Can You Cut Modafinil in Half? What to Know Before Splitting Tablets

Modafinil is a wakefulness medicine used for narcolepsy, obstructive sleep apnea (OSA), and shift work disorder (SWD). Many people ask if they can cut tablets to lower the dose or save money. The short answer is that splitting can lead to uneven doses and unpredictable effects. Safer options usually exist, such as using 100 mg tablets or a prescribed split-dose schedule that uses whole tablets (U.S. Food and Drug Administration, 2015; Grissinger, 2010).

What does “splitting Modafinil” mean?

Splitting means cutting one tablet into two or more pieces to change the dose. Modafinil is available as 100 mg and 200 mg tablets. The 200 mg tablet has a score line, but the label does not say that splitting gives accurate halves or that splitting is recommended. A score line helps a tablet break, but it does not guarantee equal drug content in each piece (U.S. Food and Drug Administration, 2015; Grissinger, 2010).

Is it safe to split Modafinil tablets?

Safety depends on accurate dosing. Studies of tablet splitting across many medicines show frequent dose errors when tablets are cut, including with scored tablets. Many halves fall outside a 10 percent accuracy range, and some vary by more than 20 percent. That can reduce benefit or raise side effects (Grissinger, 2010; Chaudhri et al., 2019).

The Modafinil label lists approved strengths and dosing, but it does not evaluate or endorse splitting for dose accuracy. Using a lower-strength whole tablet is the safer way to reduce dose when appropriate (U.S. Food and Drug Administration, 2015).

Does Modafinil’s long half-life make splitting unnecessary?

Often yes. Modafinil is absorbed by mouth and has an elimination half-life around 12 to 15 hours. This supports once-daily dosing for most people. Steady state is typically reached after several days of daily use (Wong et al., 1999; Greenblatt & Adams, 2023). If you feel the effect wears off too early, speak with your clinician before changing your dose.

Will splitting affect effectiveness?

Cutting can lead to uneven doses, which may cause variable effects from day to day. That is different from a split-dose regimen. In certain patients with late-day sleepiness, studies show that taking whole tablets in two doses, such as 200 mg in the morning and 200 mg at midday, can improve evening wakefulness compared with a single morning dose. These regimens use intact tablets, not cut tablets (Schwartz et al., 2003; Schwartz et al., 2005). Ask your prescriber if a split-dose plan is suitable for you.

Risks of uneven dosing and side effects

Uneven tablet halves can lead to:

Too high a dose on some days with headache, anxiety, nausea, or insomnia
Too low a dose on other days with reduced wakefulness
Confusion about which pieces were taken and how much remains

These risks add to the medicine’s known adverse effects profile, which includes headache, nausea, anxiety, insomnia, and other reactions noted in the prescribing information (U.S. Food and Drug Administration, 2015; Greenblatt & Adams, 2023; Grissinger, 2010).

Safer alternatives to splitting

Talk with your clinician about:

Using 100 mg tablets when a lower dose is needed.
A split-dose regimen with whole tablets if you have late-afternoon or evening sleepiness, for example 200 mg in the morning and 200 mg at noon when appropriate (Schwartz et al., 2003; Schwartz et al., 2005).
Timing adjustments within approved dosing guidance for your condition (U.S. Food and Drug Administration, 2015).

Who should not split or self-adjust dosing?

Avoid cutting tablets or changing dosing without medical advice if you have:

Heart disease, uncontrolled high blood pressure, or prior stimulant-related heart symptoms
Liver impairment or you are an older adult who may need lower doses
A history of anxiety, mania, psychosis, or severe skin reactions to medicines

These situations need closer monitoring and careful dose selection by a clinician (U.S. Food and Drug Administration, 2015; Greenblatt & Adams, 2023).

If your clinician still approves splitting, use these precautions

If a clinician instructs you to split tablets, improve safety with these steps:

Use a dedicated tablet splitter, not a knife or your hands.
Split only what you will use soon, and store both halves together in the same original container.
Label the container clearly, and keep dosing consistent.
Never mix different strengths in one bottle.
Stop and contact your clinician if you notice new or worsening side effects or if dosing becomes confusing (Grissinger, 2010).

When to contact your clinician

Call your clinician if you have any of the following:

New or worsening headache, anxiety, palpitations, chest pain, rash, or insomnia
Return of excessive sleepiness that affects safety, such as while driving
Any uncertainty about the dose you are actually taking (U.S. Food and Drug Administration, 2015)

FAQs

Can I take Modafinil at night?

For shift work disorder, the recommended dose is one hour before the start of the work shift. Taking Modafinil late in the day for other conditions may cause insomnia. Ask your clinician for timing guidance based on your diagnosis and schedule (U.S. Food and Drug Administration, 2015).

Does the 200 mg dose cost more than the 100 mg dose?

Prices vary by pharmacy and region. In many cases the price per tablet is similar across strengths, which is why some people consider splitting for cost reasons. This practice can create dosing errors. Ask your clinician or pharmacist about safe, cost-effective options like prescribing 100 mg tablets when a lower dose is needed (Grissinger, 2010).

Is cutting along the score line precise?

No. A score line helps break the tablet, but studies show that split pieces can still be inaccurate in weight and drug content, even when scored. This can affect how you feel each day (Grissinger, 2010; Chaudhri et al., 2019).

Is Modafinil extended release?

No. Modafinil is not an extended-release product. It still has a long half-life, which supports once-daily dosing for most people. The label does not recommend splitting for dose accuracy (U.S. Food and Drug Administration, 2015; Greenblatt & Adams, 2023).

References

Chaudhri, K., Kearney, M., Di Tanna, G. L., Day, R. O., Rodgers, A., & Atkins, E. R. (2019). Does splitting a tablet obtain the accurate dose?: A systematic review protocol. Medicine (Baltimore), 98(42), e17189. https://doi.org/10.1097/MD.0000000000017189
Greenblatt, K., & Adams, N. (2023). Modafinil. In StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan–. Retrieved from https://www.ncbi.nlm.nih.gov/books/NBK531476/
Grissinger, M. (2010, February). Tablet splitting—Only if you “half” to. P & T, 35(2), 69–70. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2827917/
Schwartz, J. R. L., Feldman, N. T., & Bogan, R. K. (2005). Dose effects of modafinil in sustaining wakefulness in narcolepsy patients with residual evening sleepiness. Journal of Neuropsychiatry and Clinical Neurosciences, 17(3), 405–412. https://doi.org/10.1176/jnp.17.3.405
Schwartz, J. R. L., Feldman, N. T., Bogan, R. K., Nelson, M. T., & Hughes, R. J. (2003). Dosing regimen effects of modafinil for improving daytime wakefulness in patients with narcolepsy. Clinical Neuropharmacology, 26(5), 252–257. https://doi.org/10.1097/00002826-200309000-00009
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. Retrieved from https://www.accessdata.fda.gov/drugsatfda_docs/label/2015/020717s037s038lbl.pdf
Wong, Y. N., Simcoe, D., Hartman, L. N., Laughton, W. B., King, S. P., McCormick, G. C., & Grebow, P. E. (1999). A double-blind, placebo-controlled, ascending-dose evaluation of the pharmacokinetics and tolerability of modafinil tablets in healthy male volunteers. Journal of Clinical Pharmacology, 39(1), 30–40. https://doi.org/10.1177/00912709922007534