Miley Cyrus has sparked fresh fears for her health after falling sick on tour again.

The Wrecking Ball hitmaker fell ill with a sinus infection earlier this year (14) and subsequently suffered an allergic reaction to her medication, which ended in a hospital stay and the postponement of the remaining dates on her US tour.

Cyrus resumed the trek in Europe last month (May14), but has now worried her fans by revealing she has fallen sick again.

In a post on her Twitter.com page on Monday (09Jun14), she writes, "Sick as a (dog)."

Cyrus is due to perform in Vienna, Austria on Tuesday night (10Jun14), and posted an update just hours before showtime, adding, "Hope I don't suck tonight... still sick."