Does Modafinil Cause Anger or Irritability? Exploring Its Emotional Side Effects

Modafinil improves wakefulness and focus. People also ask if it can change emotions, especially anger or irritability. Most studies do not show a direct link to anger, but some users report irritability or anxiety, and rare psychiatric reactions are documented on the official label (Randall et al., 2003; U.S. Food and Drug Administration, 2015).

What modafinil is and how it is used

Modafinil is a wakefulness-promoting medicine approved for narcolepsy, obstructive sleep apnea, and shift work sleep disorder. It treats excessive sleepiness. It is not approved as a cognitive enhancer or for mood disorders (U.S. Food and Drug Administration, 2015; Greenblatt & Adams, 2023).

Researchers think modafinil increases dopamine and norepinephrine modestly and also affects glutamate and gamma-aminobutyric acid (GABA). These actions involve brain regions linked to attention, emotion, and arousal, including the prefrontal cortex and amygdala (Greenblatt & Adams, 2023; Rasetti et al., 2010).

Can modafinil cause anger or irritability?

Evidence from controlled studies

• Healthy volunteers, 100 mg vs 200 mg: A double-blind trial in young adults found higher ratings of somatic anxiety, restlessness, muscular tension, and irritability at 100 mg compared with placebo and 200 mg. After cognitive testing stress, the 100 mg group also showed higher psychological anxiety and aggressive mood factors (Randall et al., 2003).
• Healthy volunteers, short course: Functional magnetic resonance imaging (fMRI) with 100 mg daily for 7 days showed reduced amygdala reactivity to fearful faces and more efficient prefrontal activity, with trends toward lower anger and anxiety ratings on modafinil compared with placebo (Rasetti et al., 2010).
• First-episode psychosis, 200 mg single dose: Participants improved at recognizing sad facial expressions, with no change in subjective mood ratings during testing. This suggests enhanced emotional processing without a mood shift (Scoriels et al., 2011).
• Schizophrenia-spectrum review: A review reported cognitive benefits and improved aspects of emotional processing, with no consistent emotional worsening across trials (Scoriels et al., 2013).

What the label and clinical references add

The United States Food and Drug Administration (FDA) label lists possible psychiatric symptoms, including anxiety, agitation, aggression, mania, delusions, and hallucinations. These events are uncommon, but the label advises caution in people with a history of psychosis, depression, or mania. It recommends stopping the medicine if psychiatric symptoms appear (U.S. Food and Drug Administration, 2015). Clinical summaries provide similar cautions (Greenblatt & Adams, 2023).

Bottom line: Most users do not become angry. Some may feel irritable or anxious. Risk appears to depend on dose, personal history, and context.

Why dose and personal factors matter

• Dose pattern in trials: Irritability and anxiety signals were higher at 100 mg than at 200 mg or placebo in a controlled study of healthy adults. At 200 mg, mood ratings were generally neutral in that study (Randall et al., 2003).
• Approved dosing:
  • Narcolepsy or obstructive sleep apnea, 200 mg once each morning.
  • Shift work sleep disorder, 200 mg about 1 hour before the shift (U.S. Food and Drug Administration, 2015).
• Personal risk factors: A history of anxiety, bipolar disorder, or psychosis, sleep loss, and use of other stimulating substances may raise the chance of irritability or mood symptoms (U.S. Food and Drug Administration, 2015; Greenblatt & Adams, 2023).
• Sleep timing: Taking modafinil late can disrupt sleep. Poor sleep can worsen mood. Take it at the time recommended for your condition (U.S. Food and Drug Administration, 2015).

How modafinil may change emotional processing

Imaging shows reduced amygdala response to threat and more efficient prefrontal function during cognitive tasks. Some people describe feeling calmer or less reactive. Others may notice emotional blunting. Study data support changes in emotional processing without a consistent positive or negative shift in mood ratings (Rasetti et al., 2010; Scoriels et al., 2011; Scoriels et al., 2013).

What we know about long-term effects on emotion

Most emotion studies used single doses or short courses. Reviews highlight cognitive benefits and improved affect recognition in some clinical groups. Long-term emotional outcomes in general users remain limited and need more research (Scoriels et al., 2013).

Practical guidance for patients

• Use modafinil only under medical supervision for an approved condition.
• Follow the labeled timing to protect sleep.
• Track mood and anxiety for the first 1 to 2 weeks. Keep notes on dose, timing, sleep, caffeine, and other medicines.
• Avoid adding other stimulants unless your clinician recommends it.
• Stop the medicine and contact your clinician if you notice new or worsening anxiety, agitation, irritability, anger, unusual thoughts, or behavior changes (U.S. Food and Drug Administration, 2015; Greenblatt & Adams, 2023).

When to seek urgent care

Seek urgent medical help for any of the following after starting modafinil:

• Severe anxiety, agitation, aggression, or panic.
• Hallucinations, delusions, mania, or suicidal thoughts.
• Rash, hives, swelling of the face or tongue, trouble breathing.
  These signs can indicate rare but serious reactions described in the label (U.S. Food and Drug Administration, 2015).

FAQs

Can modafinil make me angry?

Anger is uncommon in trials. Some users feel irritable or anxious, especially at 100 mg. At 200 mg, mood effects were often neutral in a controlled study, but individual responses vary (Randall et al., 2003).

Why would 100 mg feel worse than 200 mg?

A controlled study reported more somatic anxiety and irritability at 100 mg than at 200 mg or placebo. Differences in arousal, sensitivity, and study conditions may explain this finding (Randall et al., 2003).

Can I take modafinil at night?

Not for daytime sleepiness disorders. It can interfere with sleep if taken late. For shift work sleep disorder, take 200 mg about 1 hour before the shift as directed on the label (U.S. Food and Drug Administration, 2015).

Does modafinil treat anxiety or depression?

No. It is not approved for anxiety or depression. Some people feel calmer, and imaging shows dampened amygdala response to fear, but others may feel keyed up. Discuss risks and monitoring with your clinician if you have a mood or anxiety disorder (Rasetti et al., 2010; U.S. Food and Drug Administration, 2015).

This article is for general information and does not replace medical advice. Talk with a qualified clinician about your situation.

References

• U.S. Food and Drug Administration. (2015). PROVIGIL® (modafinil) tablets, for oral use, C-IV [Prescribing information]. U.S. Department of Health and Human Services. https://www.accessdata.fda.gov/drugsatfda_docs/label/2015/020717s037s038lbl.pdf
• Greenblatt, K., & Adams, N. (2023, February 6). Modafinil. In StatPearls [Internet]. StatPearls Publishing. https://www.ncbi.nlm.nih.gov/books/NBK531476/
• Rasetti, R., Mattay, V. S., Stankevich, B., Skjei, K., Blasi, G., Sambataro, F., Arrillaga-Romany, I. C., Goldberg, T. E., Callicott, J. H., Apud, J. A., & Weinberger, D. R. (2010). Modulatory effects of modafinil on neural circuits regulating emotion and cognition. Neuropsychopharmacology, 35(10), 2101–2109. https://doi.org/10.1038/npp.2010.83
• Randall, D. C., Shneerson, J. M., Plaha, K. K., & File, S. E. (2003). Modafinil affects mood, but not cognitive function, in healthy young volunteers. Human Psychopharmacology: Clinical and Experimental, 18(3), 163–173. https://doi.org/10.1002/hup.456
• Scoriels, L., Jones, P. B., & Sahakian, B. J. (2013). Modafinil effects on cognition and emotion in schizophrenia and its neurochemical modulation in the brain. Neuropharmacology, 64, 168–184. https://doi.org/10.1016/j.neuropharm.2012.07.011
• Scoriels, L., Barnett, J. H., Murray, G. K., Cherukuru, S., Fielding, M., Cheng, F., Lennox, B. R., Sahakian, B. J., & Jones, P. B. (2011). Effects of modafinil on emotional processing in first episode psychosis. Biological Psychiatry, 69(5), 457–464. https://doi.org/10.1016/j.biopsych.2010.09.043