"Medicine, medicine," the street dealers shout. "Any kind you want."
Business is brisk. For many Iranians, such underground channels are now the only way to get needed - or even life-saving - drugs as Western sanctions over the country's nuclear program have indirectly limited normal supplies to hospitals and pharmacies.
But for others, even the sidewalk touts are not an option. Iran's sinking currency has more than doubled the prices of some of the imported medicines and supplies, potentially putting them out of reach for lower-income patients.
While medicine and humanitarian supplies are not blocked by the economic embargoes on Iran, the pressures are clearly evident in nearly every level of Iranian health care. It's a sign of the domino effect of sanctions on everyday life.
Restrictions on Iran's access to international banking networks mean major obstacles to pay for imported medicine and equipment - the same troubles facing many businesses in need of shipments from abroad.
Meanwhile, the nation's slumping currency - seen as collateral damage from sanctions - has driven up prices sharply. An imported wheelchair now costs 10 times more than last fall. A blood-sugar test kit has more than doubled to 540,000 rials, or about $18.
The black market still finds ways to get medical supplies through smuggling routes or by simply carrying shipments by hand, but the prices can be even higher than on regular shelves.
"You pay in advance and I will bring the medicine you need later," said Behzad, a street medicine dealer who would give only his first name. "We have all sorts of medicines: European, Indian or Chinese. It depends on your budget."
The economic blows from sanctions are most acutely felt in key industries such as oil, which accounts for nearly 80 percent of Iran's foreign revenue. On Monday, the head of Iran's parliamentary budget committee, Gholam Reza Kateb, said receipts from oil and gas exports have fallen by 45 percent in the past nine months. The announcement appeared part of political early warnings before expected austerity measures in March that will likely include major tax hikes.
But Iranian authorities also know the challenges of trying to squeeze more money from an economy showing serious signs of strain.
Cheaper Asian parts and products are increasingly taking the place of Western goods. Factories depending on imported raw materials are struggling to stay in operation. Prices for nearly everything - including health services and medicine - continue to climb as the rial stumbles along at about one-third its exchange rate value compared with 18 months ago.
"I'll decide whose turn it is," barked emergency nurse Zahra Rahmati at the state-run hospital in central Tehran, where dozens of patients clamored for attention.
Scenes of overcrowded state hospitals are now common across Iran after fees for private health care have nearly doubled in recent months. The costs in state-run facilities are far cheaper, but that also comes with shortages and long waits.
"Sometimes we don't even have serum for dehydrated patients, said a young doctor, speaking on condition of anonymity because he was worried that comments to the media could jeopardize his job at a state-run hospital.
The prices for other items have soared in recent months: radiology film up 240 percent; helium gas for MRIs up 667 percent; filters for kidney dialysis up 325 percent. The cost of one round of chemotherapy for cancer has reached 200 million rials, or $65,000, from 800 million rials, or $25,000, last year.
The independent Hamshari daily quoted a father - who was not named in the article - as saying his child died because he couldn't afford the higher price of an artificial heart valve.
At a major pharmacy in Tehran, a 53-year-old father slumped over - his head in his hands - as he looked at the prices for medicine for his teenage daughter, who is suffering from stomach cancer.
"How can I afford buying medicine as prices have doubled over a week?" said Hooshang, who gave only his first name.
Hossein Ali Shahriari, head of parliament's health committee, said he has appealed to President Mahmoud Ahmadinejad to address shortages and rising prices in the health sector. Today, prices of some medicines and paramedical equipment have increased by 200 percent, he said.
Shahriari said even powdered milk for infants is not available in some pharmacies.
Iran's health ministry and charity organizations, in separate letters to international bodies, have requested an easing of the banking embargo for health and medicine sectors. But Ahmadinejad also has come under criticism for trimming the budget for health care imports.
Iran's former health minister Marzieh Vahid Dastjerdi - the only female Cabinet member in Iran since the 1979 Islamic Revolution - claimed that the $650 million budgeted is less than a quarter of what's needed to keep state-run hospitals and pharmacies adequately supplied. Her challenge to Ahmadinejad led to her dismissal in late December.
The shortages prompted a warning letter in November to Ahmadinejad by 48 chancellors of medical schools across Iran.
"Lack of purchase power to obtain medical equipment and discontent of patients and hospital staff could lead to student protests, too," said the letter.
At a recovery center in Tehran, 8-year-old Milad Rostami's mother watches over him carefully. The boy suffers from hemophilia and is currently recovering from knee surgery. His mother, Fatemeh, knows there is a long waiting list for a blood product needed to halt bleeding if the boy falls or re-injures his knee.
"There is no hope," said Ahmad Ghavidel, head of Iran's Hemophilia Association, a charity body. "There is no hope for his health."
At dawn in another part of Tehran, patients are leaving the emergency room at the state-run hospital. Some carried pills, but others could get no treatment.
"I don't know how many of them will survive until my next shift," said Rahmati, the nurse. "I did my best, but I know it was not the best for them."
As she walked out of the hospital, more patients were heading in.