Although probiotics are considered beneficial to health, for some people, initial ingestion of these microorganisms can cause a range of uncomfortable symptoms. When first taking probiotics, some people may experience symptoms such as bloating, diarrhea, headaches, fever, muscle pain, brain fog, and possibly anxiety. These symptoms are thought to be a response to changes occurring in the body, such as the demise of potential pathogens or the reactivation of intestinal responses, a phenomenon sometimes referred to as the "Herxheimer reaction."
The Herxheimer reaction is an initial response that usually indicates the body is adapting to a new microbial environment. This may be due to the probiotics interacting with the existing microbial community, causing the death of the bacteria or the release of metabolites that trigger these symptoms. Although uncomfortable, this reaction is usually short-lived and subsides quickly. It can be thought of as part of the body's process of homeostasis.
This usually affects only a small number of people, with symptoms being mild and usually lasting only a few days to a few weeks. If these symptoms make you uncomfortable, you can reduce your dose or stop using it for a few days before trying again; if these symptoms persist for more than a few weeks, stop using it; if you have shortness of breath, tight throat, hives, or other allergic reactions symptoms, please stop using it immediately. To reduce the possibility of side effects, especially for those with sensitive digestive systems, it is wise to start with a small amount of probiotics and then increase the dose over a few weeks.
Probiotics need to be used with particular caution in those with severe immune deficiencies, as in rare cases, probiotic ingestion may lead to infection. This is because the immune system cannot effectively control the proliferation of microorganisms in the body, causing the risk of infection.
Some people may have allergic reactions to certain types of probiotics, especially yeasts related to Saccharomyces boulardii. Other types of probiotics, such as lactobacilli, generally do not trigger allergic reactions.
Some probiotics can produce histamine in the digestive tract. Excessive histamine release can cause symptoms such as itching, increased tear production, runny nose, difficulty breathing, redness, and swelling, especially for those with histamine intolerance. Avoid these probiotic strains to prevent discomfort.