Due to vocal chord strain, R&B singer Jennifer Hudson has been forced to postpone four shows and cancel another on her first official tour of the U.S. in order to give her throat a rest.

Hudson’s May 7 show at the Nokia Theatre in Grand Prairie, TX, just outside Dallas, has been rescheduled for May 16; the May 8 concert at the Verizon Theatre in Houston, TX, has been moved to May 17; and the May 3 performance at the Paramount Theatre in Oakland, CA, has been rescheduled for May 19.

Hudson’s May 5 gig at the Dodge Theatre in Phoenix, AZ, has been postponed, but the make up date has not been released yet.

The Baltimore, MD, show at Pier 6 Pavilion on May 15 has been cancelled according to Hudson’s official Web site, though tickets continue to be sold through Ticketmaster and the venue Web site. She will perform on NBC’s “Today” show that morning, which was on the original itinerary with the Baltimore show.

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Refunds for the cancelled performance will be available at the point of purchase, while tickets holders can use their tickets at the rescheduled performances. Robin Thicke is the opening act on the tour.

Hudson, one of the finalists on “American Idol” in 2004, is on the road promoting her eponymous debut album released in 2008. Before it was released, she won an Oscar for Best Supporting Actress in the 2006 film “Dreamgirls.”