Modafinil Side Effects, Interactions, Warning, Dosage and Uses

Modafinil: Side Effects, Interactions, Warning, Dosage and Uses

Modafinil or Provigil, as it is also called, is an orally administered medication that can trigger wakefulness. it is a racemic compound and its chemical moniker is 2-diphenymethyl-sulfinyl-acetamide. The molecular formula is C15H15NO25 and the molecular weight is around 273 approximately.

In appearance, Modafinil is a white or off-white crystalline powder that is insoluble in water and cyclohexanol. It has slight to sparing solubility in methanol and acetone.These tablets contain 100-200mg of Modafinil and the inactive ingredients like lactose monohydrte, magnesium stearate and povidone as well as pre-gelatinized starch. You need to get medical help in case you develop allergies post the ingestion of this medication though. Modafinil works to improve wakefulness in adult clinical cases facing excessive sleepiness. Certain conditions like narcolepsy, obstructive sleep apnea and shift work disorder are associated with this medication.

However it should be remembered that Modafinil treats the excessive sleepiness only. If obstruction is resulting, a more holistic and comprehensive treatment for it has to be followed.

Dosage of Modafinil

In narcoloepsy and obstructive sleep apnea, dosage needs to be taken in terms of 200 mg taken in an oral form once a day as a single dosage in the morning. Doses up to 400 mg in a single day are a good option for adult dosages. These have been proven to be tolerated well. But there is currently no research supporting the benefits of going beyond 200 mg per day.

In case of shift work disorder, the recommended dose of Modafinil for clinical cases is 200mg taken once in a day as a single dosage around 1 hour before the start of the work shift.


In those with severe hepatic problems, Modafinil should be taken as a half of what normal patients are given. Lower doses and close monitoring is also there in special cases like the elderly and senior patients.

Contraindications/Side Effects

These drugs are contraindicated in those with hypersensitivity or allergy to its inactive ingredients apart from the medication itself. Here are the contraindications for those taking this medicine.


Contraindications/Side Effects
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Serious rash needs medical care and medical treatment needs to be discontinued with the use of Modafinil. In clinical trials the chances of rash occurring are 13 in about 1585 cases in younger patients. The rashes also show a rare chance of developing into a Stevens Johnson syndrome, according to one research. Other cases of rare hypersensitivity affecting organs was also noted. Many cases are associated with fever and pathologies like vomiting.

There have been rare possibilities of life threatening rash as well such as TEN/Toxic Epidermal Necrolysis and Drug Rash with Eosinophilia and Systemic Symptoms. The worldwide incidence of such reactions is thought to be underreported and prevalent in at least 1-2 cases per million. The chance of occurrence of rash associated with Modafinil is most likely to occur anywhere around 5 weeks post the treatment. Some cases can even occur post months.

Benign rashes also occur with this form of medication. Modafinil should not be continued once rashes appear. Only when the rash or hives are unrelated should the drug continue to be used.

Angioedema plus Anaphylaxis

Angioederma and allergies are also observed in patients treated with arModafinil. However, angioedema has been singly noted in the case of those ingesting Modafinil. Patients need to discontinue therapy and report problems to their doctors when there is water retention or swelling of body parts like lips and eyes known as anaphylaxis. Difficulty in swallowing and breathing also need to be countered.

Multi Organ Reactions

These hypersensitive reactions occur post the ingestion of the medication within 13 days in one fatal case. Limited reports aside, the multi organ hypersensitivity can result in hospitalization. Hepatitis or liver problems, myocarditis or heart abnormalities and hematological issues as well as asthenia are noted in those having an adverse indication to Modafinil. This drug should be discontinued if this problem is suspected.

Abnormal Sleep/Sleep Pathologies

Patients with abnormal levels of sleepiness should be discontinuing this medication if their level of alertness does not come back to normal. Modafinil taking patients who are using it to counter sleepiness must be advised to not undertake dangerous activity like driving.

Psychiatric Problems

Psychiatric issues are also noted in some cases of Modafinil. Research has found that patients treated with this medication report some amount of anxiety, insomnia, confusion, depression and agitation but the percentage is very small. Mania, psychosis, aggression and suicidal thoughts are common in those who report psychiatric symptoms.

Generally, patients taking this medicine should be treated carefully and once the drug is taken, an alert should be issued for any mental illness/mental health issues.

Functional Impairment

Modafinil has been shown to affect the central nervous system and alter judgment as well as motor skills and thinking. Driving or operating machinery under such circumstances may not be advisable.

Heart Problems

Adverse health issues for the heart may occur including dyspnea, transient is-chemic T-wave changes, chest pains, palpitations and more. Mitral valve prolapsing or ventricular hypertrophy in the left side has also been noted in some cases. Arrhythmia like tachycardia and bradycardia have also been noted. Patients with heart health issues should stop the medication immediately.

Blood Pressure

While BP monitoring has found no changes in blood pressure post the medication, retrospective analysis of the use of these drugs have shown increased reliance on anti hypertensive medication in those using Modafinil.

Side Effects of Modafinil

The following side effects can occur- heart issues, angioedema, anaphylaxis, multiple organ issues, serious rash, mild functional impairments, psychiatric symptoms and so on. Apart from these, the following may be noted:

  • Diarrhea
  • Dizziness
  • Rhinitis
  • Anxiety
  • Nausea
  • Headache
  • Back Pain
  • Insomnia
  • Dyspepsia
  • Heart or liver problems
  • Somnolence
  • Abnormal vision
  • Confusion
  • Asthma
  • Chills
  • Vasodilation
  • Edema
  • Emotional Lability
  • Mouth ulcers and digestive problems
  • Hyperkinesia
  • Epitaxsis
  • Tremors
  • Adverse reactions are also dependent on the dose in some cases like headache and anxiety. Apart from this hematologic and psychiatric/psychomotor problems can also happen.


CYP3A4/5 Substrates

Clearance of drugs that are these types for Modafinil users can result in lower systemic exposure. This includes steroids, contraceptives or birth control pills, triazolam, midazolam and cyclosporine. Steroids, for example, may not work when used with Provigil. Modafinil can also lower the other drugs.


This includes diazepam, clomipramine, omeprazole, propanolol, phenytoin and can be prolonged by the use of provigil. Inhibition of metabolic enzymes in Modafinil patients can result in greater sensitivity to these drugs. This includes drugs like SSRIs and tricyclic antidepressants too.


This drug’s impact in terms of monitoring prothrombin times/INR should be taken into account when both warfarin and modafinil are jointly taken. Additionally, monoamine oxidase inhibitors should be taken with care by Modafinil users.


Serious rash associated with modafinil means the drug should be stopped immediately. Also, young patients/pediatric cases should not be treated for sleepiness or any other indication using this drug.

Modafinil should only be taken in those who have complete evaluation of their problem and the diagnosis of OSA, SWD or narcolepsy/excessive sleepiness has been diagnosed keeping ICD-10 or DSM-4r classifications in mind. This evaluation comprises complete history and even an examination of mental and physical faculties. For patients suffering from two or more of these diseases, the medication needs to be regulated with care.

It can also impact the central nervous system and signs for abuse or dependence should be watched out for, as modafinil can impair judgment. Additionally, in senior patients, the use of modafinil needs to be carefully regulated.

Studies have also focused on mutagenesis and impairment of fertility or cancer causation as a result of Modafinil. Fetal abnormalities can result in pregnancy due to ingestion of Modafinil. It is not recommended for pregnant or lactating mothers as a result.


Modafinil  uses
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Modafinil is used for promoting alertness and wakefulness. It has waking up properties similar to sympathomimetic agents such as amphetamines or even methyl-phenidate. The induced wakefulness apart, this medication is not a dopamine receptor agonist. It does inhibit this neurotransmitter though. Modafinil is a 1:1 racemic substance where different pharmo kinetic movements can result when R-Modafinil is taken as opposed to S-modafinil in adult patients. Total exposure to R-modafinil is three times more potent than the S version for example. It is taken orally with peak concentration in plasma occurring within a couple of hours. Aqueous suspension determines the bio-availability of these tablets.

Time taken to reach peak concentration varies depending on the food ingested alongside. Modafinil lowers sleepiness caused due to sleep disorders in all forms. If you have a work schedule or pressing engagement, it can help you to stay awake! It also puts you on a normal state for those with shift work disorders. It is not used to hold off sleep in those without the disorder though.This drug can be taken with or without food depending on the prescription and accordingly monitored and regulated as per side effects, interactions and the patient’s medical history is thoroughly examined before prescribing this medication. If you like to learn more on Modafinil , please visit

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