What is a mouthwash?
A mouthwash is a solution used to rinse the oral cavity. This may be to maintain oral hygiene, to prevent dental plaque, or for symptomatic relief.
A mouthwash is sometimes called a mouth rinse.
Who needs a mouthwash?
A mouthwash may be used short-term for a variety of conditions. Some examples follow.
- Halitosis (bad breath)
- Radiotherapy-induced mucositis
- Recurrent aphthous ulcers
- Oral lichen planus
- Acute mucositis associated with Stevens-Johnson syndrome / toxic epidermal necrolysis, or with erythema multiforme major
- After oral surgery
- As an adjuvant to toothbrushing to control bacterial plaque
- Adjuvant therapy for acute gingivitis and necrotising periodontitis.
A fluoride-containing mouthwash may be used to reduce the risk of cavities / dental caries.
What do mouthwashes contain?
Mouthwashes contain a variety of ingredients. The active ingredients include:
- Chlorhexidine gluconate – antimicrobial
- Povidone-iodine – antimicrobial
- Benzydamine hydrochloride – anti-inflammatory, analgesic, antimicrobial
- Essential oils, such as eucalyptol, menthol, methyl salicylate and thymol. These are often formulated in an alcohol-based solution – antimicrobial
- Cetylpyridinium chloride – antimicrobial
- Triclosan – anti-inflammatory, antimicrobial
- Sodium hypochlorite (dilute chlorine bleach) – antimicrobial
- Hydrogen peroxide – antimicrobial, bleach
- Anti-bacterial peroxidase enzymes, such as lysozyme, lactoferrin, glucose oxidase, lactoperoxidase – antimicrobial
- Fluoride – remineraliser, antimicrobial
- Sodium bicarbonate – alkaliniser
How do mouthwashes work?
The active ingredients in mouthwashes act in several ways.
- Antimicrobials kill bacteria, reducing plaque and halitosis.
- Anti-inflammatories decrease pro-inflammatory cytokines, reducing pain.
- Fluoride (fluorapatite, fluoro-hydroxyapatite) re-mineralises tooth enamel, enhancing resistance to acid and preventing cavity/caries formation.
- Bicarbonate alkalinises salivary pH. It reduces the erosive effect of acid produced by oral bacteria, and promotes enamel mineralisation, especially in people with dental caries.
How to use a mouthwash
Mouthwash is typically used twice-daily, as a short-term adjuvant to toothbrushing.
- Depending on the type and concentration, mouthwash may require dilution prior to use.
- Typically, 15–20 mL of solution is used.
- Empty the mouthwash into the mouth, swill it around vigorously, and gargle for at least 30 seconds.
- Spit out the mouthwash completely; do not swallow it.
What are the adverse effects of mouthwash?
The adverse effects of mouthwash depend on its ingredients, and include:
- Local irritation
- Allergic or hypersensitivity reactions, including contact stomatitis, urticaria and (rarely) anaphylaxis.
Adverse effects of chlorhexidine make it unsuitable for long-term use:
- Unpleasant or altered taste
- Burning sensation
- Desquamation and irritation of the oral mucosa
- Discolouration of soft tissues, teeth and restorations
- Supragingival calculus deposition
- Parotid swelling
Benzydamine has local anaesthetic and analgesic properties. It can cause:
- Numbness or tingling in the oral cavity
- Dry mouth
Ethanol associated side-effects may occur with mouthwashes containing essential oils.
- Mucosal irritation and dryness
- Oral pain, with intensity proportional to the concentration of ethanol
- Mouthwashes with > 20% ethanol risk keratosis, epithelial detachment, mucosal ulceration, gingivitis and petechiae.
Other reported adverse effects follow
- Cetylpyridinium chloride may cause extrinsic tooth stains.
- Triclosan has been reported to cause desquamation.
- Sodium hypochlorite has a ‘bleach taste’ and may cause extrinsic brown tooth stains and a burning sensation.
- Hydrogen peroxide can cause oral dryness, taste disturbance, diffuse mucosal whitening and elongation of the filiform papillae (hair-like structures on the surface of the tongue).
- Anti-bacterial peroxidases tend to be acidic, with a pH of around 5.15, increasing the potential for dental erosion, especially with long-term use.
Contraindications and precautions
- Mouthwashes are contraindicated in those who have allergic or hypersensitivity reactions to an ingredient.
- They are contraindicated in children under six years of age, due the risk of swallowing the mouthwash.
- Iodine-containing mouthwash is not recommended for people with hyperthyroidism or other thyroid diseases, due to possible systemic absorption of iodine.
- Long-term use of mouthwash is not recommended.
- The association between long-term use of alcohol-containing mouthwash and increased risk of oral cancer is controversial.