What This Strain Does
Streptococcus salivarius occupies a unique niche in the probiotic world as a specialist of the oral cavity. While most probiotics target the gastrointestinal tract, S. salivarius naturally colonizes the mouth, throat, and nasopharynx—making it the ideal probiotic for oral and upper respiratory health. This bacterium is among the first microorganisms to colonize a newborn’s mouth, typically transmitted from the mother during birth and breastfeeding, and it remains a dominant member of the healthy oral microbiome throughout life.
The probiotic mechanism of S. salivarius centers on competitive exclusion and antimicrobial production. By abundantly colonizing oral surfaces, beneficial strains of S. salivarius occupy ecological niches that might otherwise be claimed by pathogenic bacteria responsible for dental caries, gum disease, bad breath, and throat infections. Additionally, specific probiotic strains produce bacteriocin-like inhibitory substances (BLIS) that directly kill or inhibit harmful bacteria.
Two key antimicrobial compounds produced by probiotic S. salivarius strains are salivaricin A and salivaricin B. These BLIS compounds are active against Streptococcus pyogenes (the bacterium causing strep throat), Streptococcus pneumoniae (a cause of ear infections and pneumonia), and the bacteria responsible for halitosis (bad breath). This targeted antimicrobial activity explains why S. salivarius supplementation can improve oral health outcomes and reduce upper respiratory infections.
Unlike gut-targeted probiotics that must survive stomach acid, oral probiotics like S. salivarius are delivered in formats designed to maximize contact with oral tissues—typically lozenges, chewable tablets, or oral sprays. The bacteria colonize the mouth directly without needing to transit the harsh gastric environment, establishing residence in dental plaque, on the tongue surface, in tonsillar crypts, and throughout the throat.
Research Highlights
Clinical research has validated S. salivarius as an effective oral probiotic across multiple applications:
Halitosis (Bad Breath) Treatment: A randomized controlled trial published in the Journal of Applied Microbiology examined S. salivarius K12 in adults with chronic halitosis. After using the probiotic lozenge daily for 1 week, participants showed significant reductions in volatile sulfur compounds—the chemicals responsible for bad breath odor. Improvements persisted as long as supplementation continued.
Streptococcal Throat Infection Prevention: Research published in the International Journal of General Medicine followed children who received S. salivarius K12 after completing antibiotic treatment for strep throat. Over the following 6 months, children taking the probiotic experienced 90% fewer strep throat recurrences compared to children not receiving the probiotic—a dramatic reduction in this common childhood infection.
Ear Infection Reduction: A clinical trial published in the European Journal of Clinical Microbiology and Infectious Diseases found that S. salivarius K12 supplementation reduced acute otitis media (ear infection) episodes in children with recurrent infections. The probiotic group experienced significantly fewer ear infections and required fewer antibiotic courses over a 6-month period.
Tonsillitis Prevention: Research examining children prone to recurrent tonsillitis showed that S. salivarius BLIS K12 supplementation significantly reduced the frequency and severity of tonsillitis episodes. Some studies suggested the probiotic might reduce the need for tonsillectomy in children with chronic tonsil problems.
Specific Strains to Look For
Two specific strains of S. salivarius dominate the oral probiotic market, each with distinct research support:
S. salivarius K12 (BLIS K12) is the most extensively researched oral probiotic strain, with clinical trials supporting its efficacy for bad breath, strep throat prevention, ear infection reduction, and general oral health. It produces salivaricin A2 and salivaricin B, active against streptococcal pathogens. This strain was discovered by isolating S. salivarius from children who rarely developed throat infections.
S. salivarius M18 (BLIS M18) is specifically researched for dental health applications. It produces salivaricin A and other BLIS compounds active against bacteria involved in dental caries and gum disease. M18 also produces enzymes that help break down dental plaque. Some products combine M18 with K12 for comprehensive oral coverage.
S. salivarius DSM 14685 has been studied for its immunomodulatory properties and appears in some research examining oral microbiome influences on systemic health.
When selecting products, look for these specific strain designations. Generic S. salivarius products without strain identification may not provide the documented benefits.
What to Look For in Products
Oral probiotics have specific formulation requirements that differ from gut-targeted products:
Delivery Format: Lozenges and chewable tablets are the preferred formats, allowing the bacteria to contact oral surfaces during dissolution. Swallowing a capsule delivers bacteria to the gut, bypassing the oral cavity where S. salivarius provides its benefits. Some products use oral sprays for targeted delivery.
CFU Count: Clinical studies have typically used 1-4 billion CFU per dose. Because oral delivery is direct without gastric transit losses, lower CFU counts can be effective compared to gut-targeted probiotics.
Dissolution Time: Effective oral probiotics should dissolve slowly in the mouth (ideally 5-10 minutes) to maximize bacterial contact with oral tissues. Avoid products that dissolve very quickly.
Strain Specificity: Only K12 and M18 strains have the clinical research documenting oral health benefits. Ensure products identify these specific strains.
Timing Recommendations: Most products recommend use after brushing and before bed, allowing the bacteria to colonize overnight without food or drink interference. Some protocols recommend morning and evening dosing.
Minimal Additives: Choose products with minimal sugars and artificial sweeteners, which could counteract oral health benefits. Xylitol is an acceptable sweetener that may provide additional anti-cavity benefits.
Potential Side Effects
S. salivarius has an excellent safety profile, being a normal component of the healthy human oral microbiome. The K12 strain, in particular, has extensive safety documentation including use in children. Potential considerations include:
Initial adjustment: Some users report temporary changes in mouth feel or taste during the first few days of use as the oral microbiome adjusts. This typically resolves quickly.
Rare hypersensitivity: As with any product, rare allergic reactions are possible. Discontinue use if unusual oral symptoms occur.
Ingredient considerations: Check product ingredients for allergens. Some formulations contain dairy-derived ingredients or common allergens.
Not a substitute for dental care: S. salivarius supports oral health but does not replace proper dental hygiene, regular dental visits, or treatment for existing dental disease.
S. salivarius is considered safe for children, pregnant women, and most populations. However, individuals who are severely immunocompromised should consult healthcare providers before use.
How to Take
For Bad Breath: Use one lozenge after brushing teeth, allowing it to dissolve slowly in the mouth. Evening use is typically recommended. Most people notice improvements within 1-2 weeks of consistent use.
For Throat and Ear Infection Prevention: Use daily, particularly during cold and flu season or periods of high exposure risk. Children who have recently completed antibiotic treatment for strep throat may benefit from a course of S. salivarius to prevent recurrence.
For General Oral Health: Use one lozenge daily, preferably in the evening after final tooth brushing. Consistent daily use provides better colonization than intermittent use.
For Dental Health (M18 strain): Use according to product directions, typically once or twice daily. Allow lozenges to dissolve slowly for maximum contact with teeth and gums.
After Mouthwash or Antibiotics: Wait at least 30 minutes after using antimicrobial mouthwash before taking S. salivarius, as antiseptic products can kill the beneficial bacteria. After completing antibiotic courses, S. salivarius can help restore healthy oral flora.
Optimal Timing: Use after brushing and flossing, before bed. Avoid eating, drinking, or rinsing for at least 30 minutes after use to allow bacterial colonization.
Duration: Most clinical studies ran 3-6 months. While benefits may be noticed within weeks, continued use supports ongoing colonization and protection.
Key Takeaways
- Specialized oral probiotic that colonizes the mouth and throat rather than the gut, providing targeted oral and upper respiratory benefits
- Produces BLIS compounds (salivaricins) that kill bacteria responsible for strep throat, ear infections, and bad breath
- Clinically proven to reduce strep throat recurrence by up to 90% in children following initial infection
- Effective for halitosis with measurable reductions in odor-causing volatile sulfur compounds within days
- Reduces ear infections and may decrease the need for antibiotics in infection-prone children
- Requires oral delivery via lozenges or chewable tablets—swallowed capsules bypass the target area
- Look for K12 strain for throat and immune benefits, M18 strain for dental health focus
- Use after brushing and before bed for optimal colonization
- Safe for children and has extensive safety documentation for all ages
- Consistent daily use provides better protection than intermittent supplementation