Antidepressants Explained: SSRIs, SNRIs & More
Plain-language guide to antidepressant medications: how they work, different types, what to expect, and how to work with your doctor.
Clinically Reviewed: Board-Certified Psychiatrist |Next Review: January 2026
Key Takeaways
- Multiple types of antidepressants work in different ways; treatment is tailored to your symptoms
- Most antidepressants take 4-8 weeks to show full benefits
- Side effects often improve after the first 1-2 weeks
- Never stop antidepressants abruptly—work with your doctor to taper safely
- Finding the right medication may require trial and adjustment with your psychiatrist
How Antidepressants Help
Antidepressants work by adjusting the levels of neurotransmitters (chemical messengers) in your brain. These chemicals—particularly serotonin, norepinephrine, and dopamine—play crucial roles in mood, energy, sleep, and emotional regulation.
In depression, these neurotransmitter systems often aren't functioning optimally. Antidepressants help restore better balance, which can improve your mood, energy, motivation, and overall quality of life.
Types of Antidepressants
SSRIs (Selective Serotonin Reuptake Inhibitors)
Most commonly prescribed antidepressants. They increase serotonin levels in the brain.
Common SSRIs:
- Sertraline (Zoloft)
- Escitalopram (Lexapro)
- Fluoxetine (Prozac)
- Paroxetine (Paxil)
- Citalopram (Celexa)
Common side effects: Nausea, sexual effects, sleep changes, initial activation
Best for: First-line treatment for depression and anxiety
SNRIs (Serotonin-Norepinephrine Reuptake Inhibitors)
Increase both serotonin and norepinephrine. May be more effective for some people.
Common SNRIs:
- Venlafaxine (Effexor)
- Duloxetine (Cymbalta)
- Desvenlafaxine (Pristiq)
Common side effects: Similar to SSRIs; may increase blood pressure at higher doses
Best for: Depression with low energy, chronic pain, when SSRIs haven't worked
Bupropion (Wellbutrin)
Affects dopamine and norepinephrine. Structurally different from SSRIs/SNRIs.
Common side effects: Activation, restlessness, dry mouth; NO sexual side effects
Best for: Low energy depression, when avoiding sexual side effects, smoking cessation
Caution: Can lower seizure threshold at high doses
Mirtazapine (Remeron)
Works on multiple receptors; particularly helpful for sleep and appetite.
Common side effects: Sedation, increased appetite, weight gain
Best for: Depression with insomnia, poor appetite, when SSRIs didn't work
Timeline to Benefit
- Week 1-2: Possible improvement in sleep or energy; side effects may be more noticeable than benefits
- Week 2-4: Some people notice mood starting to lift
- Week 4-6: More consistent mood improvement for most responders
- Week 6-8: Full therapeutic effect typically reached; time to assess response
Frequently Asked Questions
How long until antidepressants work?
Most people start noticing some changes in sleep or energy within 1-2 weeks, but full mood benefits typically take 4-8 weeks. It's important to give medications adequate time to work before deciding they're not effective.
Do I have to take them forever?
Not necessarily. Most guidelines recommend staying on antidepressants for at least 6-12 months after symptoms improve to prevent relapse. Some people need longer-term treatment, while others can taper off successfully. This decision should be made with your doctor based on your history.
What if the first medication doesn't work?
This is common—about 40-50% of people don't respond adequately to their first antidepressant. Your psychiatrist can try a different medication, adjust the dose, add a second medication, or explore other treatment options like TMS or therapy.
Can I drink alcohol on antidepressants?
Moderate alcohol use is generally safe with most antidepressants, but alcohol can worsen depression, interfere with medication effectiveness, and increase side effects like sedation. Discuss your alcohol use honestly with your doctor.
Will I gain weight on antidepressants?
It depends on the medication. Some (mirtazapine, paroxetine) are more likely to cause weight gain, while others (bupropion, fluoxetine) are weight-neutral or may cause weight loss. If weight is a concern, discuss medication options with your psychiatrist.
What about sexual side effects?
SSRIs and SNRIs commonly cause sexual side effects (decreased libido, difficulty achieving orgasm). This affects 30-60% of users. Bupropion, mirtazapine, or adding medications like bupropion can help. Be honest with your doctor—solutions are available.
Can I stop taking antidepressants if I feel better?
Don't stop without consulting your doctor. Abrupt discontinuation can cause withdrawal symptoms (dizziness, flu-like symptoms, mood changes). Most guidelines recommend continuing for 6-12 months after improvement, then tapering gradually if you and your doctor decide to stop.
Are antidepressants addictive?
No, antidepressants are not addictive in the way opioids or benzodiazepines are. You don't develop tolerance or cravings. However, your body does adjust to them, which is why stopping abruptly can cause withdrawal symptoms. That's different from addiction.
What's the difference between SSRIs and SNRIs?
SSRIs (Selective Serotonin Reuptake Inhibitors) primarily increase serotonin. SNRIs (Serotonin-Norepinephrine Reuptake Inhibitors) increase both serotonin and norepinephrine. SNRIs may be more effective for some people, particularly if you have low energy or pain alongside depression.
Can I take antidepressants while pregnant?
This requires careful discussion with your doctor. Some antidepressants are safer than others during pregnancy. Untreated depression also carries risks for both mother and baby. Your psychiatrist will help you weigh the risks and benefits to make an informed decision.
Do antidepressants change your personality?
No, antidepressants don't change your core personality. They help restore your brain chemistry to healthier levels so you can feel more like yourself. If you feel emotionally numb or unlike yourself on medication, tell your doctor—dose adjustment or medication change may help.
What if I forget a dose?
If you miss one dose, take it as soon as you remember unless it's almost time for the next dose. Don't double up. Missing occasional doses usually isn't harmful, but consistency is important for maintaining steady blood levels and avoiding withdrawal symptoms.
References
- 1. APA Practice Guidelines for Treatment of Major Depressive Disorder, 3rd Edition (2010)
- 2. Cipriani A, et al. (2018). "Comparative efficacy and acceptability of 21 antidepressant drugs." Lancet 391:1357-1366.