Most delirium lasts a few days. In some people it lasts weeks or months, and thinking can take longer to recover than the body.
Most delirium clears within days once the cause is treated. Some people take a week or two. Others improve slowly over weeks or months. This is more likely in older people and in people with dementia.
Delirium that carries on for a long time is called persistent delirium. It still needs treatment and support.
Good days and bad days
Delirium comes and goes through the day. A clear morning does not mean it has gone. A bad evening does not mean things are going backwards. Judge progress over days, not hours. Delirium is usually worse in the evening, and there is more about why the evenings are worse.
The body often recovers before the mind
Someone can be walking and eating normally while still muddled, or clear in their thinking but worn out by a shower. Tiredness and poor concentration are common for some weeks after the confusion itself has cleared. There is more about what to expect after delirium.
When to ask for a review
Ask for a review if the confusion is not improving week by week, if it improves and then gets worse again, or if the person is more confused than they were before they went into hospital. Ask the ward team, or the GP once the person is home. If there is no improvement at all, that is a reason to look again for a cause that has been missed.
Nobody can give you a date for recovery. But slow improvement is still improvement.
When to get help
New confusion that has come on over hours or days needs medical advice the same day. Phone the GP practice, or 111 when it is closed. Phone 999 if the person cannot be woken, has collapsed, or has new weakness or new trouble speaking. When you speak to someone, say what has changed. Then ask: could it be delirium?