Pope Francis suffered a dangerous health setback Friday during his weeks-long fight against double pneumonia — causing him to inhale vomit and be placed on a ventilator.

The 88-year-old had a bronchial spasm Friday but responded well to treatment by staying alert and conscious with good oxygen levels during treatment, according to Vatican officials.

The breathing problem marked a “sudden worsening of the respiratory picture” in the afternoon in Rome local time, the officials said.

Doctors are keeping the Holy Father’s prognosis status “guarded,” meaning they’re unsure about the likely outcome of his condition.

But medical experts didn’t use the term “critical condition”— which has been absent from their statements for the past three days —  when referring to his health status.

The scary setback came after two days of increasingly upbeat reports from doctors treating the pope at the Gemelli in Rome, where he was hospitalized on Feb. 14.

Before the bronchial spasm, Francis spent Friday morning on high flows of supplemental oxygen and praying in the chapel. 

He had breakfast, read local newspapers and was receiving respiratory physiotherapy, the Vatican said.

The Vatican has already made alternative plans for Ash Wednesday next week, a sign Francis has a long recovery road ahead of him. 

Cardinal Angelo De Donatis, a Vatican official and former vicar of Rome, will preside over the March 5 ceremony in place of Francis.

The Vatican also changed his upcoming calendar of events by cancelling a Holy Year event scheduled for Saturday.

In past years, when Francis has battled bronchitis and the flu in winter, he curbed his participation in Ash Wednesday and Holy Week events, which call for him to be outside in the cold leading services.

Francis has a few major other events coming up, including the canonization of Carlo Acutis, considered to be the first millennial and digital-era saint, on April 27. The Vatican considers the Italian teenager, who died of leukemia in 2006 at the age of 15, an inspiration for young Catholics.

Another important event is on May 24, when the commemoration of the 1,700th anniversary of the Council of Nicea, Christianity’s first ecumenical council, is scheduled.

Catholic supporters around the world gathered to show support for Francis Thursday.

In Mexico City, a few dozen people flocked to a cathedral Thursday night to pray for Francis’ recovery.

“He is like part of the family,” said Araceli Gutiérrez, who treasures the time she saw the pope during his trip to the country in 2016. “That’s why we feel so concerned for him.”

María Teresa Sánchez, who was visiting from Colombia with her sister, said that she has always felt close to Francis — the first Latin American pope.

“That’s like having a relative within the higher-ups, with God,” she said. “He has done so much for religion; he’s such a humble person.”