Miley Cyrus could be out of action for up to a month as she struggles to recover from an allergic reaction to antibiotics.

The pop star has axed two shows after she was hospitalised in Missouri on Tuesday (15Apr14), and now a representative for the Wrecking Ball star has sparked fears more dates on the Bangerz tour are in jeopardy.

Cyrus has suffered an "extreme" reaction to a drug she took to combat a sinus infection, and her spokesperson has confirmed it will be a long and slow recovery for the star.

The representative says, "Miley was suffering from a sinus infection during her tour in N.C. (North Carolina) a week ago. She was prescribed the antibiotic cephalexin, which she has now suffered an extreme allergic reaction to. This type of extreme reaction can last from five to 27 days in these types of cases. She will remain hospitalised and is under a doctor's care until we see some improvement and is asking for your compassion and privacy at this time. Miley is devastated about missing shows and possibly disappointing her fans."

Cyrus has been keeping her fans updated throughout her health crisis, even uploading a picture to showing her lying in her hospital bed.

She writes, "Over the hospital... I miss Bangerz tour... 5am hospy selfie so sleeeeepy (sic)... medz (medicine) time... Can't quit crying... I wanna go back on tour. I'm meant to be onstage performing for y'all... Not laying in a hospital bed."

Cyrus' next planned show is due to take place in Nashville, Tennessee on Friday (18Apr14).