Bad breath can be cured. There multiple reasons to it and all of them can be treated successfully.

Let's list the most common reasons and their treatments below:

  1. Plaque & calculus  -  Treatment is scaling or cleaning of teeth and gums
  2. Cavity in the tooth - Filling or RCT of the tooth
  3. Coated tongue - Cleaning the tongue using a tongue scrapper or brush
  4. Smoking and Alcohol - Stopping the habit :-)
  5. Dry mouth - Sip water regularly, chew sugar-free gums

Other than this there can be problems with Sinus, tonsillitis or other problems with stomach and intestines. For that you will have to consult an ENT specialist or a gastro-enterologist. 

Can you try something before you visit your dentist/ doctor?

Definitely. Use a non-alcohol based chlorhexidine mouth-rinse for a week. Follow the instructions given on the bottle. If the problem persists or becomes worse, time to fix an appointment with your dentist.