However, it must be noted that caffeine has an undefined and most likely negligible effect on the serotonin system. Jitteriness is a side effect that appears during the first week after taking Zoloft (some have noted that taking Zoloft with food helps relieve the problem). Sometimes this feeling of agitation is so strong that some people starting on Zoloft initially lose a few pounds. Subsequent weight loss may also be due to decreased appetite and increased activity, such as knee jiggling and finger-tapping. Another common side effect is teeth grinding.

Although many of the side effects described above are also those of amphetamine, a drug with intense serotonin uptake inhibition, Zoloft do not give a “speedy” type of feeling. For the most part, people using Zoloft feel quite normal. One side effect that may interfere with daily life is insomnia, which occurs in up to 14 percent of people who take Zoloft, but only 2 percent actually have to drop out of treatment because of the effect. Sometimes patients are counseled on taking Zoloft only in the morning, so that their sleep is not disrupted. Or, less commonly, a sleeping aid can be prescribed. Over time the initial feeling of agitation tends to dissipate, and usually after 4–6 weeks the beneficial effects kick in. During this time, a patient must be encouraged to stay on the drug since Zoloft time frame of effect can be different for everyone. However, when improvement in mood does occur, in most cases there is no miraculous personality change.

Sometimes when people with long-term, chronic depression begin to feel better, it may seem as if there has been a complete transformation in character. But the more typical response reported is the feeling that one’s old self is back. Most patients on Zoloft do not feel “better than well” (to use the phrase coined by Brown University psychiatrist Peter Kramer). Zoloft, or any SSRI, simply makes it possible to enjoy life again, changing brain chemistry so that negative thinking is no longer the norm.