Gum disease is rarely the cause of bad breath. It’s more likely that your sinus problem holds the key to your halitosis. Mouth bacteria are anaerobic meaning they thrive in airless conditions. When your mouth is closed, oxygen rich saliva helps to keep bacteria at bay. But because of your sinus condition, you are probably breathing through your mouth, providing bacteria with ideal conditions in which to thrive.

Almost anything that dries the mouth can produce bad breath. Some medications, such as the antihistamines and decongestants which sinusitis sufferers often use, can make the problem worse since they dry the mouth further. You can help keep your mouth moist by chewing gum or always keeping a bottle of water handy (preferably with a squeeze of lemon juice in it).

Mouthwashes don’t provide long term relief from halitosis since they cannot kill the bacteria which usually reside under layers of plaque and mucous. Instead, they simply provide a short term mask for the odour. What’s more, the alcohol contained in many mouthwashes will dry the mouth out, further exacerbating the problem.

Do what you can to clear up your sinus infection since some are caused by bacteria which produce their own foul smelling sulphur gases. Avoid antibiotics if you can. Instead, boost your intake of natural bactericides, such as garlic and onions (yes, even for bad breath!), cayenne, golden seal and echinacea. Bioflavonoids (like quercetin), essential fatty acids and carotenoids block the enzymes involved in mucous production and inflammation.

These should all be made a part of your diet either through supplements or by increasing your intake of fresh raw vegetables, seeds and oily fish. Sinusitis can also be caused by food intolerance and allergy, so you might consider trying an exclusion diet for a while and monitoring how your sinuses respond. Dairy products are the most likely culprits.

My husband has a persistent white coating on his tongue. He was taking doxycycline for acne, but now uses benzoyl peroxide gel topically. The coating disappears when he stops using the gel.

My naturopath believes it is a food allergy, but hasn’t really been able to help. Can you? – BG, Stockport

A Homoeopaths, and practitioners of Ayurvedic and traditional Chinese medicine all place great importance on the state of the tongue for their diagnoses. You might consider a trip to one of these practitioners for your daughter’s and husband’s health problems.

In Chinese medicine, such discoloration could point to stomach or gut problems but, without an examination, it is impossible to say for sure. Our own Harald Gaier suspects a condition called hypochlorhydria – low stomach acid. Your daughter is too young to test for this condition (which requires swallowing a large capsule), but you might send your husband for tests (Biolab, in London, will do them; tel: 020 7636 5959).

The Hib jab may have presented a major challenge to your child’s immature immune system, from which she has simply not been able to recover. You may wish to take your daughter to a reputable homoeopath for a course of treatment to deal with the after-effects of the vaccine. Homoeopathic remedies such as Nat Sulph, Mercurius and Chelidonium are indicated for tongue discoloration.

It’s also possible that the jab (or the doxycycline; see previous letter) triggered a Candida albicans overgrowth. When this happens, Candida becomes invasive, enters the bloodstream and causes problems in organs such as the liver, kidneys, heart, spleen, lungs and brain, as well as ‘leaky-gut’ syndrome, allergies, urinary tract and skin infections, hormonal imbalances and musculoskeletal pain.

Treating fungal infections is less straightforward than treating bacterial infections because fungi are rather more complex than bacteria. However, with the help of a good practitioner, there are several ways to proceed. Dealing with Candida requires what is known as the 4R method of treatment: 1) Remove the fungi – sometimes with antibiotics, but also with herbs; 2) Replace digestive secretions if necessary (hydrochloric acid, pancreatic enzymes); 3) Reinoculate the body with good nutrition and probiotics that support immune function; 4) Repair the intestinal wall and heal the leaky gut with nutrients such as zinc, antioxidants and L-glutamine. Each of these steps, however, will need to be modified to take your daughter’s young age into account.

Even if your child is following a good diet, if she has Candida, you will have to be scrupulous about certain foods. Yeasted foods (such as breads, muffins and biscuits) need to be strictly avoided in the early weeks of treatment and sometimes for longer.

Sugar-containing foods, including high-carbohydrate vegetables, fruits and fruit juices, are also out. Replace these with low-carbohydrate vegetables to provide fibre, fish, meat, poultry and eggs, and unprocessed nuts, seeds and oils.

Several herbs are useful both internally and topically for Candida but, again, some of these, like barberry (Berberis) tincture and tea-tree mouth rinse, may not be suitable for young children. You should always consult a qualified herbalist before giving any of these to your child.