Drug therapy for unipolar depression

Types of antidepressant (NHS)

How they are used

• Usually offered for moderate or severe depression, often with talking therapy.
• They usually start to have an effect in 1 to 2 weeks and can take up to 8 weeks to work fully; symptoms should start to improve within 4 weeks.
• If they work, the same dose is continued for at least 4 to 6 months after symptoms ease.
• They are not addictive, but stopping suddenly can cause withdrawal symptoms, so doses are reduced gradually.
• Fluoxetine is the only SSRI that can be prescribed to under-18s, and only with a specialist's approval.

Evaluation

• Effective for many: most people with moderate or severe depression benefit, though not everyone, and people may need to try two or more.
• Side effects: nausea, headaches, dry mouth, tiredness, sleep and sexual problems (NHS); some improve over time.
• Safety: thoughts of self-harm can occasionally increase when starting, especially in people aged 24 or under, so people are reviewed every 1 to 2 weeks at first.
• Easy and cheap compared with therapy, but they treat symptoms rather than causes such as negative thinking or life problems.
• Relapse: Hollon et al. (2005) found 31% of patients relapsed after cognitive therapy ended, compared with 76% of those withdrawn from medication, so cognitive therapy had a more lasting effect.
• Assumption: rests on the monoamine hypothesis, which is itself challenged.

Worked example

Give one strength and one weakness of SSRIs for a 30-year-old with moderate depression who works long hours.

1. Strength: SSRIs are a tablet taken daily, so they fit around long working hours without weekly appointments, and most people with moderate depression benefit.
2. Weakness: they can take weeks to work and cause side effects such as tiredness and nausea, which could affect work and lead to stopping early.
3. Link: a combination with CBT usually works better than either alone (NHS).

Answer: Apply each point to the person's situation.

Check yourself

1. Which type of antidepressant is usually prescribed first?
   • Tricyclics
   • SSRIs
   • Antipsychotics
   • Benzodiazepines
   Show answer

   SSRIs. SSRIs have fewer side effects than older drugs.

2. Which SSRI is the only one that can be prescribed to under-18s (with specialist approval)?
   • Sertraline
   • Citalopram
   • Paroxetine
   • Fluoxetine
   Show answer

   Fluoxetine. NHS: fluoxetine only.

3. If antidepressants work, for at least how many months should the same dose continue after symptoms ease?
   Show answer

   4 months. At least 4 to 6 months, so the minimum is 4.

4. Why are people starting antidepressants reviewed every 1 to 2 weeks?
   • The drugs are addictive
   • The drugs cure depression in a week
   • Thoughts of self-harm can occasionally increase when starting, especially in younger people
   • To check their IQ
   Show answer

   Thoughts of self-harm can occasionally increase when starting, especially in younger people. Early monitoring is a safety measure.

5. How do tricyclic antidepressants differ from SSRIs?
   • They are older and raise serotonin and noradrenaline, with more side effects
   • They only act on dopamine
   • They are newer with no side effects
   • They are a talking therapy
   Show answer

   They are older and raise serotonin and noradrenaline, with more side effects. TCAs are older with broader action.

6. Explain why drug therapy may not provide a long-term solution to depression.
   Show answer

   Antidepressants treat symptoms rather than causes such as negative thinking or life stress, so when people stop taking them their depression may come back.. Symptom relief without addressing causes risks relapse after stopping.

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Sources

• Pearson Edexcel International Advanced Subsidiary/Advanced Level in Psychology specification (issue January 2026)
• Pearson IAL Psychology component guide: WPS04 (Issue 2, November 2024)
• NHS: Depression in adults, treatment
• NHS: Antidepressants, side effects
• DeRubeis et al. (2005), Cognitive therapy vs medications in the treatment of moderate to severe depression, Archives of General Psychiatry 62
• Vanderbilt University news (2005) on Hollon et al. (2005), Prevention of relapse following cognitive therapy vs medications, Archives of General Psychiatry 62

Last updated 8 November 2026. Spotted a mistake? Tell us.