If you haven't hit your medical deductible already, you certainly don't want to make any unnecessary trips to the doctor's office. But it is cold and flu season and they're both going around. If you're feeling sick you're probably trying to decide whether you need a doctor's appointment.

There are many medical apps in the app stores that help answer that question. Ada is my favorite because it's free and does a very good job of asking the right questions to give a good answer.

Ada was developed by a team of doctors and currently has over 5-million users. Here's how it works:

Ada gets to know you by answering some basic questions about your health and the health of your family. Once those questions have been answered, it asks about your current symptoms. If you answer that you have a headache, Ada makes a note then asks about other symptoms. Once it has the answers it needs, Ada uses artificial intelligence to come up with an answer using medical data from around the world.

Stuffy nose, headache, sneezing and coughing could be the early stages of the flu or just the common cold. You figured that before downloading the app. Ada has much more information and will show the ailments of other patients with the same symptoms. Four in 10 patients with the same symptoms were diagnosed with the flu while five in 10 just had a cold.

Ada is a free app for both iPhones and Android devices. It is by no means a replacement for a doctor but it may help you decide whether you need to make an appointment or just take two aspirin and go to bed.