Here's what we know about how ashwagandha can impact testosterone, libido, and penis size

• Ashwagandha is an herb that may help reduce stress and anxiety.
• Some people on social media claim that can boost testosterone and even penis size.

Ashwagandha supplements, a plant traditionally associated with anxiety and stress relief, have been rising in popularity on social media under a new name: "glizzy pills."

Users are claiming that the herb has a host of sexual wellness benefits, including increased testosterone, higher libido, and even improved penis length.

"Apparently the main thing it's supposed to do is increase your testosterone and decrease your stress levels," said creator Elijah Watz in a TikTok video from 2021. "I guess the big peepee is just a side effect."

Ashwagandha might moderately boost testosterone levels, according to Dr. Adrian Lopresti. Lopresti is a clinical psychologist and managing director of Clinical Research Australia, a company that does clinical research on behalf of sponsors, including supplement companies.

But the biggest body of evidence for ashwagandha is still probably for stress, Lopresti said. Here's what ashwagandha can — and can't — do for your health.

Ashwagandha likely helps the most with stress and anxiety

Ashwagandha, also known as Withania somnifera, is a medicinal herb that's been used for centuries in traditional Ayurvedic medicine.

Some research suggests that it works as an adaptogen — a type of natural remedy that can alleviate stress.

Most research on ashwagandha has been on its anti-stress and anti-anxiety properties, and some studies have found that it does seem to help. However, more research is still needed.

To reap the benefits of ashwagandha, Lopresti said you might need to take it for several weeks. "It's not one that you take today and feel better tomorrow," Lopresti said. "Two to eight weeks is where you probably get the maximum benefits."

Small studies show it could boost sexual wellness

There's some data to show that ashwagandha might help boost testosterone.

Lopresti published a 2019 paper that did find that ashwagandha boosted testosterone levels in healthy men ages 40-70. However, the boost was only moderate, he said.

"It's not steroid-induced testosterone increases, it's still within normal healthy levels," Lopresti said. The study was funded by a company that sells ashwagandha supplements.

This increase in testosterone could be beneficial for otherwise healthy older men, Lopresti said. "Research shows that in men, as we age, testosterone decreases, and having higher levels might be associated with improved health," he said.

One small 2015 study in younger healthy men also found that ashwagandha boosted testosterone levels, and also increased muscle size and strength.

Some additional small studies have found that ashwagandha may increase sperm concentration and motility in men with infertility. While these findings could be promising, more research is needed, Lopresti said.

But these pills aren't magic

But as for penis size, these "glizzy pills" don't seem to make a difference. Two studies from 2011 and 2014 found that ashwagandha had no effect on penis length, circumference, nor do they help with erectile dysfunction.

So while ashwagandha might have some benefits, "it's not a magic pill," Lopresti said. "If people have an unhealthy lifestyle, and they eat unhealthy foods and they don't sleep well, it's not going to fix that."