Probiotics Side Effects: Allergies

Probiotics are considered extremely safe for most healthy people, but it's possible, although rare, to develop an allergic reaction to probiotics or some of the ingredients used in probiotic supplements.

If you do develop an allergic reaction, your symptoms can range from mild to severe.

If you have known food allergies, make sure to read ingredient labels carefully and use caution because some probiotic supplements may contain milk byproducts, like lactose. If you don't have any known allergies but experience an adverse reaction to taking a probiotic, discontinue use and seek emergency medical attention immediately.

Probiotics are supplements that contain helpful bacteria that are naturally found in your gut. According to Harvard Health Publishing, probiotics have been shown to be helpful in alleviating the symptoms of:

• Diarrhea
• Irritable bowel syndrome (or IBS)
• Ulcerative colitis and Crohn's disease
• Vaginal infections, like urinary tract infections (or UTIs)
• Eczema

You can get probiotics in supplemental form, but there are also probiotic foods, like yogurt, miso, tempeh, sauerkraut, kimchi and kombucha that also offer a healthy dose of probiotics.

If you're taking probiotic supplements, it's important to be mindful of the other ingredients. Lots of supplements contain fillers and artificial ingredients that can cause allergic reactions. If you're reacting to a new supplement, it's possible that it's not the probiotic itself, but the added ingredients.

Read more: 13 Surprising and Beneficial Probiotic Foods

Probiotic supplements are manufactured by various brands, each containing varying ingredients, so not every supplement you can buy is the same. Because of this, you may find that you develop an allergic reaction to some probiotics supplements and not others.

One or more of the ingredients in the probiotic supplement can cause your immune system to react as if the body were being attacked by a potentially harmful substance. This confusion causes a chemical release of immunoglobulin E, or IgE antibodies, histamine and other chemicals that cause the characteristic signs of an allergic reaction. The Asthma and Allergy Foundation of America notes that signs and symptoms of an allergic reaction can vary widely, but may include:

• Itchy, watery eyes
  
• Itchy or runny nose
• Rash/hives
  
• Stomach cramps
  
• Vomiting
  
• Diarrhea
  
• Bloating
  
• Cough
  
• Wheezing
  
• Throat tightening
  
• Chest tightness
  
• Light-headedness
  
• Feelings of impending doom/anxiety
  

If you develop one or more of these symptoms, especially throat tightening, trouble breathing and light-headedness, seek emergency medical attention immediately. These may be signs of anaphylaxis, a life-threatening allergic reaction.

Read more: 10 Facts You Need to Know About Food Allergies

It is possible to experience unpleasant side effects to taking probiotics that aren't connected to an allergic reaction. Probiotics side effects are usually mild, buy may include upset stomach, diarrhea, bloating and gas within the first few days after starting a new probiotic regimen, according to Cleveland Clinic.

If you're lactose intolerant you may develop gas, bloating, diarrhea and stomach cramping if you take probiotic supplements that contain milk or lactose, a sugar found in milk that can cause digestive problems for people who can't properly digest it.

If you have a weakened immune system or you're going through chemotherapy, taking probiotics can increase your risk of getting an infection, so you should avoid them or, at the very least, consult your doctor before taking them, even if you're not allergic.