S. R. Faruqi:

In this verse, in addition to the superior description of the helplessness of the lover in passion, and the incurableness of the illness of passion, there are two more points. The first is that in passion, some medicines do work, even if their effect would be temporary and later they would do harm. As Hafiz has said [in Persian], 'It's an individual experience that some medicines do good in the very beginning and harm later on'.

The second point is that it's not clear what those medicines even were. In this way he's provided an excellent opportunity for guesswork. For example, it's possible that staying very far away from the beloved might at first have been beneficial-- that is, the speaker might have had, more or less, patience/endurance. But remaining so for a certain amount of time might have further increased his restlessness. Or, from going again and again to the beloved's house he might at first have found peace-- and later, because of repeated beholding, there might have been an increase in his wildness and madness. Or, the beloved's harshness and bitterness of speech might at first have crushed his courage, and might later have further inflamed the blaze of ardor, etc.

There's also a subtle kind of jesting style in the verse. He's composed a very fine verse; the feeling of realism too is peerless. Compare

{7,1}.

Rasikh Azimabadi, taking one aspect of this theme, has composed an enjoyable verse:

dukh sahe tark jo na:z:zaarah-e dil-daar kiyaa
aah parhez ne duunaa hame;N biimaar kiyaa

[when, having endured sorrow, we renounced the sight of the heart-possessor
ah! the abstinence made us twice as sick]

[See also {277,1}; {1494,3}.]

FWP:

SETS == FILL-IN; HI
MOTIFS
NAMES
TERMS

The verse reports something that's not exactly a paradox, but is nevertheless an odd and striking reversal: 'in passion' medicines don't work the way they should. The ones that originally (seem to) work, later become a real source of damage. For it was either 'only' or 'emphatically' those very medicines-- the effective ones-- that later did the speaker harm; and there's no indication in the verse that anything else did the speaker any harm at all. The clever little hii thus sets up the odd situation: one normally takes medicines for an illness, but in the case of passion, after a time the original illness seems to become irrelevant, and only those very medicines themselves do the harm. In a sense 'those medicines' seem to become a new illness.

Thus, as SRF observes, we're invited (and also obliged) to decide for ourselves what medicines are referred to. And of course the most plausible ideas involve either nearness to, or distance from, the beloved. For isn't that what the disease of passion is all about in the first place? The comparison to {7,1} is very apt; in it the situation is made even more explicit.

Note for grammar fans: Tahira Naqvi advocates (Nov. 2021) reading the so as suu (see the definitions above), so that avval suu comes to mean 'toward the beginning'. To me that sounds possible, but not obligatory.