Crown Princess Mette-Marit of Norway is to start a new course of treatment for a chronic lung condition.
The Crown Princess, 51, will begin the process immediately.
The future queen was diagnosed with chronic pulmonary fibrosis in 2018.
The royal court said that, as has happened with past treatments, the drugs involved may lead to side effects that could impact on what the Crown Princess is able to do in the coming weeks and months.
Her diary will be subject to very short term change and royal officials said it was therefore normal to share the news of this latest round of treatment.
When the Crown Princess announced her diagnosis, in October 2018, she confirmed that her royal work would be impacted and that she might have to miss engagements at short notice as her health was monitored. She has also reduced the number of events she attends in the years since her condition was first discovered.
Earlier this week, the Crown Princess of Norway took part in several engagements for World Mental Health Day, including a visit focused on good mental health for young people.
