Bad breath (halitosis)
Simple rinses and home remedies
While dogs usually don't consider halitosis a reason to be any less close up and personal with those they love, humans in general do.
On causes of bad breath
Generally speaking, bad breath (fetor ex ore) is a sign of lack of oral cleanliness and/or bacterial infection such as in tooth decay or periodontal disease1, and if the latter, is best taken seriously since it reveals the presence of a large bacterial load ("morning breath") incl. plenty of "caries bacteria" such as streptococcus mutans.
Obviously, bad breath also may be caused by alcohol consumption, tobacco, diet (garlic, onions, sharp spices, sugar and starches feeding acid-producing bacteria), fasting (where the body's efforts at cleansing itself seem to typically include a thickly coated tongue) and even lack of saliva flow or dry mouth. Saliva in addition to being a vital link in dental health maintenance and restoration (see Demineralisation/Remineralisation) is also nature's inbuilt mouth rinse that automatically washes odor-causing bacteria from your mouth.
In rarer cases, bad breath could be a sign of certain medical conditions (postnasal drip, tonsillitis, lung infections, sinusitis, mouth ulcers, digestive disturbances incl. insufficient stomach acid and constipation, and others (I've even seen liver and kidney ailments as well as diabetes mentioned). Naturally, in all such instances, the topical and local remedies listed in the following will only work temporarily and the root cause needs to be addressed.
Other halitosis causes I have seen suggested include damage to the normal non-pathogenic) microorganisms of the oral cavity from drinking chlorinated tap water and/or undergoing antibiotic (Tetracycline) treatment. Another theory posits that bad breath is due to anaerobic sulfur-producing bacteria breeding within the tongue and throat and giving off malodorous volatile sulfur compounds.
Ironically even alcohol-based mouthwashes used to "freshen one's breath" can be a cause of bad breath, since the alcohol can dry your mouth out. Without proper salivary flow providing a self-cleansing action, bacteria as mentioned aren't washed away.3
Bad breath natural remedies
Specifically and since this site is about promoting simple, inexpensive DIY solutions to common problems (here: bad breath), for starters I will again come back to my favourite toothache remedy ...
Salt water against bad breath
Gargling and thoroughly rinsing one's mouth with a strong salt solution can work wonders for bad breath symptoms (removing "rotting" leftover food particles and likely killing off odour-producing bacteria which lie at the root of the unpleasant smell). Probably due to the same bactericidal mechanism of action, I have seen salt water equally recommended for relieving a sore throat.
Variations of the salt water rinse can be made in any number of ways, for instance by adding lemon or using oil (for instance mustard oil) as the basis instead of water (also see Oil pulling).
Baking soda (sodium bicarbonate) against halitosis
Considering that it is a famous "mopper-upper" of bad or persistent odours, baking soda rinses (while less inexpensive than salt) should have a similarly or even stronger positive effect. Baking soda, in addition to its many time-honoured applications, has indeed been used and recommended both for brushing teeth and in baths and rinses, see More about baking soda.
Drinking water & hydrating your mouth
Since as mentioned above, bad breath can be caused by dry mouth (dry mouth allowing caries-promoting bacteria to flourish3) simple water drinking can erase any traces of bad odour (and after rinsing seems like the obvious first-aid measure to take). You can help to make sure that your mouth stays hydrated by chewing sugar-free xylitol gum or regularly "rinsing" with xylitol. Note: certain medications can cause dry mouth.4
Hydrogen peroxide
is another of the trusty standbys for a number of DIY health applications and works by eliminating bacteria.2 Only use 3% (or even lower) food grade hydrogen peroxide for gargling (or make sure to properly dilute a more concentrated hydrogen peroxide or you might seriously hurt/damage your mouth, undiluted hydrogen peroxide is highly aggressive and not to be trifled with!).
Clean your tongue
gently but thoroughly and regularly of any malodorous films and deposits which may have accumulated (for instance during sleep), using a toothbrush, spoon or special tongue scraper. Simultaneously, you will likely have removed large amounts of caries bacteria from your mouth (see Tongue Cleaning).
Clean between your teeth
Food rests trapped between your teeth not only are one of the main causes of tooth decay but can also cause oral malodour. More at Interstitial Cleaning (Flossing).
Oil pulling
This simple health practice has been credited with numerous cleaning and healing benefits, including cleaning up mouths who formerly suffered from "morning breath" etc. (to wit this testimonial: "My breath has become very pleasant in the morning. When I ran out of sesame oil and did not do my oil pulling, I did notice my breath becoming slightly smelly in the morning. This condition instantly reversed itself as soon as I started oil pulling in the morning again.") In fact, a scientific study titled "Effect of oil pulling on halitosis and microorganisms causing halitosis" arrived at the result that oil pulling was as effective as chlorhexidine for bad breath and the associated microorganisms - which in light of the strong antimicrobial power of chlorhexidine is very impressive indeed. Compare Oil Pulling.
Xylitol
The natural sugar replacement xylitol has permanently improved people's "morning breath" and cleared coated tongues by suppressing cariogenic streptococcus mutans bacteria. In addition to rather costly xylitol chewing gum and candy, the easiest and most economical way of benefitting from xylitol's caries-healing properties consists in "rinsing" with it several times a day (without flushing with water afterwards) and leaving it in your mouth overnight. Details about xylitol and Rinsing with xylitol.
Raw green foods, parsley, coriander leaves, sage leaves & chlorophyll
Particularly when much of the odour comes from the lungs (such as after ingestion of garlic), I've found eating raw green foods and chewing parsley (chlorophyll apparently works as a natural deodorant) to be very effective and helpful. A slightly more complicated recipe I saw suggested involved boiling parsley sprigs with ground cloves and using it as an effective remover of mouth odours.
If you grow your own wheatgrass or have it available in powder form (health food stores), you have another chlorophyll-rich food you can use against mouth odour. Spirulina, barley green etc. should work similarly. And indeed ...
Cayenne pepper for tooth brushing
Someone who used to suffer from inflamed and receding gums reported that after starting to brush her teeth with plain cayenne powder, all previous gum issues were resolved including "morning breath".
Chlorella
I have read several reports of bad breath disappearing after the person began to regularly consume chlorella. (Also compare Chlorella Growth Factor.) In addition to the general benefits of chlorella intake, its high chlorophyll content is likely to play a role here.
Milk & dairy - friend or foe
A friend has told me that drinking milk "mopped up" all garlic odour from her mouth. (Somewhat relatedly, I have seen a "household" tip for removing odours from cupboards consisting in placing a pot of boiling hot milk inside the cupboard, which will absorb the odour.)
On the other hand, there are reports from people that milk or cheese consumption has induced bad breath. The different reactions may be due to differing bacterial populations in people's mouths.
Activated charcoal
is a highly absorptive substance and "bound to bind" noxious malodorous substances in your mouth.
Cardamon, clove, fennel
Chewing cardamon, fennel or clove (the more the merrier) can suppress mouth odour (such as after meals). These seeds (or flower buds in the case of the cloves) are also easy to carry in case the need for a breath freshener arises while away from home.
Apple cider vinegar
In addition to its numerous reported panacea-like qualities, apple cider vinegar also doubles up as an efficient mouthwash. Suggestion: dilute a teaspoon of apple cider vinegar in a cup of water and gargle (but since it is not easy on tooth enamel, caution is advised - or try mixing it with baking soda before use to raise its pH to tooth-friendly levels, or rinse with baking soda afterwards).
Cinnamon and honey rinse
Mix one teaspoon of honey and cinnamon powder each in warm water and gargle with this mixture in the morning. "Breath stays fresh throughout the day."
Echinacea & goldenseal powder
If the bad smell comes from a putrefying tooth (decaying tissue), according to herbalist Dr. John Christopher the blood-purifying and anti-putrefactive herb echinacea will eliminate foul odors and fetid discharges and arrest pus formation. Suggestion: pack the tooth with herb powder, then seal with a cotton ball soaked in tea tree, mint or similar disinfecting oil.
Rosemary
(Rosmarinus officinalis, flowering tops or leaves)
Apparently rosemary can make an extremely effective mouthwash and may erase halitosis almost instantaneously. One suggested preparation of the herb would be to heat 1 pint of water, after removing from fire add 3 tsp of dried rosemary, cover and steep for half an hour. Strain and keep refrigerated. Gargle and rinse with this decoction your mouth as needed. A simpler way (if available) is using rosemary essential oil.
Disinfectant essential oils
These can be very pleasant and help combat odour-causing bacteria. More
Various anti-bad-breath suggestions
Grapefruit seed extract (added to toothpaste), pranayama done in the morning, cream of tartar (Potassium bitartrate) (these as well as some of the above suggestions gleaned from earthclinic.com). Also see Herbal and plant-based toothache remedies for germ-killing herbal preparations such as tea tree oil which will also fight bacteria causing bad breath, and make you even more lovable. :-)
Sinus conditions
leading to thick mucus/phlegm discharge and bad breath may yield to herbal approaches, magnesium supplementation, hydrogen peroxide, removing dairy and other mucus-producing food, using a neti pot to clean the nasal passages (incl. with salt water), etc.
Acidophilus, intestinal cleansing
If the odour arises from the lower digestive system, taking a probiotic supplement such as acidophilus may be very helpful as well as certain herbs (such as Goldenseal) and of course intestinal cleansing, increased water consumption etc.
E-book on healing bad breath, gums and teeth naturally
This ebook is endorsed by eminent dental health researcher Dr. Paul Keyes, DDS, MS, (a rare honour I would think). Dr. Keyes is a heavy proponent of "non-surgical solutions to dental health" (and among other things adjunct clinical professor of periodontology at the Temple University School of Dentistry, co-founder of the International Dental Health Association and former Dental Director at the National Institutes of Health [NIH]).
While the ebook is called The Bad Breath Report, this is actually an understatement or misnomer since it is about much more
than "just" how to naturally have fresh rather than bad breath, it is also about healing gums and teeth by addressing root causes, naturally whitening your teeth etc. Promotional offer US$ 19.95
Footnotes
1 Periodontal disease: a gum infection which can be caused among other things by the accumulation of plaque (refer to Dental Care & Oral Hygiene for many cleaning suggestions, natural home-made mouthwashs, flossing etc.).
2 See for instance Hydrogen Peroxide (H2O2) and baking soda permanently heal periodontitis after surgery fails.
3 Compare Dental health prerequisite number 4: proper salivary flow.
4 More at Dry mouth (xerostomia): On causes, remedies & treatments of inadequate natural production of saliva.