Viagra, active ingredient Sildenafil has become the foremost erectile drug in the world since it was first launched in 1998; it is used by millions of men from all 

  • digestion
  • a colour tinge to your vision or blurred vision
  • stuffy nose
  • dizziness

There are other side effects which are not common and may only affect 1 in 1000 useds. They include:

  • chest pains – if this happens during or after sex, get into a semi-sitting position and try to relax; do not use nitrates to treat your chest pain.
  • prolonged and sometimes painful erections – if you have an erection that lasts for more than 4 hours, contact a doctor immediately.
  • a sudden decrease or loss of vision.
  • a serious skin reaction – symptoms may include fever, severe peeling and swelling of the skin, blistering of the mouth, genitals and around the eyes.
  • Seizures

Erectile dysfunction medication and pre-existing eye conditions

As we can see from above, there are some common and less common side effects of Sildenafil that affect the eyesight of the user. Sildenafil is also associated with other pre-existing eyes problems

  • NAION – this stands for ‘non-arteric anterior ischaemic optic neuropathy’ which causes the loss of vision in one eye. People at risk from developing this condition may have diabetes, heart disease, history of heart attacks or high blood pressure. These conditions are in themselves risk factors in developing erectile dysfunction and it is likely therefore that these men will try Sildenafil; there have been some men who have developed NAION shortly after taking the medication. If you are at risk of developing NAION then it is important to discuss the risks of taking Sildenafil with your healthcare professional first
  • Retinitis pigmentosa – this is a disease which is hereditary which affects the retina and will gradually result in the sufferer losing their eyesight. It can be caused by the mutation of a gene responsible for the production of phosphodiesterase 6 (PDE-6); this is an enzyme which is vital for healthy vision.

In order to sustain an erection, Sildenafil (a PDE-5 inhibitor) inhibits PDE-5 but can sometimes also inhibit PDE-6. When a person has retinitis pigmentosa they have lower levels of PDE-6 than normal and so if the Sildenafil further inhibits its production, it can be harmful to eyesight. For this reason, before taking any of the PDE-5 inhibitor drugs, vardenafil, Sildenafil, avanafil and tadalafil, it is extremely important that you speak to your doctor if you are suffering from retinitis pigmentosa, if you are a carrier of RP or if you have a family history of the disease over the world.

Sildenafil belongs to a group of medicines called phosphodiesterase 5 (PDE-5) inhibitors. It works if you have erection problems by temporarily increasing blood flow to the penis when you get sexually excited.

Side effects of Sildenafil

There are a number of side effects which are commonly experienced. They include:

  • headaches
  • feeling sick
  • hot flushes, including facial flushing
  • Indigestion
  • a colour tinge to your vision or blurred vision
  • stuffy nose
  • dizziness

Further studies

There have been some observations made by an eye specialist in Turkey which may suggest that eye disturbances such as dilated pupils, blurred vision, light sensitivity and ‘color’ vision can last longer than the previously reported 5 hours, sometimes lasting as long as three weeks. However, on closer inspection, some of the Sildenafil users had not been prescribed the drug and had taken the highest dose of 100mg so any observations can only be described as subjective.

A study related to the effects of taking Sildenafil on mice

As mentioned above, temporary visual disturbances have been reported by some men who took Sildenafil. Other research in humans who took at least double the maximum recommended dose of Sildenafil showed that at least 50% had temporary visual disturbance.

There has been another study carried out in Australia which was funded by the National Health and Medical Research Council of Australia. It was an animal study carried out in mice and they were investigating the effects of taking Sildenafil on the retinas of the mice. Some of the mice had previously been genetically engineered to make them carriers of retinitis pigmentosa.

When dosed with Sildenafil, the visual disturbance experienced by the normal mice resolved itself within 48 hours whereas in the mice carrying RP, it took two weeks for them to return to normal.

It was concluded that Sildenafil had a more pronounced side effect on the mice who were carriers of retinitis pigmentosa then the normal mice.

Conclusion

Although it was shown that the genetically engineered mice were more susceptible to the visual disturbances brought about by taking Sildenafil than the normal mice, the effects were reversible in all cases and so did not suggest in any way that any permanent damage was caused. It is also noteworthy that the dose level of the drug that was administered to the mice was five times the maximum dose that a man would take and so it was not known how the results would have turned out had they used the normal dose.

However, studies would need to be carried out over a longer period of time to determine if there would be any long terms effects of retinal damage or permanent visual changes.