Probiotics Side Effects and How to Manage Them

Probiotics, frequently called 'good' bacteria, are intended to provide benefits to the gut microbiome, which plays an important role in our body by interacting with the neural, endocrine, and immune systems. Health-conscious individuals have started to take probiotics, either in their natural form, present in fermented foods, or as supplements, to promote digestive health. While probiotics are overall safe to consume and potentially bring benefits, they can also cause side effects.

Here, we discuss the probiotics side effects and how to manage them.

Potential side effects of probiotics

The most common probiotics, such as Bifidobacterium and Lactobacillus strains, might have far-reaching positive effects on various aspects of health. However, they can come with some side effects. These are more common when probiotics are taken in excessive amounts and less common when used in moderate, recommended amounts.

Digestive issues

Probiotics are frequently used to alleviate certain digestive issues, such as antibiotic-associated diarrhea or irritable bowel syndrome. However, taking probiotics might also lead to several gastrointestinal issues. The most common side effects of probiotics include stomach cramps, bloating, and gas. These frequently occur when you start taking probiotics as the body adjusts to the new bacteria. Probiotics change and rebalance the gut microbiota, which might consequently lead to changes with regular bowel movements, leading to either diarrhea or constipation.

If you start taking probiotics and want to reduce the potential digestive issues, it is worth discussing probiotic supplements with your healthcare provider. They might help you select the right strain that is compatible with your needs. Aim to introduce probiotics gradually into your diet, allowing your digestive system to adjust. Stay hydrated and include gentle movement to alleviate symptoms such as bloating or constipation.

Possible allergic reactions

Probiotics, as any other food supplement, can sometimes cause allergic reactions. Severe allergic reactions to probiotics are very rare, and they are usually associated with the presence of hidden allergens in food and cross-contamination of probiotics with milk or egg, which might be harmful to individuals allergic to these foods.

Mild allergic reactions include rash, itching, or swelling. For instance, one study has shown that probiotic supplementation of infants with L. acidophilus made the children more sensitive to certain allergens.

It is worth noting that certain strains present in probiotics are capable of producing histamine. Histamine regulates certain functions in the gut and acts as a neurotransmitter. The body also produces histamine when its immune system detects a threat. The excess of histamine, which the probiotics might cause, might trigger similar symptoms to allergy.

If you experience allergic reactions to probiotics, it is worth consulting with a healthcare provider. They might recommend discontinuing the use of a specific strain of probiotics or taking antihistamines to reduce symptoms. The side effect management might also include topical treatments or cold compresses, which might help reduce itching and rash sensations.

Headaches

There are several contradictory research studies regarding whether taking probiotics can cause headaches.

Some strains of bacteria produce histamine, which might contribute to headaches. Histamine causes blood vessels to widen through interaction with H1 and H2 receptors and may contribute to neuroinflammation, which, in turn, can contribute to migraines. Therefore, individuals with histamine intolerances might potentially experience headaches by taking certain types of probiotics, which increase the levels of this molecule in their digestive system.

On the other hand, some studies suggest alleviating headaches and migraines as probiotic benefits. The possible mechanisms are still unclear — one possible explanation is that probiotic supplementation lowers the levels of markers responsible for inflammation.

While headaches can be caused by a variety of factors, opting for probiotics with strains that are less likely to produce histamine and avoid histamine-rich foods may be one of the ways to address it for people sensitive to histamine. Your healthcare provider might recommend taking DAO enzyme supplements, which help break down histamine. Aim to drink plenty of water and get an appropriate amount of sleep to reduce the likelihood of headaches.

Risk of infection

Probiotics are considered safe for generally healthy individuals. However, according to the joint report of FAO and WHO, taking probiotics might not be universally effective and safe for individuals with underlying medical conditions. The work reports the cases from the past where immunocompromised individuals suffered from systemic infections.

The meta-analysis published in Microorganisms summarized the exceptionally rare infections caused by probiotics. These include sepsis (a severe response of the body to infection), endocarditis (heart infection), and abscesses (pus that form in tissues and organs). These infections were observed in individuals with weakened immune systems, including patients diagnosed with AIDS and patients receiving chemotherapy. Several cases also include premature babies, newborns, or elderly people.

The immunocompromised individuals are more prone to potential risks of introducing pathogens, including probiotic strains. Therefore, people with underlying medical conditions should discuss the use of probiotics with healthcare providers.

Possibly increased risk of SIBO

Small intestinal bacterial overgrowth (SIBO) is a condition characterized by the abnormal growth of bacteria in the small intestine, which normally contains fewer bacteria than the large intestine. It frequently occurs in patients with irritable bowel syndrome (IBS). While probiotics are known to alter the bacterial gut flora, current research does not clearly indicate whether probiotics might have positive or negative effects on SIBO.

One study evaluated the effect of probiotics in 30 patients experiencing brain fogginess, along with symptoms of abdominal bloating, pain, and gas. The study possibly links these symptoms to probiotic use and SIBO. The symptoms experienced by patients were reduced after stopping probiotics and using antibiotics. Further studies with a higher number of participants and without the administration of antibiotics are needed to confirm the relationship between probiotics and SIBO.

It is worth highlighting that there are multiple studies suggesting the positive effects of probiotics on patients with SIBO. The meta-analysis published in the Journal of Clinical Gastroenterology has indicated that probiotics might reduce bacterial growth in patients with SIBO and alleviate their symptoms.

Antibiotic resistance

Antimicrobial resistance occurs when bacteria and other types of germs develop mechanisms that protect them against the effects of medications, making the treatments ineffective.

Some probiotics, such as Lactobacillus species, contain genes that make them naturally resistant to certain types of antibiotics. Probiotics are considered 'good' bacteria, and therefore, containing these genes does not cause any direct harm. However, once consumed, these genes can sometimes be transferred to 'bad' bacteria present in the gut. If these bacteria get certain genes linked to antimicrobial resistance, they also become resistant to antibiotics, making infection treatment harder.

If you are prone to digestive tract infections, you might consult with a healthcare professional to determine which probiotic is right for you. Aim to source probiotic supplements from known and reputable providers. This will help ensure that the products meet health and safety standards.

Who should avoid probiotics?

While probiotics enhance digestive health and immune function and may provide certain mental health benefits, they might not be suitable for everyone. Certain groups of people might avoid using probiotics or should do so only after consulting with a healthcare professional. These include:

• Individuals with weakened immune systems. People with AIDS, cancer patients undergoing chemotherapy, organ recipients, or patients on immunosuppressive medications should discuss probiotic supplementation with a medical professional. This is because they are more susceptible to infections. These infections can be caused directly by probiotics or through the transfer of antimicrobial resistance genes from probiotics to harmful bacteria, making these bacteria harder to eliminate and potentially more dangerous.
• Individuals with severe illnesses or critical conditions. Taking probiotics might not be suitable for patients after major surgeries, those who have invasive devices, or those who are critically ill. These individuals might have weaker immune systems and compromised physical barriers, which might lead to higher infection risk.
• Breastfeeding and pregnant women. There is limited research regarding the effects of certain probiotic strains on these individuals. Only probiotics that have been tested for these groups should be taken, and only after consulting with a healthcare provider.

Drug interactions

Since probiotics influence gut microbiota, they might also alter the adsorption and composition of certain drugs. The review published in Biomedicine & Pharmacotherapy has summarized the known interaction of probiotics with drugs. The data comes from either animal or human studies, and the drugs that can be potentially influenced by probiotics include:

• Disease-modifying anti-rheumatic drugs (DMARDs) (e.g., Sulfasalazine)
• Central nervous system (CNS) drugs (e.g., Nitrazepam and Clonazepam)
• Antidiabetic drugs (e.g., Gliclazide)
• Cardiovascular drugs (e.g., Amiodarone, Amlodipine, and Nifedipine)
• Cholesterol-lowering drugs (e.g., Simvastatin, Rosuvastatin)
• Immunosuppressive drugs (e.g., Tacrolimus, Acenocoumarol, and Irinotecan)
• Non-steroidal anti-inflammatory drugs (NSAIDs) (e.g., Diclofenac, Ketoprofen, and Paracetamol)

How to minimize side effects

While taking probiotics might lead to certain side effects, you might take these steps to reduce the risk of their occurrence or their effects and enhance probiotic safety:

1. Consult a healthcare professional. If you plan to introduce changes to your diet and consume more probiotic-rich foods or probiotic supplements, it is worth speaking to a doctor or a dietitian. They might help you select probiotics with bacterial strains suitable for your needs and health conditions.
2. Start slowly and be consistent. To help your digestive system adjust, start with a lower dose of probiotics and increase it gradually. Aim to take probiotics at the same time of the day to help your body adjust and maintain a normally functioning gut.
3. Keep a healthy diet and stay hydrated. A well-balanced fiber-rich diet is important to maintain gut health and avoid the potential side effects of probiotics. Aim to take probiotics alongside food as this might help you buffer the stomach. Remember to stay hydrated — drinking plenty of water will help alleviate potential constipation.
4. Keep track of adverse reactions. Aim to monitor potential adverse reactions that you experience while taking probiotics. These observations might help you adjust the strain and dosage of probiotic intake together with your healthcare practitioner. If adverse reactions persist, consult with your healthcare provider for further guidance.

Final word

Taking probiotics can provide several benefits for gastrointestinal health and immune function. However, like any other supplements, they might cause certain side effects when taken in excess or by individuals with impaired immune systems or histamine intolerances.

If you aim to introduce probiotics into your diet, it is good to discuss this with your healthcare provider. They will help you select probiotics with bacterial strains that meet your dietary needs and health conditions. Remember to combine probiotic supplements with wellness practices such as a well-balanced diet, hydration, and exercise.