Is it possible to overdose on probiotics and what are the side effects of taking too much? Probiotic dosages are measured in CFUs or “Colony Forming Units”. This refers to the number of live, viable cultures provided per serving in a probiotic supplement.
Most high-quality probiotics provide between 5 billion to 10 billion CFUs per serving. A dosage of no more than 30 billion CFUs per day is recommended.
These numbers may seem high, but there are trillions of these microbial living organisms currently colonizing your gastrointestinal tract. Supplementing with up to 30 billion CFUs is not likely to dangerously increase your gut microflora populations in a way that could cause “overdose” symptoms.
Probiotic supplements can cause side effects and these side effects may increase in frequency or severity if excess dosages are used. But there have been no reported cases of a probiotic overdose and most healthy adults experience very few adverse effects.



- Supports a healthy immune system & microflora
- Promotes digestion & nutrient absoprtion
- Combats pathogenic bacteria; Improves metabolism
Probiotics Overdose Risks
Related Topics
- What are Probiotics?
- Probiotic Benefits
- Best Probiotic Strains
- Probiotic Side Effects
- Probiotic Supplements
- Probiotic Foods
- Best Probiotic Yogurt
- Probiotics for Children
- Probiotics for Women
- Yeast Infections
- What are Prebotics?
- Lactobacillus Acidophilus
- Lactobacillus Bulgaricus
- Lactobacillus Rhamnosus
- Bifidobacterium Bifidum
- Bifidobacterium Infantis
- Bifidus Regularis
What are the negative side effects possible when using excessive dosages of probiotic supplements?
Probiotics from the Lactobacilli and Bifidobacterium families are rated as Likely Safe when used orally and appropriately. Many use these supplements and experience no negative effects. However, some may experience gas, bloating, diarrhea or digestive discomfort.
These side effects are more common when first beginning to use a probiotic supplement and tend to dissipate after a few days of use. However, taking more than the recommended dose of probiotics could exacerbate these conditions, particularly that of intestinal gas.
If you do take a large dose of Lactobacillus acidophilus probiotics or some other species, the most likely outcome is that you will expel the excess colonies in your next bowel movement. Research shows that consuming Bifidobacteria probiotics results in increased Bifidobacteria in fecal matter.
As such, the risk of overdose is low for healthy adults using probiotics from the Lactobacilli and Bifidobacterium families. These species of probiotics are the ones most commonly found in dietary supplements.
Health Dangers of Probiotics
There is, however, a risk of more serious side effects when probiotics are used by people with certain health conditions. Individuals who are immunocompromised, have Short Bowel Syndrome, catheters or open surgical wounds should avoid taking probiotics unless directed by a medical physician.
For those on immune suppressive medication or for organ donor patients, probiotics are not recommended. The reason for this is because the immune impaired body system is not able to process the healthy bacteria and there is a risk of transmigration and potentially infection.
People with pancreatitis, those in the ICU (Intensive Care Unit), people with Short Bowel Disease (SBS) or are those using a catheter should also avoid using probiotics.
This supplement is also not recommended for those with Melaena (upper gastrointestinal bleeding with dark tar like stools).
There is also a condition known as D-Lactic Acidosis that can occur when taking L. acidophilus probiotics. This condition is usually associated with SBS.
Side Effects of Too Much Lactobacillus Probiotics
Each probiotic culture has different properties. Using probiotics in the recommended doses are beneficial for increasing the friendly bacteria microflora balance
No cases of infections have been reported in the 5 – 30 billion CFU dosage range for those with healthy immune systems. But higher doses could result in some negative effects for individuals with pre-existing health conditions.
Severe complications and deaths have been reported in those with immune suppressed conditions such as organ donor patients and catheter users. Other chronic conditions such as Diabetes may also react adversely to large probiotic dosages.
It is believed Lactobacillus may affect insulin sensitivity. People with Diabetes should be under medical supervision when taking probiotics.
Asthma medications may also interact with Lactobacillus as well as ulcer agents such as Rabeparazole and anti-virals.
According to the Mayo Clinic website, potential side effects may occur if a fever is present when using L. Acidophilus probiotics. Large doses may also cause tooth decay in those with braces.
People who are allergic to milk products should avoid milk based probiotics. There is also a concern Lactobacillus may also interact with arthritis medication, birth control, calcium supplements, and heart medications. There may also be interactions with medications that lower cholesterol, iron salts, ulcer medication and vaccinations.
Probiotic Overdoses and D-Lactic Acidosis
The condition of D-Lactic Acidosis is a condition caused by an overdose of probiotics says Dr. A Maxwell of the website, Ask Dr. Maxwell.
This condition happens when the body is unable to process D-lactate in the probiotic L. acidophilus. This condition may develop with SBS (Short Bowel Syndrome) or when there is intolerance of carbohydrates and after gastrointestinal surgery.
When the body is unable to get rid of the D-lactate it has a neurotoxin effect on the body. Some of the symptoms of D-Lactic Acidosis include headaches, feeling nauseous, and being pale, (pallor).
Other symptoms include craving carbohydrates, having difficulty concentrating, slurred speech and trouble walking and moving hands and arms. There may also be a feeling of weakness, painful muscle spasms and feeling agitated. Teeth grinding and hyperventilation are also symptoms of this condition.
If experiencing any of these symptoms, it is best to discontinue the probiotic straight away. To prevent this condition, avoid L. acidophilus only products which are more likely to cause this condition.
SBS causes difficulties in digesting carbohydrates, electrolytes, fats, fluids minerals and proteins. Symptoms of this condition are diarrhea, dehydration, acid and base and nutritional deficiencies.
This condition permits acid-resistant Lactobacilli to grow and ferment. This process produces D and L-Lactase. When the D-Lactase acid is not able to be processed it builds up in the blood and acidemia and metabolic acidosis happens.
To treat this condition, bicarbonate and fluid infusions are administered. Carbohydrates are avoided in the diet and oral non-absorbent antibiotics are given. This condition can be avoided by only taking probiotics that produce L-lactate.
Saccharomyces Boulardii Overdose
Probiotics overdose is a concern for those taking large dosages of the probiotic Saccharomyces boulardii which may cause constipation.
Saccharomyces boulardii is a is a tropical strain of yeast that exhibits probiotic effects. It may cause yeast reactions in those allergic to yeast. Large doses of this probiotic can also cause temporary constipation.
This probiotic may interact with anti-fungal medications such as Fluconazole (Diflucan), Terbinafine (Lamisil) and Itraconazole (Sporanox). For those with immune impaired conditions this probiotic may cause Fungemia.
It is recommended to avoid this product if you are immunocompromised. Speak to your doctor about the appropriate dosage for S. boulardii to avoid overdose.
Conclusions
Taking larger than recommended dosages of probiotics may cause side effects, especially for those with chronic medical conditions and those on medications. Also the likelihood of side effects such as bloating and intestinal gas increase with larger doses.
Overdoses of Saccharomyces boulardii can cause the symptom of constipation.
Unless directed by a medical professional, probiotics should not be taken by pregnant women or those who are breastfeeding. Antibiotics should be taken two hours apart from probiotics. It is thought prebiotics should also be avoided with SBS.
Probiotics overdose can result in side effects that would not occur if recommended dosages were taken.
- Stadlbauer, V., Immunosuppression and probiotics: are they effective and safe?, Benef Microbes, 2015 Aug 19:1-6. [Epub ahead of print]
- Moroti, C, Effect of the consumption of a new symbiotic shake on glycemia and cholesterol levels in elderly people with type 2 diabetes mellitus. Lipids Health Dis 2012 Feb 22;11:29. doi: 10.1186/1476-511X-11-29.
- Ivey, KL, The effect of yoghurt and its probiotics on blood pressure and serum lipid profile; a randomised controlled trial. Nutr Metab Cardiovasc Dis 2015 Jan;25(1):46-51. doi: 10.1016/j.numecd.2014.07.012. Epub 2014 Aug 1.
- Ivey, KL. The effects of probiotic bacteria on glycaemic control in overweight men and women: a randomised controlled trial. Eur J Clin Nutr 2014 Apr;68(4):447-52. doi: 10.1038/ejcn.2013.294. Epub 2014 Feb 26.
- Alia-Garcia E, Forensic identification in teeth with caries. Forensic Sci Int, 2015 Sep 11;257:236-241. doi: 10.1016/j.forsciint.2015.08.021. [Epub ahead of print]
- Petersen, C, D-lactic acidosis. Nutr. Clin Pract, 2005 Dec;20(6):634-45.
Article last updated on: March 12th, 2018 by Nootriment
1 Comment
I have been taking a probiotic now for acouple months. Was wondering if too much probiotic can harm you. My doctor recommended Floragen3. This internet site helped to answer my question but still have another question. How long should I take Floragen3??