Bad breath because of tonsils is a different condition from bad breath caused by bacteria living on the tongue and breaking down cells and proteins naturally present in the mouth. When bacteria colonize and infect the tonsils, the condition is tonsillitis, and it is an infection that requires medical attention.
The bacteria that cause tonsillitis are almost always Streptococcus pyogenes bacteria – most people know the condition as strept throat. The infected tonsils become extremely inflamed, developing pockets of pus in the tonsillar crypts and causing an extremely sore throat, often accompanied by fever and vomiting. When the tonsil produces pus bad breath results. Bad breath because of tonsils has a rotten meat odor that is subtly different from the rotten egg sulfur smell produced in ordinary bad breath. In addition, the unfortunate person with tonsillitis generally feels extremely unwell and there is no doubt that something serious is going on.
Bad breath because of tonsils is not the worst consequence of strept throat. A greater danger is the risk of the infection being followed by scarlet fever, or rheumatic fever, which can damage the heart. Most cases of strept throat will get better on their own, but treatment with antibiotics risks the other diseases from developing later. When a tonsil produces pus bad breath and fever, see your doctor and get a diagnosis. If you have strept throat, you will need an antibiotic.
Not all sore throats are caused by Streptococcus pyogenes, however – many sore throats are caused by viruses, or by bacteria that have no serious consequences. They simply cause misery for a few days, then they're gone. Your body's immune system should be able to take care of these transient infections and no antibiotic treatment is required. An infected tonsil produces pus bad breath generally only in strept throat; however, if you do get bad breath because of tonsils with a sore throat that is not caused by Streptococcus pyogenes, the problem should resolve when the sore throat does.
If you think you have bad breath because of tonsils, but you do not have a very sore throat, the chances are that the problem is not located on the tonsils, but on the tongue or in other areas of the mouth where sulfur compound- producing bacteria thrive. This is a different story altogether. If the problem is ongoing, see your dentist or doctor for a professional opinion, then tackle it with one of the many available remedies.