Mohammed has paid a heavy price for treating the wounded in his home country.
In late 2012, he was working as a field doctor in Damascus when he became the target of a brutal crackdown on those providing medical assistance to the injured in opposition-held areas. "I left Syria after I was detained three times," he told Al Jazeera from his new home in the US.
"In none of the times I was detained I admitted that I was helping people or treating injured civilians, so I could be released," he said. "I was tortured for only being suspected of helping people in need who don't have any access to medical care."
In July 2012, the Syrian government passed an anti-terrorism law that effectively made it a crime to provide medical care to anyone suspected of supporting the opposition.
An investigation by the Human Rights Council concluded last September: "By… targeting medical personnel and interfering with patients receiving treatment, Government forces have perpetrated a concerted policy of denying medical aid to those affiliated with or part of the armed opposition."
Mohammed, who asked that his real name not be used because his family is still in Syria, said he was one of thousands of doctors who were targeted for their work. "At every checkpoint they [the government] were inspecting me just for being a doctor. Many of my friends were detained for having some medication in their cars despite working as medical representatives for pharmacological companies.
"Some of my friends were killed under torture for treating injured people, and others have been detained for longer than 18 months."
Doctors fleeing Syria
Mohammed is one of an estimated 15,000 doctors who have fled Syria in the past three years, according to a recent report by Physicians For Human Rights (PHR). The figure represents half of the certified physicians in a country whose medical system was once touted as the best in the Arab world.
Dr Annie Sparrow, assistant professor of global health and deputy director of the Human Rights Programme at Icahn School of Medicine in New York, told Al Jazeera many doctors left at the beginning of the crisis. "They were under threat, so the easiest thing to do was leave the country," she said. "Even the ones who are left, it is too dangerous for them to get to work."
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Of the 6,000 physicians practicing in Aleppo - the largest city in Syria with a population of 2.5 million - 250 remained as of July 2013, according to the PHR report. In the Damascus suburbs where Mohammed worked, a pre-war figure of 1,000 doctors had been cut down to 30 by last December, the report added.
Doctors aren't the only ones who have fled. Nurses, ambulance drivers and paramedic technicians have also been forced out of the country, unable to provide life-saving medical care because of deliberate and systematic attacks on medical facilities by forces on both sides.
According to the Syrian-American Medical Society (SAMS), 57 percent of hospitals in Syria have been damaged and 37 percent have been rendered completely useless. Seventy percent of health centres in Aleppo, Deir ez Zour, and Idlib governorates have also been destroyed.
As of January 24, 2014, at least 398 medical personnel had been killed since the beginning of the conflict, including 149 doctors and 80 medics, the Violations Documentation Centre in Syria reported.
Most doctors who have fled Syria have gone to Gulf states such as Saudi Arabia, while others choose Turkey, Jordan, Lebanon, Egypt, Libya, Europe and the US, said Dr Zaher Sahloul, a Chicago-based pulmonologist and president of SAMS.
"Most of them will not return - based on previous experience with Syrian diaspora - especially given the security and economic situation will take many years to get back to pre-crisis level," he told Al Jazeera. "The longer the crisis lingers, the more likely that most physicians will not return."
Sahloul said most Syrian doctors in the Gulf were practicing in their chosen field, while those in refugee host countries were predominantly working with NGOs. "Most who left for Europe or the US are trying to settle, apply for asylum and find a job. The lucky ones with US board certifications or European licences are working in their field," he added.
Mohammed, who must first pass certification exams to resume his work, is one of up to 1,200 Syrian doctors who have resettled in the US since the conflict began.
"Nowhere could be substituted for my home country, but the Assad regime forced me to leave Syria or I would have simply become an addition to the number of detainees or torture victims, while the world is enjoying watching our disaster," he said. "Personally, I'm eager to get back to Syria, but I'm sure I would be detained on the borders."
The shortage of doctors in Syria is taking an immense toll.
While the United Nations stopped counting the dead in January, Sahloul estimates there was a "secondary death toll" that was even higher than the number of those killed by firearms and other weapons.
There's a huge secondary death toll. It's not as sexy as 'war trauma', but it's the reality.
He estimates up to 300,000 excessive deaths because of a lack of access to routine medication for chronic diseases such as diabetes and lung disease, along with premature deaths from infectious diseases, malnutrition and neonatal problems.
Sparrow echoed his concerns: "There's a huge secondary death toll. It's not as sexy as 'war trauma', but it's the reality."
The destruction of medical facilities has also left 70,000 cancer patients and 5,000 dialysis patients without necessary treatment.
Othman Shilby, associate director of the Center for Dental Studies at the University of Buffalo in the US state of New York, helped to set up dental clinics on the Turkey-Syria border. He said the dental system in Syria had also been massively affected.
"There is huge demand for dental care in and out of Syria. As soon as refugees started opening their mouths and pointing with their fingers to where the pain was, I saw horrible things," he said. "They have malnutrition and haven't been brushing their teeth or flossing. As a result, they have developed severe cavities and abscesses. We are trying to address these challenges as best as we can, but the demand is too high."
But as the war continues unabated, health experts warn that the destruction of a medical system that was once the envy of the Arab world could take generations to restore.
Follow Sophie Cousins on Twitter: @SophCousins