News item 29/05/2005
Six British men using the impotence drug Viagra have reported experiencing a type of blindness, it has emerged.
The incidents became known after the Food and Drug Administration (FDA) in the US announced it is investigating reports of similar eye problems among users of the drug and its counterpart Cialis.
The FDA has had 42 reports of the blindness - called NAION (non-arteritic anterior ischemic optic neuropathy). Four were among Cialis users and 38 among users of Viagra. It said there is no evidence yet that the drug is to blame for the loss of sight.
NAION can occur in men who are diabetic or have heart disease, the same conditions that can cause impotence and thus lead to Viagra use.
A "thorough review" of possible side-effects was carried out three years ago, after warnings were raised by doctors through the "yellow card" system, the director of the Medicines and Healthcare Products Regulatory Agency (MHRA) said.
The yellow card scheme, introduced in 1964, allows doctors and other health care professionals to alert the MHRA to suspected side-effects linked to drugs.
Dr June Raine said no causal link between Viagra use and eyesight problems has been found in the UK. It is not considered necessary at this stage to change the wording of product information leaflets issued with Viagra, she added.
The issuing of a yellow card does not prove that the drug has caused the problem, only that the doctor suspects there may be a link and believes it would be worth investigating.
Six British men using the impotence drug Viagra have reported experiencing a type of blindness, it has emerged.
The incidents became known after the Food and Drug Administration (FDA) in the US announced it is investigating reports of similar eye problems among users of the drug and its counterpart Cialis.
The FDA has had 42 reports of the blindness - called NAION (non-arteritic anterior ischemic optic neuropathy). Four were among Cialis users and 38 among users of Viagra. It said there is no evidence yet that the drug is to blame for the loss of sight.
NAION can occur in men who are diabetic or have heart disease, the same conditions that can cause impotence and thus lead to Viagra use.
A "thorough review" of possible side-effects was carried out three years ago, after warnings were raised by doctors through the "yellow card" system, the director of the Medicines and Healthcare Products Regulatory Agency (MHRA) said.
The yellow card scheme, introduced in 1964, allows doctors and other health care professionals to alert the MHRA to suspected side-effects linked to drugs.
Dr June Raine said no causal link between Viagra use and eyesight problems has been found in the UK. It is not considered necessary at this stage to change the wording of product information leaflets issued with Viagra, she added.
The issuing of a yellow card does not prove that the drug has caused the problem, only that the doctor suspects there may be a link and believes it would be worth investigating.
