Down the side of the shop is a long list of ailments, including asthma, allergy, dysentery, jaundice, gastric ulcer, polio, paralysis, "All Types of Fever, Skin, Rheumatic, Nervous and Chronic Diseases", which Dr Khanna claims to be expert at treating.
"Dr" Khanna is a quack; his degree has been declared fraudulent by India's Supreme Court. But as with thousands of other fake doctors in Delhi, and tens of thousands across the country, he continues to practise with impunity.
Quackery has flourished in the subcontinent for centuries; now it proliferates like a malignant disease in the squalid "jhuggi clusters", or shanty towns, where one-third of the capital's population is forced to live. The Delhi Medical Association (DMA) believes there may be 30,000 quacks at work in the city - mis-setting bones, making wrong diagnoses, mixing allopathic and ayurvedic medicines into disastrous cocktails.
Their mistakes are sometimes spectacular: one practitioner opened up the abdomen of a man complaining of acute stomach ache and then, explaining that he was infested by a snake, removed his intestine. Shortly afterwards, of course, the man died.
Another fake doctor in the village of Chonchi, outside Delhi, used the same hypodermic to inject all the villagers, who all now have Aids.
Fed up with official apathy toward the problem, 1,000 of Delhi's legitimate doctors and 2,000 supporters marched to demand action last week.
On Monday, three prominent doctors will begin a public hunger strike to put pressure on the city government.
They are angry because last year a Quackery Prohibition Bill received its first reading before the Delhi Legislative Assembly. But it was then referred to a sub-committee, which has been sitting on it ever since. If the sub-committee does not recommend action by today, the process will have to begin all over again.
Dr Rajesh Chawla, president of the DMA and one of the three doctors preparing to begin fasting, said during a sit-down demonstration on Friday that the Bill had been shelved because many quacks are "politically active"; strongly positioned and influential in slum communities, they threaten sitting members of the Legislative Assembly with massive voter defections in the next election if the Bill should be passed.
Dr Chawla says the DMA's figure of 30,000 quacks in Delhi is a guess, based on the experience of the association's 10,000 members.
"Additionally," he said, "6,000 chemists are prescribing medicines. And in the slums, quacks are numerous. In the jhuggi cluster back there" - he gestured in the direction of the fearful riverside slum of Yamuna Pushta, cheek by jowl with Raj Ghat, the spot where Mahatma Gandhi was cremated - "there are 170 unqualified doctors and only one qualified doctor.
"Doctors are being held responsible for the quacks' misdeeds," Dr Chawla went on. "Lots of qualified doctors are looking for jobs, but they can't compete with the quacks, who appear to be cheaper and offer amazing cures.
"The reason multi-drug resistant tuberculosis is rising daily in India is due to overprescription by quacks. Many patients only come to us to die when the quacks have finished with them," Dr Chawla said.Reuse content