Antidepressants are typically worth considering when depression or anxiety has persisted for at least two weeks, is interfering with your ability to function at work or in relationships, and hasn’t improved with other strategies you’ve tried. There’s no single blood test or score that makes the decision for you, but there are clear patterns that clinicians use to guide the conversation, and understanding them can help you figure out where you stand.
The Two-Week Threshold
Clinical depression isn’t just feeling sad after a bad week. To meet the diagnostic bar, symptoms need to be present most of the day, nearly every day, for at least two consecutive weeks. And at least five of these nine symptoms need to be happening at once: persistent depressed mood, loss of interest or pleasure in things you used to enjoy, significant changes in weight or appetite, sleeping too much or too little, noticeable physical restlessness or slowness, fatigue or low energy, feelings of worthlessness or excessive guilt, difficulty thinking or concentrating, and recurrent thoughts of death or suicide. At least one of those five has to be either depressed mood or loss of interest.
Two weeks might sound short, but the “most of the day, nearly every day” part is key. Everyone has a rough stretch. What separates clinical depression from a rough stretch is how pervasive and unrelenting it feels, and how much it disrupts your normal life.
When Your Daily Life Is Breaking Down
Functional impairment is one of the strongest signals that medication might help. That means depression is getting in the way of your work, your relationships, or your ability to handle basic responsibilities at home. In a large study tracking people with major depression, patients reported missing about 32% of their work time and being impaired nearly half the time they were actually at work. Overall activity impairment, covering everything outside of work, averaged 61%.
Think of it this way: if you’re regularly calling in sick, falling behind on deadlines, withdrawing from friends and family, skipping meals, or unable to keep up with household tasks, those aren’t just “feeling down.” Those are signs that depression has moved beyond your ability to manage it on your own. That level of disruption is exactly what antidepressants are designed to address.
Mild vs. Moderate vs. Severe Depression
Severity matters a lot in this decision. Many clinicians use a brief questionnaire called the PHQ-9 to gauge where you fall. Scores of 5, 10, 15, and 20 mark the lower boundaries of mild, moderate, moderately severe, and severe depression. Scores below 10 rarely show up in people with major depression, while scores of 15 or above usually do.
For mild depression, therapy alone is a reasonable first step, and several major guidelines recommend it. Cognitive behavioral therapy and interpersonal therapy both have strong evidence for mild to moderate cases. Medication and therapy tend to perform similarly in this range, so the choice often comes down to access, preference, and speed. Medication acts faster for most people, while therapy builds skills that protect against relapse over the following six to twelve months.
For moderate depression, the balance tips slightly toward medication or a combination of both. Pharmacotherapy tends to be more effective at reducing acute symptoms quickly and is more cost-effective in settings where therapy access is limited. For severe depression, guidelines are clear: a combination of medication and therapy is the standard approach. In the acute phase of severe depression, therapy alone is often impractical because concentration and motivation are too compromised to engage with it. Medication first, therapy once you’ve stabilized enough to participate.
One important caveat: a widely cited meta-analysis found that antidepressants improved depression scores only about 1.8 points more than a sugar pill in mild to moderate cases. The benefit reached clinical significance only for the most severely depressed patients, those scoring above 28 on a clinical depression scale. And even that gap was driven more by severely depressed patients responding less to placebo than by responding better to the drug. This doesn’t mean antidepressants are useless for moderate depression, but it does mean the benefit is more modest than many people assume, and it strengthens the case for trying therapy first when depression is on the milder end.
It’s Not Just for Depression
Antidepressants are first-line treatment for several anxiety disorders, not just depression. The same class of medications used for depression (SSRIs and SNRIs) are the go-to pharmacological option for generalized anxiety disorder, panic disorder, and social anxiety disorder. If you’re dealing with persistent, disabling anxiety rather than depression, the decision-making process is similar: when it’s interfering with your functioning and non-medication approaches haven’t been enough, it’s reasonable to consider starting one.
Dosing for anxiety typically starts lower than for depression and increases more gradually, partly because people with anxiety disorders can be more sensitive to the initial side effects that sometimes accompany the first week or two on medication.
What to Expect After Starting
Antidepressants don’t work like painkillers. You won’t feel a dramatic shift the day you start. Some patients notice early improvement within the first week, but on average, the onset of noticeable antidepressant effects takes about 13 days. Full response, where you feel meaningfully better across your symptoms, tends to take closer to 20 days. A reliable separation between the medication’s true effect and placebo typically emerges after two to three weeks.
This lag is one of the hardest parts of starting treatment. You may feel side effects before you feel benefits. Knowing the timeline in advance helps: if you don’t feel different after five days, that’s expected, not a sign the medication isn’t working. Most clinicians will reassess after four to six weeks before considering a dose change or switch.
How Long You’ll Likely Stay On
If this is your first depressive episode, plan on at least six months of treatment after you start feeling better. Stopping earlier significantly raises your relapse risk. One study found that the risk of relapse after discontinuation varied by more than 11-fold depending on how long the initial treatment lasted, with the sharpest drop in relapse risk occurring when treatment continued for 16 to 20 weeks or longer.
For people with recurrent episodes, meaning this isn’t the first time, the recommended duration is often longer, sometimes years. The decision to taper off is something to make collaboratively with your prescriber, gradually and with a plan to monitor for returning symptoms.
The Young Adult Warning
If you’re under 25, there’s one additional factor to weigh. Since 2005, all antidepressants in the U.S. carry a black box warning, the FDA’s most serious label, noting a possible link to increased suicidal thoughts and behaviors in children, adolescents, and young adults through age 24. The warning was first issued for those under 18 in 2005 and expanded to include young adults in 2007. It remains in effect today.
This doesn’t mean antidepressants are off the table for younger people. It means the first few weeks after starting or adjusting a dose require closer monitoring. If you’re in this age group and starting medication, expect more frequent check-ins with your prescriber in the early weeks, and take any sudden worsening of mood or new thoughts of self-harm seriously enough to call your provider that day.
Signals That It’s Time to Talk to Someone
You don’t need to arrive at a diagnosis yourself. But if you recognize a cluster of these patterns, it’s worth bringing up medication with a clinician:
- Duration: You’ve felt this way most days for two weeks or longer, not just in waves.
- Functioning: Work, relationships, or basic self-care are visibly slipping.
- Therapy plateau: You’ve tried therapy or lifestyle changes and they haven’t been enough.
- Severity: You’re experiencing several symptoms at once, especially loss of interest, persistent fatigue, concentration problems, or thoughts of death.
- Recurrence: This isn’t the first time. Repeated episodes strengthen the case for medication, both for treatment and prevention.
The decision to start an antidepressant is rarely urgent in the way an antibiotic for an infection is. It’s more like the point where you’ve given other approaches a fair shot, your symptoms are persistent and disruptive, and the potential benefit of medication outweighs the nuisance of side effects and the commitment to staying on it for months. For many people, that tipping point comes later than it should.