The press was buzzing over a new research study which showed that Viagra doesn't appear to negatively affect vision. We've read through the research, so you don't have to. Here's the title:
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Arch Ophthalmol. 2009;127(4):367-373.
"Tadalafil" is the generic name of Cialis; "Sildenafil" is the generic name of Viagra.
What they did:
Took generally healthy men with mild erectile dysfunction. Gave some Viagra (50 mg), some Cialis (5 mg), and some a placebo every day for 6 months. Checked their retinas; everything seemed fine.
Who paid for the study:
Eli Lilly, the makers of Cialis, paid for the study. They wanted to show that Cialis is safe for everyday use. Viagra was included in the study for comparison. Levitra wasn't tested.
What it tells us:
It's pretty safe to take Viagra or Cialis every day, and it doesn't cause any medium-term eye problems. The vast majority of patients were able to tolerate the drugs without any serious problems.
What it doesn't tell us:
The test only went on for 6 months, so it doesn't provide information on long-term effects.
Cool things we found out:
Cialis reaches peak plasma concentrations 2 hours after a single dose
Viagra reaches peak plasma concentrations 30 minutes to two and a half hours (mean 88 minutes; median 60 minutes)
So it seems like Viagra takes full effect very differently for different people, even on an empty stomach. For some people it takes only 30 minutes, others over two hours. Cialis seems to take two hours to take full effect.
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