What can be expected on the second night of taking 7.5mg of mirtazapine (Remeron)?

What to Expect on the Second Night of Mirtazapine 7.5mg

On the second night of mirtazapine 7.5mg, you can expect improved sleep quality with reduced sleep latency and increased total sleep time, along with sedation that is typically more pronounced at this lower dose. 1, 2

Sleep Improvements Expected

• Sleep onset will likely improve within the first week, as mirtazapine demonstrates early effects on sleep disturbances and anxiety symptoms, often before the full antidepressant effect emerges at 2-4 weeks 1

• Increased total sleep time and sleep quality are characteristic effects due to mirtazapine's potent histamine H1 receptor antagonism, which is responsible for its sedating properties 2

• The sedative effect is paradoxically stronger at lower doses (7.5-15mg) compared to higher therapeutic doses (30-45mg), because at lower doses the antihistaminic effects predominate without the counterbalancing noradrenergic activation seen at higher doses 1, 3

Common Side Effects on Night Two

• Sedation and drowsiness are the most common effects, with sedation being dose-dependent and more prominent at subtherapeutic doses like 7.5mg 3, 4

• Morning grogginess or "hangover effect" may occur due to mirtazapine's elimination half-life of 20-40 hours, meaning the drug accumulates and steady-state concentrations are not reached until after 4 days of dosing 1, 4

• Increased appetite may begin to emerge, though this typically becomes more noticeable after several days of treatment 1, 5

• Dry mouth can occur but is less pronounced than with tricyclic antidepressants 4

Critical Clinical Considerations

• The 7.5mg dose is below the recommended starting dose of 15mg for antidepressant effects, but is commonly used off-label specifically for sleep due to enhanced sedation at lower doses 1, 3

• Avoid combining with alcohol or other CNS depressants, as mirtazapine potentiates cognitive and motor impairment when used concomitantly 2

• No cardiovascular, anticholinergic, or sexual side effects are expected at this dose, which distinguishes mirtazapine from tricyclic antidepressants and SSRIs 1, 4

Rare but Serious Monitoring

• While agranulocytosis is extremely rare (approximately 1 in 1,000), it is reversible when the medication is stopped and typically occurs after longer-term use, not after two nights 5

• Mirtazapine is safe in overdose, with cases up to 975mg causing only significant sedation without cardiovascular, respiratory effects, or seizures 1

Timing and Accumulation

• Peak plasma concentrations occur 2.2 to 3.1 hours after dosing, so the maximal sedative effect will be felt in the middle of the night if taken at bedtime 2

• Steady-state is not yet achieved on night two, so effects may continue to build over the next 2-3 days as the drug accumulates 4