My doctor prescribes azithromycin 500mg /day for 7 days for my genital infection. is it safe to take such high dosage? i have checked the drug information on the internet that 500mg to be taken on day 1 and then 250mg for 2 to 5th day?

This actually isn't such a high dose of azithromycin and won't cause any harm. That said, it's more than usually needed, although it depends on exactly what kind of "genital infection" is being treated. (The most common genital infection treated with azithromycin is chlamydia, which only requires a single 1 g dose. OTOH, chlamydia is uncommon at your age, so probably it's something else.)