Two brand names for two different drugs in the same class. Zoloft is sertraline and Prozac is fluoxetine, both SSRIs — selective serotonin reuptake inhibitors. They work by the same mechanism and differ mainly in how long they stay in the body and in their side-effect profiles.
The core difference
- Zoloft — the brand name for sertraline.
- Prozac — the brand name for fluoxetine.
Different molecules, same class, both prescribed for depression, anxiety and related conditions.
What SSRI means
Selective serotonin reuptake inhibitor. Serotonin released between nerve cells is normally reabsorbed; these drugs slow that reabsorption, leaving more available in the synapse. Selective distinguishes them from earlier antidepressants that affected several neurotransmitters at once and had heavier side effects as a result.
The main practical difference: half-life
Fluoxetine has an unusually long half-life — its active metabolite persists for days. Sertraline clears much faster. The consequences are real:
- Missing a dose of fluoxetine matters less, because levels fall slowly.
- Stopping fluoxetine produces fewer discontinuation effects, since it tapers itself.
- Sertraline reaches a steady state faster, and changes take effect sooner in both directions.
Why Prozac became a household word
Approved in the US in 1987, it was the first SSRI to achieve mass prescription and it arrived with far milder side effects than what preceded it. It entered general culture in a way few medicines have — a bestselling memoir carried its name in the title. Zoloft followed in 1991 and has at times been the more prescribed of the two, without acquiring the same cultural weight.
The others in the class
- Citalopram — Celexa. Escitalopram — Lexapro.
- Paroxetine — Paxil, Seroxat.
- Fluvoxamine — Luvox.
Where the names come from
Both are coined trade names with no meaning, constructed to be pronounceable across languages and legally distinctive. The generic names are the systematic ones: the -oxetine in fluoxetine and the shared structure of the class are what a pharmacist reads.
This page explains the words, not treatment. Anything about medication is a matter for a doctor.
Frequently asked questions
Are Zoloft and Prozac the same drug?
No. Zoloft is sertraline and Prozac is fluoxetine. They are different molecules in the same class, both SSRIs.
What does SSRI mean?
Selective serotonin reuptake inhibitor — a drug that slows the reabsorption of serotonin between nerve cells, leaving more available in the synapse.
What is the main practical difference between them?
Half-life. Fluoxetine stays in the body far longer, so missed doses matter less and stopping produces fewer discontinuation effects. Sertraline clears faster.