Justin Timberlake has been diagnosed with Lyme disease, the popstar announced on Instagram.

Timberlake shared the news in a post commemorating his Forget Tomorrow tour, which wrapped in Turkey on Wednesday after more than 120 shows around the world.

The singer described the tour, which lasted for over a year, as “the most fun, emotional, gratifying, physically demanding, and, at times, grueling experience.”

He said that living with Lyme disease “can be relentlessly debilitating, both mentally and physically”, adding that learning about the diagnosis was a shock.

The former NSYNC star, who described himself as a private person, wrote he considered ending the tour when diagnosed, but that he “decided the joy that performing brings me far outweighs the fleeting stress my body was feeling. I’m so glad I kept going.”

Lyme disease is transmitted by Ixodes ticks, also known as deer ticks. It can cause flu-like conditions, neurological problems, joint paint and other symptoms. The first sign is often a red, round bull’s-eye rash.

Untreated Lyme can cause severe arthritis and damage the heart and nervous system.

In the vast majority of cases, Lyme disease is successfully treated with antibiotics.

Living with Lyme disease “can be relentlessly debilitating”, Timberlake said on Instagram – Instagram/@justintimberlake

“I honestly don’t know what my future is onstage, but I’ll always cherish this run! And all of them before! It’s been the stuff of legend for me,” Timberlake wrote.

Timberlake cancelled and postponed multiple shows throughout the tour’s run, citing health issues including bronchitis and laryngitis.

Timberlake ultimately cancelled the last show of the US leg of the tour in Ohio due to the flu in February.

The 10-time Grammy winner ended the post thanking his wife, Jessica Biel, and their two sons, Silas and Phin, saying “nothing is more powerful than your unconditional love. You are my heart and my home. I’m on my way.”

Many celebrities have spoken up about their experience with Lyme disease in recent years, including comedian Amy Schumer and singers Justin Bieber and Shania Twain.

Former Real Housewives of Beverly Hills star Yolanda Hadid has become a major voice on the issue after she said she was diagnosed with chronic Lyme disease in 2012.

She later revealed two of her children, models Bella and Anwar Hadid, suffered from the same illness.

There is no scientific consensus over whether a chronic form of Lyme disease actually exists. The US Centers for Disease Control and Privention (CDC) “discourages use of the term Chronic Lyme Disease” as the cause for prolonged symptoms is not currently known.

Hadid released her memoir “Believe Me: My Battle with the Invisible Disability of Lyme Disease” in 2017.

“This disease has brought me and many others to our knees, often wishing to die of utter hopelessness and exhaustion”, she said in a speech at the 2016 Global Lyme Alliance Gala in New York.

The CDC cites insurance records suggesting 476,000 people are treated for Lyme disease in the US each year.