However, it can also be caused by an underlying medical condition.
One of these conditions is sinus related problems.
If you think sinusitis is the cause of your breath odor problem you need to understand the link between the condition and halitosis in order to help you eradicate your bad breath.
One of the main reasons for people with sinus problems developing halitosis is that the mucus produced acts as a breeding ground for bacteria.
This is particularly true if you have developed a post nasal drip.
The only way to completely cure the sinus related bad breath is to treat your sinusitis, which will necessitate a trip to your doctor.
Once your doctor has helped cure the sinus problem, or at least reduced the frequency and intensity of the symptoms, your breath odor problem should start to reduce.
It will take several weeks to go completely, and it is especially important to maintain high standards of oral hygiene during this time.
It is not just an excess of phlegm feeding bacteria which can lead sinusitus sufferers to develop bad breath.
Another leading cause of unpleasant breath is a dry mouth, as with an absence of the neutralising saliva comes an increased ability for bacteria to spread.
Sinusitus is often treated with antihistamines, a common side effect of which is a dry mouth.
You can counteract the effect of the dry mouth by staying well hydrated.
This will need to be water as caffeine and alcohol worsen breath odor, and sugary drinks, including fruit juices, are a big factor in gum disease and other dental problems which are a big contributing factor to halitosis.
If you want to avoid the side effects of taking medication for sinus problems, there are natural ways of treating your condition.
There are tablets and sprays available which will not cure your sinus problems completely, but will relieve the symptoms greatly.
Nasal irrigation is becoming increasingly popular as it is effective for most people.
Devices suitable for this can be readily bought from a chemist or internet supplier.
Regular use of nasal irrigation not only reduces the likelihood of suffering an attack of sinusitis, but also relieves post nasal drips.
If you are still suffering from bad breath several weeks after treating your sinusitis, take a trip to your dental hygienist.
Even minor oral problems, such as a little plaque build up or small periodontal pockets, can help sustain a halitosis problem.