If you’re a longtime allergy sufferer, you know the intensity of seasonal allergies varies from year to year. And sometimes the things that worked last year to relieve your symptoms — itchy and watery eyes, runny nose, sneezing, stuffy head — won’t work this year. While allergy medications can help, they also have unwanted potential side effects, including dry mouth and drowsiness.

But now, some scientists say, there may be an alternative: probiotics.

Probiotics are live bacteria and yeasts that are beneficial for your digestive system. Though we tend to think of bacteria as something that causes illness, your body contains lots of bacteria, both good and bad. Probiotics are usually called "good" bacteria because they help keep your gut healthy.

Probiotics have gained in popularity in recent years and are sometimes recommended by doctors, especially pediatricians, to counteract a course of antibiotics, which can wipe out the good bacteria with the bad, causing an upset tummy and diarrhea in the process. Probiotics can help combat those gastrointestinal issues.

The two most common types of probiotics are called Lactobacillus and Bifidobacterium. Lactobacillus can be found in yogurt and other fermented foods, such as kefir. It can help with diarrhea and may even help with lactose intolerance. Bifidobacterium also can be found in some dairy products and may be helpful for patients suffering from irritable bowel syndrome (IBS).

Probiotics may be taken as a supplement, too — you may have heard of brands like Culturelle, Florastor and Align.

Early research shows promise

Woman using eye drops Probiotics may change the balance of bacteria in your intestines, which in turn protects the immune system and reduces allergy flare-ups. (Photo: Nicoleta Ionescu/Shutterstock)

During allergy season, allergy sufferers may be heartened to hear that probiotics may help them, as well. A recent study published in the American Journal of Clinical Nutrition suggests that probiotics may help alleviate some of the discomfort. The researchers studied 173 participants who suffered from seasonal allergies. One group was given a placebo and the other a combination of lactobacilli and bifidobacteri (sold as a supplement called Kyo-Dophilus). It should be noted that this study did not include severe allergy sufferers, but the combination of probiotics did show clinical benefit for those with more mild symptoms.

Though the researchers in this study admit they don't quite know exactly how the probiotics relieve allergy symptoms, a 2015 study in the journal International Forum of Allergy & Rhinology may shed some light on the subject.

In that study, researchers compiled data from 23 studies and found that people with seasonal allergies who took probiotic supplements or ate foods containing probiotics showed improvement in their allergy symptoms compared with allergy sufferers who took a placebo. Researchers theorized that the probiotics changed the balance of bacteria in the intestines, which in turn protected the immune system and prevented allergy flare-ups.

"When you look at all the studies combined, there was a statistically significant improvement in both the rhinitis-specific quality of life of those patients and in their nasal specific quality of life,” lead author Justin Turner, M.D., Ph.D., assistant professor of otolaryngology at Vanderbilt University Medical Center in Nashville, said in a press release. But he cautioned that “the jury is still out" and further studies are needed.