Eating sugary or sweet foods can cause a temporary sweet aftertaste in the mouth. However, a persistent sweet taste in the mouth can be a sign of a more serious condition.
A sweet taste in the mouth can be a signal of the body having trouble regulating blood sugar, which may be due to diabetes. There is also a range of other possible causes, each requiring specific care.
Unlike an aftertaste caused by eating foods containing sugar or artificial sweeteners, a persistent sweet taste in the mouth is typically caused by an underlying medical condition.
These conditions can be serious and will often require medical attention, so it is vital to receive a proper diagnosis.
Diabetes is a common cause of a sweet taste in the mouth. Diabetes affects how well the body can use insulin, which has a direct effect on the body's ability to control blood sugar.
Uncontrolled diabetes can result in high levels of sugar in the blood. Diabetes can sometimes cause a sweet taste in the mouth and is often accompanied by other symptoms.
Additional symptoms include:
- reduced ability to taste the sweetness in foods
- blurred vision
- excessive thirst
- excessive urination
- extreme fatigue
Diabetes may also cause a serious complication called diabetic ketoacidosis. This happens when the body cannot use sugar for fuel and begins using fat instead. This causes an acid called ketones to build up in the body.
Excess ketones in the body can cause a sweet, fruity smell and taste in the mouth. Diabetic ketoacidosis may cause other symptoms, including:
- extreme thirst
- nausea and vomiting
- abdominal cramping
Low carb dieting
People who are on low carbohydrate diets may find that they develop a similar fruity, sweet taste in the mouth. Carbohydrates are a common source of fuel in the body and going without them makes the body burn fat instead.
This process is called ketosis and causes ketones to build up in the bloodstream, producing a sweet taste in the mouth.
Anyone embarking on a low-carb or ketogenic diet should get guidance from a nutritionist or healthcare professional. Getting advice might help prevent harmful levels of ketones building up in a person's body.
Certain bacterial infections can trigger a sweet taste in the mouth. Infections that affect the airways can interfere with how the brain responds to the taste senses.
Even simple infections, such as a cold, flu, or sinus infection, may cause the saliva to have more glucose in it. Glucose is a type of sugar, so may cause a sweet taste in the mouth.
If this is the case, the sweet taste will usually clear up when the infection is treated.
Nerve damage can also cause a persistent sweet taste in the mouth. People who experience seizures or who have had a stroke may experience sensory dysfunction. This can affect their senses, including taste and smell.
The outcome of this damage is complex and may be different in each case. In some cases, people may experience a sweet taste in their mouth that does not go away or that comes and goes.
Gastroesophageal reflux disease
Some people with gastroesophageal reflux disease (GERD) also complain of having a sweet or metallic taste in their mouth.
This is due to digestive acids that back up into the food pipe (esophagus) and eventually the mouth. This taste may seem to originate at the back of the mouth. Managing GERD with dietary and lifestyle changes will reduce symptoms.
Pregnancy is another possible cause of a sweet taste in the mouth. Pregnancy causes changes in a woman's hormones levels and digestive system, both of which can affect taste and smell.
Pregnant women may experience unexplainable sweet or metallic tastes in the mouth. The underlying cause could still be another condition, such as GERD or gestational diabetes, so any woman experiencing persistent changes in taste should talk with a doctor.
Some medications may also be to blame for a sweet taste in the mouth. Chemotherapy drugs often alter a person's sense of taste.
This is a minor side effect of drugs that are used for serious illnesses, but doctors will still want to check and be sure that it is the medications causing the symptom.
If the sweet taste is affecting a person's diet or quality of life, doctors may be able to prescribe an alternative.
Lung cancer is an uncommon cause of a sweet taste in the mouth, but it should not be overlooked. Rarely, tumors in the lung or respiratory tract can raise a person's hormones levels and affect their sense of taste.
Some causes of a sweet taste affect the respiratory and olfactory systems directly, while others affect the hormones or neurological system.
A doctor will usually perform a physical exam in addition to diagnostic tests. They will also ask a person about their medical history or any medications they are taking.
Possible tests include:
- blood tests to check for bacterial or viral infections, hormone levels, and blood sugar levels
- CT scans or MRIs to check for signs of growths and cancers
- brain scans to check for nerve damage and to test neurological response
- an endoscopy to check for signs of digestive disorders
Once the cause of the unusual taste is determined, doctors will help the person find a working treatment plan to keep their symptoms in check.
Treatment will vary greatly depending on the cause. For instance, someone with diabetes may find relief with insulin therapy, exercise, and a healthful diet, but someone with a respiratory infection may require antibiotics. It is best to discuss the individual case with a doctor.
Experiencing an unexplained sweet taste in the mouth just once is not usually cause for concern. However, if the sweet taste happens frequently or for long periods of time, it is a good idea to see a doctor.
A proper diagnosis is the best way to treat an underlying condition early and avoid serious complications.