Top doctors have weighed in on President Donald Trump's bruised hand after commentators expressed concern over the marking. 

Photos of the yellow and purple bruise emerged after Trump, 78, met with French President Emmanuel Macron at the White House on Monday to discuss a possible end to Russia's war against Ukraine.

A White House official told DailyMail.com that the bruise is from shaking hands with hundreds of people on the campaign trail and in his regular duties. 

Talking to DailyMail.com, Dr Stuart Fischer - an internal medicine physician in New York - said that while an 'aggressive' handshake could partly be to blame, his age may also provide a clue. 

He explained old age naturally weakens blood vessels and makes them more 'brittle,' which makes bruising 'on any part of the body' much more likely and severe. He highlighted Trump is the second-oldest president in US history.

Osteoarthritis, an age-related disease that breaks down cartilage and bone in the joints, could be another possibility, Dr Fischer says, as it can cause easy bruising or discoloration around affected joints in the hand.

'I think it's probably all of those things together,' he said. 

Trump and Macron, 47, awkwardly shook hands three times during their meeting in DC, with the pair even gripping onto each other for a prolonged 12 seconds as they were reunited. 

The duo, whose uncomfortable 'death clasp' handshakes have gone viral over the years, later shared two further awkward physical encounters.

Some social media users accused the White House of holding back information on the president's health.   

'What aren't we being told about his health?' one X user said of Trump's bruise, as another asked: 'Is this why he wouldn't release his medical records?' 

Social media users have flooded X with unsubstantiated theories about Trump's bruise, with the most popular being that it was caused by an IV.

'I think it kinda looks like an IV bruise. Like he's been dehydrated and given fluids. Or maybe he's vitamin deficient?' one user speculated. 'But that's what kind of bruise it looks to be.'

'It appears to be an IV bruise and it happens a lot to Trump. There are a lot of pics with bandages and bruises,' another echoed.

Dr Neal H Patel, a primary care physician at Providence St Joseph Hospital in California, told DailyMail.com the bruise could be from a blood draw or IV infusion poking through weak blood vessels.

One even noted that the bruising 'always seems to be on the same hand'.

Both doctors agreed that while the bruise appears alarming, it's 'unlikely' the president has a serious health condition.  

Dr Fischer said Trump's age is the main risk factor for easy bruising. 

As we age, our blood vessels become less flexible, thicker, and stiffer. This makes it harder for blood to flow through them, resulting in bruising.

Older skin also becomes thinner and loses its protective fatty layer, which makes it show blood vessel damage more easily.

Coupled with Trump's 'aggressive handshake,' bruising is a no-brainer, Dr Fischer said. 

'He doesn't just give a handshake. He's really holding on,' Dr Fischer said. 

He also pointed to osteoarthritis, which affects 32million US adults, the majority of whom are over age 65. 

The tissue that cushions the end of bones, called cartilage, breaks down naturally with age, leading to pain, stiffness, and swelling. 

Along with bruising, Dr Fischer explained osteoarthritis 'would lead to swelling of the digits and the bones in the hand, giving a puffier appearance to them.' 

Dr Patel, on the other hand, agrees with the social media commenters and suggested the bruise could be from an IV needle, which could be from certain medications and infusions. 

IV needles puncture the walls of veins, causing blood to leak out into surrounding tissue. 

However, Dr Fischer said the bruise is 'not in the right place' for it to be from an IV, as there are not enough veins there.   

Dr Patel also rejected the idea that Trump just shakes too many hands. 'I see a lot of patients who are businessmen, and I've never really seen them getting bruising from too much handshaking,' he said.

'I guess it's possible, but that would really not be on my list of ideas of what causes it.'

Dr Fischer said that while the bruise looks grizzly, it isn't a sign of a major health condition. 'I definitely don't think it's any kind of emergency,' he said.