Erectile Dysfunction Drug Sildenafil Made a Dozen Men Have 'Intense' Blue-colored Vision

More than a dozen men have experienced eye problems—such as their vision going blue—for over a day after taking the erectile dysfunction drug sildenafil, according to a patient case review. This is the core ingredient in Viagra but the study did not indicate that the men were specifically given Viagra.

The men, aged between 38 and 57 years old, visited a clinic in Turkey between August 2017 and March 2019, complaining of eye problems within 48 hours of taking the drug.

According to a case series published in the journal Frontiers in Neurology, nine of the men suffered from sensitivity to light, and 13 saw changes to how they perceived color, including 12 who had "very intensely" blue-colored vision with red-green color blindness.

Of the total, nine had blurred vision; three problems with depth perception; six had disrupted sensitivity to contrast, and eight had abnormally dilated pupils. Almost all of the men who became sensitive to light also had problems seeing color.

The men were healthy and had taken 100 milligrams of sildenafil for the first time without prescriptions from a doctor. Their symptoms lasted more than 24 hours, but were all resolved within 21 days.

Dr. Cüneyt Karaarslan of the Dünyagöz Adana hospital in Turkey, who helped to treat the men and authored the paper, wrote that the patients may have experienced eye problems because their bodies were unable to process the drug.

Karaarslan pointed out the men had taken the maximum recommended dose of sildenafil to treat erectile dysfunction. However, those trying the drug for the first time are advised to consume 50mg, and increase the dose by 25mg up to 100 mg depending on their reaction. "Sildenafil is considered to be generally safe," Karaarslan wrote.

Sildenafil works to treat erectile problems by increasing the blood flow to the penis, and takes between 30 and 60 minutes to work. The drug has a half-life of between three to five hours. The most common side effects include headaches, nausea, hot flushes and dizziness. Less than 1 in 1,000 people experience chest pains, prolonged and or painful erections, vision loss, severe skin reactions or seizures.

The medication is also sold under the brand name Revatio as a treatment for pulmonary hypertension, with most users taking 20mg three times a day.

Karaarslan said in a statement: "Many men use non-prescription performance-enhancing drugs to help with sexual anxiety and erectile dysfunction.

"For the vast majority of men, any side-effects will be temporary and mild. However, I wanted to highlight that persistent eye and vision problems may be encountered for a small number of users."

He went on: "These drugs, when used under the control of physicians and at the recommended doses, provide very important sexual and mental support, uncontrolled and inappropriate doses should not be used or repeated."

Pharmaceutical company Pfizer launched Viagra in 1998. Sildenafil is the generic version of the drug.

A spokesperson for Pfizer told Newsweek: "Pfizer is aware of reports incorrectly citing Viagra as the medicine linked to a retrospective case study published in the Frontiers of Neurology. The article refers to study subjects who had taken sildenafil 100mg without a prescription."

The spokesperson went on: "It is not stated in the case report where the medicine was acquired by the study subjects, therefore it cannot, and should not, be attributed to Viagra. The World Health Organization has estimated that patients who order medicines from "rogue" online pharmacies – those that conceal their true location and the source of their medicines – have a 50% chance of receiving a counterfeit medicine.

"Patient safety and the appropriate use of our medicines is of the utmost importance to Pfizer. Since its approval in 1998 as a treatment for erectile dysfunction, more than 67 million men around the world have been treated with Viagra. The safety profile of Viagra is supported by more than 74 double blind placebo-controlled clinical studies involving 9,570 patients. Regulatory product information is available here."

Correction 2/7/20, [05:10 a.m. ET]: This article was updated to clarify the core ingredient of Viagra was responsible but not necessarily the product marketed as Viagra itself. This article was updated with comment from Pfizer.