It is likely that the dark spots that you are seeing are the normal reaction of your skin to the inflammation and tissue damage done by the pimples in the first place. Many people, especially those with darker skin to begin with, will have darker spots in the areas surrounding where acne
had been previously--after the acne resolves. This is called post inflammatory hyperpigmentation, or PIH. If this is indeed what you have, the good news is that it should go away by itself in the next few months to 2 years. Laser therapy, bleaching agents, or peels can all play a valuable role in the short term management of these spots until they go away by themselves.
There are many details missing from your question that would be important to know before we just assume that it is PIH, however. For example, if this is a recent development, then the treatment would be different from if the scars had been on your face for years. Also, what medications have you tried? There are gels and over the counter creams that can be applied to help lighten some scars if they have been there for some time. If the dark spots have been there for months or years, then there are other options that could be employed, as mentioned above, but would require a visit to a dermatologist
. In the short term, make sure to use sunscreen generously, as some scars actually get worse with sun exposure. In short, best to visit a dermatologist or at least your family doctor
to make sure that you are treating the right condition, and treating it appropriately.