BY NOW, readers of this column should be very aware that both prescription and over-the-counter drugs can cause many side effects. Some of these problems, though very serious, go unnoticed for a long time and are recognised only when major damage has occurred.

Many drugs affect the mouth in various ways. These are usually very obvious, and if we look out for them, they can provide early warning of trouble. Here are some common ways in which medicines can affect your mouth.

DRY MOUTH

Hundreds of medicines can prevent the salivary glands from manufacturing enough saliva to keep the mouth moist, resulting in an uncomfortably dry mouth. Saliva has many important functions, and the consequences of a dry mouth range from simple discomfort, to abnormal taste, an inability to soften and chew food, indigestion, bad breath, inflammation of the mouth and even tooth decay.

The most common medications that cause dry mouth include blood-pressure medicines, anti-depressants, anti-diarrhoeals, anti-histamines, anti-psychotic drugs, decongestants, diuretics, muscle relaxants, oral inhalants for asthma and tranquillisers.

ALTERED TASTE

This is another common complaint that may be brought on by many medicines prescribed for conditions like heart disease, circulation problems, and nervous-system disorders. The popular arthritis medications - NSAIDs (non-steroidal anti-inflammatory drugs), respiratory inhalants for asthma and bronchitis or nicotine patches used to help people stop smoking often affect your taste too.

Advancing age may also play a role in taste impairment and medication often worsens this. The loss of appetite so common among the elderly may be related to drug use. This disturbance may be described as a 'bad' or 'metallic' taste, while others may complain that everything tastes like sawdust. Impaired taste can also be a sign of a vitamin B12 deficiency, so ask your physician about a B12 blood test.

BLEEDING IN MOUTH

Some medications such as heparin, warfarin and even aspirin are anticoagulants used to reduce blood clotting. Bleeding from the mouth is a well-known and important side effect to be aware of. Certain dietary supplements, notably vitamin E, fish oil and garlic, improve blood flow and have anti-coagulant properties. In my experience, with doctor and patient working together, the use of these supplements can reduce the need for anticoagulant medicines.

GUM, TISSUE REACTIONS

Other oral disturbances - inflammation, sores and tissue discolouration - may be related to blood-pressure medications, immunosuppressive drugs, oral contraceptives or chemotherapy. Swelling or overgrowth of gum tissue may be caused by anti-epileptic medications or the immunosuppressants.

This is probably one of the more serious side effects since tissue overgrowth in the mouth could also signal negative effects in other areas of the body. This swelling involves the connective tissues and may indicate more serious underlying problems.

TOOTH DECAY

Although this is beginning to change, not long ago, nearly every children's cough and cold medication came as a sugary red, green or orange syrup. Obviously, the more sugar, the more tooth decay. Other potentially sugary meds or supplements include liquid medications in general, cough drops, vitamins, antacids and antifungal agents.

TALK TO YOUR DOC

If you experience uncomfortable side effects in your mouth and suspect they're due to medications, do not simply stop taking your medicine. Instead, consult your physician and ask about changing to a different medication, or decreasing or eliminating the drug.

Very often, your doctor can prescribe other treatment options that do not have the same side effects. Perhaps a natural treatment with fewer side effects is an option as well.

TIPS ON PREVENTION

Read medication warning labels carefully for potential side effects, and be alert to changes in your oral health after you start taking the medication. Not all drugs in all categories listed above will result in the specific side effect described.

Make it a habit to frequently sip water and avoid sugar, even in medicines. When sugarless medication is not available, rinse your mouth (or your child's mouth) after taking the medicine. This will get rid of most of the sugary, syrupy residue. This is especially important for medications taken prior to bed.

Steer clear of coffee, alcohol and tobacco as these can dry out the mouth. A dry mouth makes you more prone to tooth decay. Suck on sugarless hard candy or chew sugarless gum to stimulate saliva flow.