes and cheekbonesĀ 
  • sneezingĀ 
  • stomach discomfort after eatingĀ 
  • a stuffy or runny noseĀ 

These side effects should not require medical attention and should go away on their own.Ā Ā 

Other side effects of Viagra 

While the above are the most common side effects of Viagra, there are some uncommon, rare and serious side effects you should be aware of.  

Uncommon side effects of Viagra 

These side effects of taking Viagra are slightly less common: 

  • bladder painĀ 
  • a burning feeling in your chest or stomachĀ 
  • burning, crawling, itching, numbness, prickling, "pins and needles", or tingling feelings in your arms, hands, feet, or legsĀ 
  • cloudy or bloody urineĀ 
  • dizzinessĀ 
  • increased urinationĀ 
  • painful urinationĀ 
  • stomach upset and tenderness in your stomach areaĀ 

Rare side effects of Viagra  

Rarely, people can experience:  

  • abnormal dreamsĀ 
  • anxietyĀ 
  • clumsiness or unsteadinessĀ 
  • severe diarrhoeaĀ Ā 
  • difficulty swallowingĀ 
  • ear painĀ 
  • eye painĀ 
  • increased salivaĀ 
  • heightened skin sensitivityĀ 
  • lack of coordinationĀ 
  • loss of bladder control (incontinence)Ā 
  • rectal bleedingĀ 
  • red or irritated tongue or gumsĀ 
  • ringing or buzzing in your earsĀ 
  • sensation of motionĀ Ā 
  • failure to reach orgasmĀ 
  • fatigue (sleepiness)Ā 
  • sores in your mouth and on your lipsĀ 
  • trembling and shakingĀ 
  • worsening asthmaĀ 
  • behaviour changes (acting like you’re drunk)Ā 
  • bleeding in your eyeĀ 
  • blurred visionĀ 
  • double visionĀ 
  • chillsĀ 
  • cold sweatsĀ 
  • confusionĀ 
  • cool and pale skinĀ 
  • sudden loss of hearingĀ 
  • less frequent urinationĀ 
  • difficulty concentratingĀ 
  • dizziness, light headedness or faintingĀ 
  • dry eyesĀ 
  • dry mouthĀ 
  • excessive hungerĀ 
  • fast, irregular, or pounding heartbeatĀ 
  • feeling like something is in your eyeĀ 
  • increased pupil sizeĀ 
  • excessive sweatingĀ 
  • increased thirstĀ 
  • painful, swollen jointsĀ 
  • red, itchy or teary eyesĀ 
  • restless sleepĀ 
  • changes in colour vision (seeing a blue tinge on objects or having difficulty telling the difference between blue and green)Ā 
  • seizuresĀ 
  • sensitivity to light (photophobia)Ā 
  • skin rash, hives, ulcers or itchingĀ 
  • slurred speechĀ 
  • sudden weaknessĀ 
  • swelling of the face, hands, feet, or lower legsĀ 
  • muscle twitchesĀ 

Serious side effects of Viagra  

Less than one in 1,000 people experience serious side effects of Viagra.  

These include: 

  • sudden loss of visionĀ Ā 
  • seizure or fitsĀ Ā 
  • a prolonged or painful erection that lasts more than two hours (priapism)Ā 
  • chest pain (do not take nitrates to treat this)Ā 

It is also possible to have a serious allergic reaction (anaphylaxis) to Viagra. The symptoms of anaphylaxis include: 

  • a swollen throat or tongueĀ 
  • having trouble breathing or breathing very fastĀ 
  • finding it difficult to swallow, feeling tight in your throat or having a hoarse voiceĀ Ā 
  • wheezing, coughing or loud breathingĀ 
  • feeling tired or confusedĀ 
  • feeling faint, dizzy or falling unconsciousĀ 
  • a weak or rapid pulseĀ 
  • nausea, vomiting or diarrhoeaĀ Ā 
  • cold skinĀ 
  • blue, grey or pale skin, lips or tongue (if you have brown or black skin, this may be easier to see on the palms of your hands or soles of your feet)Ā 

You should call 999 (do not drive yourself) or go to A&E if you experience any of these symptoms.  

Can Viagra cause long-term side effects? 

Long-lasting side effects associated with taking sildenafil on a long-term basis are rare. However, if priapism is left untreated, it can lead to permanent erectile dysfunction, so you should not ignore this side effect if you experience it. 

Viagra can also cause permanent vision loss due to a serious eye condition called non-arteritic anterior ischemic optic neuropathy. However, both of these side effects are extremely rare.  

When to go to the doctor for Viagra side effects  

ā€œYou should speak to a doctor or pharmacist for advice if you experience any side effects associated with Viagra. They will be able to advise you on whether you need to stop taking Viagra, change your dosage or are safe to continue taking it.ā€Ā Ā 

Ian Budd, Prescribing Pharmacist at Chemist4UĀ 

However, there are some serious side effects of Viagra that can require emergency treatment. 

How to avoid Viagra side effects  

If you are experiencing side effects from taking Viagra and they are impacting your life, you should speak to your GP or a pharmacist. They may recommend taking a lower dose of the medication or suggest another type of treatment.  

For minor side effects, such as flushing, indigestion, dizziness, or back and muscle pain, there are a few tips that may help you manage these symptoms: 

  • Flushing: you can try to cool down by opening a window, turning on a fan, or having a cold drink. It may also help to lie down and rest. If you are prone to hot flashes while taking Viagra, you should avoid drinking alcohol as this can worsen this symptom.Ā 
  • Indigestion: Try taking Viagra with food, though this may mean it takes longer for the drug to work. You can also try taking antacids to help with this.Ā Ā 
  • Dizziness: Lie down, rest and try to get up slowly as the dizziness passes. If you are prone to dizziness after taking Viagra, you should avoid drinking alcohol and smoking as these can make dizziness worse.Ā Ā 
  • Back or muscle pain: It may help to lie down or do a gentle self-massage. You can also try pain relievers, such as paracetamol and ibuprofen.Ā Ā 

FAQs 

Which form of Viagra has the least side effects? 

Viagra and Viagra Connect side effects are the same, as both products contain the active ingredient sildenafil. The only difference between them is that Viagra is prescription only, whereas you can buy Viagra Connect over the counter.  

Are the side effects of Viagra in older men worse? 

All available evidence so far indicates that Viagra for men side effects do not differ between older and younger men. However, older men do tend to accumulate more sildenafil in their bodies and, as we know, higher doses produce an increased risk of side effects. So, in theory, being older may increase your risk of experiencing side effects.  

Do women experience the side effects of Viagra? 

Viagra increases the blood flow in your body whether you were born male or female. As a result, people born female can also experience many of the side effects of Viagra, such as flushing, headaches and nausea. Viagra is only licenced for the treatment of ED in people born male. Sildenafil should not be taken by people born female, unless it is being used to treat pulmonary hypertension. 

Does drinking alcohol increase the chance of experiencing side effects? 

It’s usually safe to drink a small amount of alcohol on nights you plan to use Viagra. However, excessive drinking can increase your risk of experiencing certain side effects, such as headaches and flushing.  

Does Viagra interact with other medications?  

A number of different medicines can interact with Viagra. If you are taking another medication, you should let your pharmacist or GP know which ones before you start taking Viagra. The most significant medications Viagra interacts with (nitrates and alpha-blockers) can cause a dangerous drop in blood pressure.  

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Ian Budd - Prescribing Pharmacist
Ian Budd , Prescribing Pharmacist on 09 October 2025
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