yes US $ are accepted but you will loose in change. You better change your US $ at a change office in the airport or for a better change rate in the city, where you can find plenty of change offices.
If you need any more information about Istanbul, do not hesitate to ask. email@example.com about 5 years ago
Firstly, for your upcoming arrival hoşgeldin (welcome). Lira is the local currency - I would convert to that. Some tour companies and hotels advertise in Euro and do accept Euro, but US dollars are rarely accepted (although money is money in some eyes!) Taxis, shops outside Sultanahmet and majority of restaurants and attractions are Lira only. Menu prices are in Lira - if you want to avoid confusion when paying for meals have lira. Carpet shops might accept US dollars - just depends who you deal with. Also bare in mind, I believe offering Lira will give you a better deal at places like the grand bazaar. There are currency exchange places around Istanbul where you can convert your US to Lira. about 5 years ago
I would recommend you to find an exchange office (plenty of them everywhere) and do some exchange.
Or instead you can enter any bank office and you can convert your money without loss.
You can see all exchange rates on the exchange offices boards; and ask the bank staff about the exchange rates.
And definitely I would not recommend to offer paying in US dollars or Euros.
Have a nice trip, about 5 years ago