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What happens when you first start taking probiotics?

Probiotics are live microorganisms that provide health benefits when consumed in adequate amounts. They can be found in supplement form or in fermented foods like yogurt, kefir, sauerkraut, kimchi, etc. The most common strains of probiotics come from two groups, Lactobacillus and Bifidobacterium. When you first start taking a probiotic supplement or eat more probiotic-rich foods, you may experience some adjustments and reactions in your body as the levels of good bacteria increase. This is completely normal. Here is an overview of some of the effects that can occur when you first increase your probiotic intake.

Possible Digestive Effects

One of the main areas where probiotics make a difference is in your digestive system. As the number of beneficial bacteria increases, you may notice some positive changes related to digestion and regularity. However, you also may experience some mild side effects as your body adjusts. Potential digestive effects include:

– Increased gas and bloating: As probiotics colonize your gut, your intestinal microbiome starts to shift. This can result in more gas production and bloating at first. Staying hydrated and gradually increasing probiotics can help minimize discomfort.

– Mild constipation or diarrhea: Some people become a little backed up or have looser stools when they first take probiotics. This regulates after some time as bowel habits stabilize. Start with smaller doses and work up slowly to reduce adverse effects.

– Stomach pain or cramps: Mild stomach pain is common when you change up your probiotic intake. This should subside quickly. If it persists or worsens, discontinue use and consult your doctor.

– Increased bowel movements: Probiotics may stimulate more frequent bowel movements and detoxification. This regulates with continued use. Drink plenty of fluids.

– Improved regularity and stool consistency: After the initial adjustments, most people notice more regular, well-formed bowel movements from taking probiotics. The beneficial bacteria help stimulate motility.

Possible Immune Effects

Since 70-80% of immune system function happens in the gut, increasing probiotics can also boost immunity. Some of the immune-related changes that may occur when you first take probiotics include:

– Enhanced immune response: Probiotics support healthy immune cells and antibodies. You may notice improved resistance to common illnesses. However, immune changes take time.

– Possible flu-like symptoms: Some people may experience mild “die-off” symptoms like body aches or low fever as probiotics kill off bad bacteria. Drink plenty of water and reduce dosage if needed.

– Improved allergy symptoms: By reducing gut inflammation and stabilizing mast cells, probiotics can minimize seasonal allergy issues like runny nose, itchy eyes, and sneezing. Effects are most notable after 1-2 months.

– Reduced inflammation: Key strains of probiotics help lower systemic inflammation, which can relieve joint pain, skin conditions, and autoimmune disease flares. Anti-inflammatory effects are dose-dependent.

– Faster recovery: With supported immunity and reduced inflammation, you may recover more quickly from colds, the flu, allergies, infections, and injuries when maintaining a high probiotic intake.

Potential Effects on Metabolism and Weight

Your gut microbiome also plays an important role in nutrient absorption, metabolism, and body weight regulation. Taking probiotics may influence these processes:

– Improved digestion and absorption: Probiotics can help you properly digest and assimilate nutrients from your diet due to beneficial enzyme production.

– Healthy weight maintenance: Probiotics promote glucose and fat metabolism, which helps maintain a healthy BMI and prevents obesity. Effects are modest though and take weeks.

– Reduced sugar cravings: By balancing blood sugar control, probiotics can reduce cravings for sweets and carbs. This promotes weight loss and management.

– Healthier cholesterol levels: Probiotics have been shown to lower LDL cholesterol and raise HDL cholesterol for heart health. Check with your doctor if on cholesterol medication.

– Better vitamin production: Probiotics facilitate the synthesis of important B vitamins and vitamin K, improving nutritional status. Test levels after 3-6 months.

Emotional and Psychological Effects

Your gastrointestinal microbiome also communicates directly with your brain through the gut-brain axis. Taking probiotics can influence mood, stress response, and mental health by:

– Decreased stress and anxiety: Key probiotic strains can lower cortisol and calm nervous system activity to reduce daily stress and worry. Effects are often noticeable within the first month.

– Improved mood and outlook: By synthesizing key neurotransmitters and lowering inflammation, probiotics can boost mood and ease sadness or depression. You may feel more optimistic.

– Enhanced sleep quality: Probiotics improve sleep duration, depth, and REST by influencing serotonin and GABA neurotransmitter activity. Most people notice easier, higher quality sleep.

– Heightened mental clarity: When gut inflammation is lowered, communication improves between the gut and brain. This can support focus, concentration, and cognitive function.

– Neuroprotective effects: Probiotics may counter oxidative stress in the brain, which can offer protection against dementia, Alzheimer’s disease, Parkinson’s disease, and strokes over time.

How Long Do the Effects Last?

Most of the symptoms you experience when first starting probiotics should subside within 1-4 weeks as your microbiome rebalances. Digestive symptoms tend to resolve more quickly, while benefits like allergy relief, weight loss, and mood support are gradual and take 3-6 months of daily probiotic intake. To maintain these positive effects long-term, you need to keep consuming probiotics through fermented foods, yogurt, kefir, kombucha, or a daily supplement. If you stop taking probiotics, your gut microbiome will eventually shift back towards imbalance and inflammation and symptoms may return.

Tips to Minimize Discomfort When Starting Probiotics

Here are some tips to help ease the transition when you begin taking probiotic supplements or ramp up probiotic foods:

– Start slowly – Begin with smaller doses like 5-10 billion CFUs and gradually increase over 2-3 weeks

– Take with food – Consuming probiotics with meals can minimize side effects

– Stay hydrated – Drink plenty of water and fluids to support detoxification

– Take at night – Taking probiotics before bed allows your body to adjust overnight

– Reduce sugar intake – Limit added and refined sugars to avoid feeding bad bacteria

– Get enough fiber – Eat plenty of prebiotic fibers from veggies, fruits, nuts and seeds

– Try different strains – Rotate different probiotic strains to diversify gut bacteria

– Be patient – Give your body at least 4 weeks to adjust and rebalance

Are Side Effects Dangerous?

For most healthy people, the transient side effects that can occur when first starting probiotics are more of a nuisance than a serious problem. They typically resolve quickly with continued use. However, some people with certain medical conditions should use probiotics with caution and under medical supervision:

– Immune disorders like HIV/AIDS or lymphoma
– Organ transplant recipients taking immunosuppressant drugs
– Patients undergoing chemotherapy or radiation
– Critically ill patients
– People with catheters or other implanted medical devices
– Those with short bowel syndrome or other GI absorption issues
– Individuals with acute pancreatitis or small intestinal bacterial overgrowth (SIBO)

For people with compromised immune function, probiotics could potentially lead to dangerous systemic infections. Those with GI absorptive disorders like SIBO could develop sepsis when taking oral probiotics. Consult your physician before starting any probiotic if you have a serious medical condition or take immune suppressing medications.


When introducing probiotic foods and supplements for the first time, it’s normal to experience some mild digestive, immune, or neuro-emotional changes as your gut microbiome rebalances. Bloating, gas, upset stomach, constipation, or diarrhea are common. You also may notice enhanced immunity, improved mood and cognition, healthier bowel function, and metabolic benefits over the first few weeks. To minimize discomfort, start with lower doses, take with food, stay hydrated, and gradually increase intake. Most symptoms should subside within 1-4 weeks. Give probiotics at least 3-6 months to have a notable impact on your overall health and wellbeing. With the right combination of probiotic strains and persistence, you can achieve optimal digestive, immune, hormonal, and mental health through a well-balanced gut microbiome.