Women are taking Mucinex to get pregnant. Does it work?

The journey to get pregnant can be a long road for many women, some of whom are sharing that they found unlikely help from an over-the-counter cough and cold medicine.

The hashtag #mucinexdpregnancy has over 1,500 posts on TikTok from women claiming the medication Mucinex helped them get pregnant.

"I tried the Mucinex hack [and] it worked!," one TikTok user captioned a post with more than 1 million views. "After 5 months of trying gave it a shot [and] got pregnant first try."

"Trying to conceive for years just to take Mucinex and get pregnant," another TikTok user captioned a viral video with 2 million views.

According to people sharing their stories on social media, taking a Mucinex pill every day during their high-fertile window helped them get pregnant.

"Good Morning America" spoke with board-certified OB-GYN Dr. Jessica Shepherd to break down the trend and whether it's research-proven to work.

Why would Mucinex help with pregnancy?

Mucinex contains an active ingredient, guaifenesin, that helps with congestion by thinning phlegm, a type of mucus produced by the respiratory system.

The theory in using Mucinex to help with fertility is that guaifenesin could also help thin cervical mucus, making it easier for sperm to reach an egg during fertilization, according to Shepherd.

In addition to Mucinex, guaifenesin is also an active ingredient in other over-the-counter cough and cold medications.

"The reason why people think that this is going to be a way that's going to help increase chances of fertility is that the actual medication is going to thin secretions," Shepherd said. "Now, when we think of thinning secretions, we are usually looking at it from a perspective of cervical secretions."

Is there any research proving Mucinex can help with fertility?

Not really, according to Shepherd.

"When we actually look at the data and the studies that have been done on Mucinex and fertility, we know that it hasn't significantly improved the quality of cervical mucus, which could, again, help with some of the motility of the sperm getting to the egg," she said. "However, it is, again, something that women can try on their own, but there is no strong data that's going to say that it's significantly going to increase their chances of fertility."

The most frequently-cited study is one published over 40 years ago in 1982, in a journal entitled Fertility and Sterility. In the study, which included 40 couples over a span of 10 months, the female was given 200 mg guaifenesin three times daily from day five of her menstrual cycle through when she was ovulating. Scientists studied how well the sperm moved through her cervical mucus after using the guaifenesin.

Of the 40 patients, two-thirds showed some improvement in sperm motility. Fifteen of the 40 couples became pregnant during the study, though their pregnancies cannot attribute that solely to guaifenesin.

More recently, in 2010, a case study showed anecdotal evidence of improvement in one patient's sperm count and motility after taking guaifenesin 600 mg extended release tablets twice a day for two months.

However, the study's researchers said it was "not clear" why the patient had improvement and that more research on guaifenesin and male fertility was needed.

What does the maker of Mucinex say about taking it for infertility?

Reckitt, the maker of Mucinex, told "GMA" in a statement that taking the medication for infertility is considered "off-label use."

"Reckitt is aware of recent social media activity surrounding Mucinex and fertility, and we understand why there is heightened interest in this topic. As a global leader in health and hygiene, it is important that we clarify that Mucinex should only be used as intended in line with label directions. Taking Mucinex for infertility constitutes off-label use," the company said in a statement.

"Taking any medications outside their approved indications or without acknowledging all active ingredients may be harmful. In case of doubt, we recommend women have a discussion with their healthcare professional. Please always read the label and safety information before taking any self-care medication."

Is guaifenesin safe to take during pregnancy?

Guaifenesin is considered pregnancy category C by the U.S. Food and Drug Administration.

That classification means means there's no data on human fetuses and studies on animal fetuses showed adverse effects.

Women who are pregnant or are trying to become pregnant should always check with their medical provider before taking any medication.

What causes infertility?

Female fertility is known to decline with age as well as smoking, excessive alcohol use, obesity, low body weight and excessive physical or emotional stress.

Medical conditions that impact the ovulation cycle, uterus, fallopian tubes and ovaries can also contribute to infertility, according to the Centers for Disease Control and Prevention.

Shepherd said it is important that women talk with their doctor if they have concerns about infertility, which is defined by the CDC as being unable to get pregnant after one year of trying or after 6 months if 35 years or older.

"When we look at the different trends that we may see on social media ... I think that is so important for every woman to take into account that they need to discuss this specifically with their doctor to ensure that it doesn't cause any harm, but also that they are following recommended ways for them to improve their chances [for pregnancy] in health and wellness," she said.

Roshan Nebhrajani Bransden, M.D., a family medicine resident physician and a member of the ABC News Medical Unit, contributed to this report.