The Queen's sickness was first announced on Friday, and she spent yesterday resting at Windsor.
Her Majesty had been due to attend a Welsh military celebration in Swansea during the country's St David's Day celebrations on Saturday, but was forced to cancel the plans.
The Queen, who is 86, has undertaken a number of engagements during the last week.
On Tuesday she met the Archbishop of Canterbury at Buckingham Palace, and on Thursday she presented a host of Olympic stars with honours during an investiture ceremony.
More top news
The foreign secretary's suggestion last week's bombing of an aid convoy might constitute a war crime prompted an angry response from Moscow.
Goals from Charlie Austin, Dusan Tadic and James Ward-Prowse consigned Slaven Bilic's men to their fourth straight Premier League loss.
Showers will continue in the north and west, heavy in places.