The redness drew widespread attention on Monday, when news photographers captured close-up images of the president's neck during a Medal of Honor ceremony in the East Room of the White House.
"President Trump is using a very common cream on the right side of his neck, which is a preventative skin treatment, prescribed by the White House Doctor," Sean Barbabella, the president's doctor, said in a statement.
"The President is using this treatment for one week, and the redness is expected to last for a few weeks."
In October Barbabella issued a statement saying Trump "continues to demonstrate excellent overall health".
The White House did not immediately respond to follow-up questions, such as what the cream is, when Trump began the treatment and what condition it is supposed to prevent.
Zoomed-in photos from at least as far back as the Board of Peace meeting at the US Institute of Peace on February 19 show visible redness on the president's neck.
The president's medical report from his April 2025 physical noted that he was taking mometasone cream "as needed" for an unspecified skin condition.
Trump, 79, became the oldest president to have taken the oath of office when he was sworn in last January. In particular because of his advanced age, Trump's health is closely scrutinised.
Barbabella said in December that Trump had MRI imaging on his heart and abdomen in October as part of preventive screening for men his age, with the results being "perfectly normal".