While struggling with depression, Mugisha, a Kigali resident, sought medical help and the doctor prescribed a dose of antidepressants. After some time, he noticed that his lips were excessively dry.

On consulting the doctor who prescribed the medication, he was told that the dryness in his mouth was an effect of the antidepressants, and he was advised to drink water regularly, and avoid alcohol and caffeinated beverages as they could worsen the condition.

Dry mouth, also known as xerostomia, is an uncomfortable condition, and although experts say that dehydration is one of its causes, there is more to it. It is a condition in which the salivary glands in the mouth don’t make enough saliva to keep the mouth wet.

According to Dr Gilbert Nuwagaba, an adult and paediatric dentistry specialist, saliva is necessary as it moistens and cleanses the mouths and helps in digesting food, additionally, it prevents infection by controlling bacteria and fungi in the mouth. Therefore, without saliva, the mouth becomes dry, thus risking increased plaque, tooth decay and gum disease.

He says that dry mouth isn’t just about thirst, but can also cause difficulty eating, speaking, swallowing and bad breath.

Dr Nuwagaba says that apart from dehydration, some medications provoke xerostomia, which is why it is necessary to check for the side effects of the medication before taking it.

Studies suggest that medications used to treat hypertension like alpha blockers and beta blockers, have side effects, including dry mouth. Researchers also found calcium channel blockers can inhibit saliva secretion. Experts say that angiotensin-converting enzyme-ACE inhibitors used for treating high blood pressure, diabetes and kidney problems can also lead to oral dryness.

Other studies suggest the tricyclic antidepressants (TCAs) and monoamine oxidase inhibitors (MOAIs), which are sometimes used in treating Parkinson’s disease, and others, reportedly cause dry mouth.

Dr Nuwagaba notes that breathing through the mouth at night can also trigger dry mouth, this usually happens if one has a blocked nose or sleeps with the mouth open.

Other causes, he says, include cancer treatment such as radiotherapy or chemotherapy, and anxiety.

He also says that smoking or chewing tobacco affects how much saliva you make and instigates dry mouth.

"Dry mouth can be a side effect of medical conditions, such as HIV/AIDS, Alzheimer’s disease, diabetes, anaemia, cystic fibrosis, rheumatoid arthritis, Parkinson’s disease, hypertension, stroke, and mumps, and others,” Dr Nuwagaba says.

WebMD describes signs of dry mouth such as, sticky, dry feeling in the mouth, frequent thirst, sores in the mouth, sores or split skin at the corners of the mouth, cracked lips, a dry feeling in the throat, a burning or tingling sensation in the mouth and especially on the tongue, a dry, red, raw tongue, problems speaking or trouble tasting, chewing, and swallowing, hoarseness, dry nasal passages, and sore throat.

Dr Nuwagaba recommends some remedies to prevent oral dryness, for example, drinking enough water every day, sucking on ice cubes, averting the use of tobacco or recreational drugs, chewing sugarless gum, limiting alcohol, caffeine, salt and sugar intake, and breathing through the nose, not the mouth.

"If you do the above but the condition persists, inform your doctor to check for any underlying conditions or change any medications that might be causing your symptoms,” he says.

Dr Nuwagaba advises to take proper oral care such as brushing, flossing, and getting regular dental checkups so as to prevent tooth decay and gum disease caused by dry mouth.

Healthline encourages the use of alcohol-free mouthwash since it is effective in improving overall oral hygiene. More specifically, mouthwashes containing xylitol help promote saliva production. This may provide short-term relief.

Dr Nuwagaba adds that if dry mouth isn’t managed, it can result in complications such as persistent bad breath even after brushing, periodontitis, or inflammation around the tissue that surrounds the teeth, irritated gums due to bacteria, and candidiasis (the growth of excess fungus in the mouth.)