Various kinds of infections can contribute to a constant sweet taste in the mouth. Scientists said that virus and bacteria could have the bad impact on the nerves which results in some changes in tastes. For example, a bacterium called Pseudomonas causes Pseudomonas infection which can cause sinusitis together with changes in taste including a sweet taste in the mouth.

According to a study by the National Institutes of Health published on its website, people suffering from blocked sinuses caused by inflammation have changes in taste including a sweet taste in the mouth.

Nutritionists confirmed that inappropriate diets with dietary deficiency could lead to an uncommonly unpleasant sweet taste. They researched a group of men who were served with improper diets for 60 days.

The results of the research showed that there was 80% of participants in this study had a sweet taste in mouth while the rest had experienced changes in taste including a sour taste, salty taste, and fatty taste.

Another recent study also found that zinc, folic acid, and vitamin B deficiency caused strange changes in taste.