Modafinil Side Effects: A Complete 2021 Guide

Benjamin Martin - 2 April 2021

The ultimate guide to modafinil UK

Modafinil has been touted as a "safe" nootropic, study drug or smart pill (whichever term you prefer), but is that true?

We asked our team of experts to explore the existing literature and to delve a little deeper into modafinil's side effects. We examined people's personal experiences and existing scientific literature to dig to the bottom of this issue.

Does modafinil have any side effects? What are they - and what do most users report as problems? What would we recommend to take instead of modafinil?

Find out the answers to these questions (and more) by reading on.


  • Overview: What is modafinil?
  • Background: What is modafinil used for?
  • What are modafinil's side effects?
  • What are modafinil's long-term side effects?
  • Conclusion & our recommended modafinil alternative

Overview: What is modafinil?

Modafinil - Provigil (generic) - is the most popular ‘study drug’ in Britain.

The Tab has estimated that around 20% of all students in the UK have used it, and it can often seem like a ‘miracle drug’ for students and those who want to concentrate/focus better.

If you want to learn more about modafinil, click here to head to our Ultimate Modafinil Guide.

But, does modafinil have side-effects?

This article will look at modafinil scientifically, referencing studies and published material, to determine whether modafinil has side effects that you should be concerned about if taking it as a ‘smart drug’.

This article will be as based on fact and science as much as possible, taking material from authoritative sources such as medical publications, the Food and Drug Administration (FDA), and the National Health Service (NHS).

It aims to provide a balanced, fair assessment of modafinil’s side effects. As always, you can find our references at the end of the page.

Background: What is modafinil used for?

Modafinil, first synthesised in the 1970s, is a legitimate pharmaceutical used to treat sleep disorders like narcolepsy. It is similar in effects to Adrafinil.

Its wakefulness-promoting effects have led to it being used off-label by shift workers and students to stay up and study.

Modafinil is also believed by some to boost brainpower, improving concentration and memory, contributing further to its use by students and other academics.

When used in this way, the most common way to attain modafinil is either online through unlicensed pharmacies or through friends.

What are modafinil's side effects?

Common Modafinil side effects can include:

  • Headaches
  • Nausea
  • Nervousness
  • Stomach aches
  • Irritability
  • Weight loss
  • Arrhythmia (irregular heartbeat)

These side effects are quite common, and you see the same side effects from similar substances such as Adrafinil and Armodafinil.

One commonly reported side effect that is not mentioned here is modafinil side effects on the stomach. Often, users report having diarrhoea and having to use the toilet more often than usual.

Watch: Modafinil side effects - detailed breakdown

Teva, one of modafinil’s manufacturers, says that headaches may occur in ‘more than one in ten’ modafinil users.

Modafinil abuse can also lead to addiction - either psychologically or physically, so it is recommended to take breaks.

Rarer and more serious side effects of modafinil are suggested by the American FDA’s documentation on the drug. Rarer modafinil side effects include:

  • Depression
  • Anxiety
  • Hallucinations
  • Mania
  • Suicidal thoughts
  • Aggressive behaviour
  • Psychosis
  • Delusions
  • Skin rash (severe - to the point of hospitalisation)

Doctors warn that if you experience any of these symptoms then you should stop taking modafinil straight away.

Modafinil reviews corroborate these side effects.

As many users purchase modafinil online, from unregistered and unregulated pharmacies, you cannot guarantee that what you are getting is what you are told. Therefore side effects may vary.

Below is the chemical structure of Modafinil:

What are modafinil's long-term side effects?

The long-term effects and side effects of modafinil are also not fully known. The drug has not been around long enough for us to have researched it fully, meaning there might be issues that we aren’t aware of connected to extended use.

However, there is research on the effects extended modafinil use can have. A study has suggested that long-term use of modafinil can have "deeply concerning" effects, as it is believed to impair brain plasticity in young adults or adolescents. Given that students - mostly comprising younger people - are the most likely demographic to take the drug, this is a very relevant issue.

What is known, however, is that the longer you take modafinil, the more likely you are to experience the shorter-term side effects and they will, in fact, become more and more severe with increased usage.

As mentioned before, there isn't much data on the long-term effects, but the aforementioned study states that "modafinil could induce changes in plasticity or behavioural rigidity, and potentially damage WM [working memory], logical thinking and decision making," in young adults.

The best modafinil alternatives: Brainzyme vs modafinil

Because of the high risk of side-effects, we recommend that people who want to boost cognitive performance to use natural brain food supplements that provide similar effects but without the side-effects modafinil causes.

Our recommended brain food supplement is Brainzyme, which has been scientifically proven to support concentration, mental performance and the reduction of tiredness.

We've compared the effects below. 

Positive effects
o Helps concentration, motivation, wakefulness
o Works fast
o Helps concentration, motivation, wakefulness
o Works fast
Side effectso Hardly any side effects; some reports of feeling thirsty or going to the bathroom moreo Headache
o Dry mouth
o Sweating
o Tapping/restlessness
o Feeling antisocial – may be impatient/irritable
o Anxiety if not doing what you want to do
Wakefulnesso Helps maintain wakefulness and alertness for up to 8 hourso Keeps you awake for a long time
o Potentially longer than you want to
o Difficulty switching off
Focuso Helps give you the motivation and will to work, and aids in reducing distractions
o Assists in maintaining a natural focus
o Laser focus, which can be on the wrong task
o You may end up playing computer games, reading about irrelevant topics, etc
o Can be detrimental to studying
Stimulationo Calms and focuses the mindo Highly stimulating, causing agitation in some individuals
Toleranceo No issues with toleranceo May cause tolerance, needing increased doses to have the same effect
Availability/legalityo Readily available to buy
o Legal and natural for sporting use
o Only available by prescription
o Maybe screened for in sporting drugs tests


Both aid in motivation, better concentration and alertness.

Modafinil tends to be harsher, with more potential for side-effects which can lower productivity and hinder results in the long-term.

However, Brainzyme is smoother, and overall may yield more productivity and better results, especially over weeks and months.

You would need to decide for yourself which one is better for you, especially in light of the side-effects and other issues.

Conclusion & our recommended modafinil alternative

Taking all of the above into consideration, we would not recommend using modafinil if it is not prescribed to you by a medical professional. The serious side effects alone overshadow any positive effects you may get from using the drug.

This is why you should look into good alternatives. For a modafinil alternative to be effective, it must meet the following criteria:

  • Better value for money than modafinil
  • Equally or more effective than modafinil
  • Fewer side effects than modafinil
  • Legal to use over the counter

There are great alternatives available that meet all these requirements and cost less than modafinil.

Modafinil's mechanism of action is (by a large degree) to act on the brain neurotransmitter dopamine, of which one pathway has a major motivational component. It can, for some, also increase wakefulness and decrease appetite.

A safe, natural and fully legal UK alternative such as Brainzyme® Focus Pro works on the same pathway as modafinil (and thus has similar results with fewer side effects). 

Find out more about why we think Brainzyme is the best modafinil alternative here.

Brainzyme Focus Pro is a great modafinil alternative

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About the author

Benjamin Martin is a nootropic and brain supplement enthusiast

Benjamin Martin is a nootropic and brain supplement enthusiast who has tried every type of performance-boosting supplement under the sun. At Brainzyme, he uses his expertise to produce educational content for the Nootropics UK and Brain Supplements UK blogs.

Based in Edinburgh, Benjamin loves spending his free time in nature whenever he gets the chance.

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