An "unexpected medical issue" has taken Aerosmith off their scheduled tour. Steven Tyler announced via Twitter that the band would cancel upcoming shows in Curitiba, Brazil; Santiago, Chile; Rosario, Argentina and Monterrey, Mexico.

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On the band's website, Tyler asked fans for patience and reassured them by saying, "I am not in a life threatening condition, but I need to deal with this right away, and get some rest and medical care immediately..."

Doctors advised him not to travel or perform due to the necessity of this need for "immediate" care.

The 69-year-old singer-songwriter is known as the Demon of Screamin' for his high energy. physically demanding onstage acrobatics and enthusiastic shrieks, shrilling, and groans that would easily tax the lungs of the average Sunday morning choir singer into submission.

Speculation regarding his health ranges from throat issues to a possible hernia.

Steven Tyler led an adventurous and spirited experimental period of self-discovery in his own life with drugs and alcohol in the late '70s early '80s period, while the band's popularity waned for record execs and audiences.

Both he and band-mate Joe Perry, who called themselves the Toxic Twins, sought and completed a drug rehab program in 1986, and re-emerged in the national musical consciousness of record buyers with their successful collaboration in '87 with the rap group Run-DMC in a funky re-cut of the Aerosmith hit "Walk This Way".

As for the unpublished health issue, Tyler assured fans: "I promise I'll be back."