Bad breath - halitosis, if we're being technical - is one of the most common oral health concerns, and one of the least well understood.
The instinct is to treat it as a hygiene problem: brush more, use a strong mouthwash, chew a mint. For most people with persistent bad breath, that instinct is only partially right. The underlying cause is almost always microbial, not mechanical - and understanding the difference matters.
Where the smell actually comes from
The odour associated with bad breath is almost entirely produced by bacteria - specifically, anaerobic bacteria that thrive in low-oxygen environments: in the pockets between teeth and gums, on the dorsal surface of the tongue, and in areas where saliva doesn't reach easily.
These bacteria metabolise proteins and produce volatile sulphur compounds (VSCs): hydrogen sulphide, methyl mercaptan, and dimethyl sulphide. These are the compounds responsible for the characteristic odour. Everyone has these bacteria; the question is whether they're in balance with the rest of the oral microbiome, and whether conditions in your mouth are allowing them to proliferate.
Why strong mouthwash can make things worse
Alcohol-based mouthwashes are effective at killing bacteria immediately after use. That's also their limitation.
Alcohol is non-selective - it kills pathogenic and beneficial bacteria indiscriminately, and it dries out the oral mucosa. A dry mouth is a less hospitable environment for aerobic bacteria (which keep anaerobic species in check) and a more hospitable one for the anaerobes that produce VSCs. The result - experienced by many regular users of alcohol-based rinses - is a brief improvement followed by breath that returns worse than before.
This isn't an argument against mouthwash. It's an argument for choosing one that works with your microbiome rather than against it.
What actually helps
Addressing persistent bad breath means addressing the conditions that allow anaerobic bacteria to proliferate, rather than simply trying to eliminate them on contact.
Hydration is consistently underappreciated. Saliva is the mouth's primary defence against bacterial overgrowth - it's antimicrobial, it buffers acid, and it physically washes the oral surface. Chronic mild dehydration is one of the most common contributors to persistent bad breath and one of the simplest to address.
Tongue cleaning has more impact than most people realise. A significant proportion of VSC-producing bacteria live on the dorsal surface of the tongue, where toothbrushing doesn't reach effectively. A tongue scraper used once daily removes a large part of the protein substrate these bacteria feed on.
When it comes to mouthwash, cetylpyridinium chloride (CPC) is an active ingredient with good published evidence for targeted antimicrobial action - effective against VSC-producing species without the broad disruption associated with alcohol. It's found in some alcohol-free mouthwashes and is worth looking for on an ingredient label.
And if you've addressed lifestyle factors and the issue persists: see your dentist. Persistent bad breath can be associated with untreated cavities, gum disease, or other conditions that a mouthwash will not resolve.
→ Laro's Active Mouth Rinse is alcohol-free and contains CPC - formulated to work with your oral microbiome, not against it. Explore the range.