Reigning Miss USA Noelia Voigt has resigned her title, citing mental health reasons.

Ms Voigt, who won the annual competition in September, said she believed in making decisions "that feel best for you and your mental health".

"Never compromise your physical and mental wellbeing," she wrote on Instagram. "Our health is our wealth."

The Miss USA organisation said it supported her decision and would announce a successor.

The 24-year-old Venezuelan-American, of Utah, said she hoped to "continue to inspire others" as she started "a new chapter" in life.

"Prioritise your mental health, advocate for yourself and others by using your voice and never be afraid of what the future holds, even if it feels uncertain," she said.

She expressed her gratitude for her nine months as Miss USA, which she said gave her a "platform ... to make a difference" as well as realise a "lifelong dream" and meet "people all over the world."

Miss USA thanked Ms Voigt and said on Instagram that, "the well-being of our titleholders is a top priority".

The organisation said it was reviewing plans for the "transition of responsibilities to a successor".

Savannah Gankiewicz of Hawaii came second to Ms Voigt in last year's competition.