Accidental 400 mg Modafinil Ingestion Management
Since 400 mg is the maximum FDA-approved daily dose and you have not exceeded toxic levels, you can safely monitor yourself at home for common side effects without requiring emergency medical intervention. 1
Immediate Assessment
You are within the therapeutic range—400 mg represents the upper limit of the approved daily dosing for modafinil, not an overdose 1. The medication has a 15-hour half-life, meaning effects will persist throughout the day and into the evening 1, 2.
Expected Effects and Monitoring
Common symptoms to anticipate over the next 15-24 hours include:
- Central nervous system effects: Insomnia (most likely), headache, nervousness, anxiety, agitation, and dizziness 1, 2
- Cardiovascular effects: Tachycardia (rapid heart rate) is the most common cardiovascular manifestation 3
- Gastrointestinal effects: Nausea, dyspepsia, and back pain 1
These effects are typically mild at the 400 mg dose level 3.
Home Management Strategy
Sleep disruption management:
- Expect significant insomnia tonight since you've taken double your usual morning dose 1
- Do not take any additional modafinil tomorrow morning—skip your next scheduled dose entirely
- Resume your normal 200 mg dose the following day (48 hours after the accidental double dose)
Symptomatic relief:
- If you develop significant anxiety, agitation, or insomnia, benzodiazepines are the first-line treatment 4
- Stay well-hydrated throughout the day
- Avoid caffeine and other stimulants for the next 24 hours
When to Seek Medical Attention
Go to the emergency department immediately if you develop:
- Serious allergic reactions: Rash, hives, mouth sores, blistering skin, facial swelling, or difficulty swallowing/breathing 5
- Cardiovascular symptoms: Chest pain, severe palpitations, or significantly elevated blood pressure 1
- Psychiatric symptoms: Severe agitation unresponsive to reassurance, hallucinations, paranoia, or signs of psychosis 4
- Neurological symptoms: Seizures, severe tremors, or movement disorders 4
Reassuring Context
Overdose case series demonstrate that even ingestions up to 5,000-8,000 mg resulted in moderate symptoms managed with supportive care, with no fatalities reported when appropriate monitoring was provided 4, 3, 6. In a multi-center review of 137 modafinil overdose cases, clinical effects were generally mild with predominantly tachycardia and CNS effects, and only 17% required hospital admission 3.
Key Pitfall to Avoid
Do not attempt to "sleep off" concerning symptoms—while drowsiness is unlikely at this dose, if you develop the serious warning signs listed above (particularly rash, chest pain, or severe psychiatric symptoms), these require immediate medical evaluation rather than waiting 5, 4.