Mydayis (mixed amphetamine salts) is a prescription drug for treating ADHD. Mydayis can cause side effects that range from mild to serious. Examples include insomnia, weight loss, and decreased appetite.

Specifically, Mydayis is prescribed to treat attention deficit hyperactivity disorder (ADHD) in adults and children ages 13 years and older.

The active ingredient in Mydayis is mixed amphetamine salts. (An active ingredient is what makes a drug work.) The drug comes as an extended-release oral capsule. “Extended release” means the drug is slowly released into your body over a long period of time.

Keep reading to learn about the common, mild, and serious side effects that Mydayis can cause. For a general overview of the drug, including details about its uses, see this article.

Some people may experience mild to serious side effects during their Mydayis treatment. Here are only a few examples of the drug’s commonly reported side effects:

* To learn more about this side effect, see the “Side effects explained” section below.

Mild side effects have been reported with Mydayis. These include:

In most cases, these side effects should be temporary. And some may be easily managed. But if you have symptoms that are ongoing or bothersome, talk with your doctor or pharmacist. And do not stop taking Mydayis unless your doctor recommends it.

Mydayis may cause mild side effects other than those listed above. See the drug’s prescribing information for details.

* To learn more about this side effect, see the “Side effects explained” section below.
† An allergic reaction is possible after taking Mydayis. But this side effect was not reported in studies of the drug.

Serious side effects can occur with Mydayis. These include:

If you develop serious side effects while taking Mydayis, call your doctor right away. If the side effects seem life threatening or you think you have a medical emergency, immediately call 911 or your local emergency number.

* To learn more about this side effect, see the “Mydayis and misuse” section below.
† An allergic reaction is possible after taking Mydayis. But this side effect was not reported in studies of the drug.

Note: After the FDA approves a drug, it tracks and reviews side effects of the medication. If you’d like to notify the FDA about a side effect you’ve had with Mydayis, visit MedWatch.

Mydayis is prescribed to treat ADHD in children ages 13 and older. In studies of the drug, side effects were similar for children and adults. However, children were more likely to experience nausea, upper abdominal pain, and dizziness compared with adults.

Also, slowed growth is commonly reported in children taking amphetamines (such as Mydayis) to treat ADHD. Slowed growth can lead to a lower weight and shorter height than the average measurements for other children their age.

During your child’s Mydayis treatment, their doctor will keep track of their height and weight. If your child’s growth shows signs of being affected, their doctor may recommend temporarily stopping Mydayis treatment.

For more information about possible side effects in children taking Mydayis, talk with your child’s doctor or a pharmacist.

Get answers to some frequently asked questions about Mydayis’s side effects.

How do side effects of Mydayis compare with those seen with Vyvanse or Adderall XR?

Mydayis, amphetamine/dextroamphetamine (Adderall XR), and lisdexamfetamine (Vyvanse) are all prescription drugs for treating ADHD. They all belong to the same group of drugs: central nervous system stimulants.

These drugs have many of the same side effects, including:

  • anxiety or nervousness
  • nausea and vomiting
  • decreased appetite
  • weight loss
  • insomnia

If you have questions about how side effects of these drugs compare, talk with your doctor or pharmacist. You can also see these articles to learn more about the side effects of Vyvanse and Adderall XR.

Does Mydayis cause long-term side effects?

In studies of Mydayis, long-term side effects were not reported. However, it’s important to note that these studies only lasted 4–7 weeks.

Although long-term side effects weren’t reported in studies, there have been reports of long-term side effects with amphetamines such as Mydayis after the drugs became available for prescription. Examples of these long-term side effects include:

Side effects of Mydayis usually ease as your body adjusts to the medication. Stopping treatment will likely result in a quick reduction in side effects. To learn more about the possible long-term side effects of Mydayis, talk with your doctor or pharmacist.

* Mydayis has a boxed warning for this side effect. To learn more, see the “Mydayis and misuse” section below.

Learn more about some of the side effects Mydayis may cause.

Insomnia

Mydayis may cause insomnia. This was a common side effect reported in studies of the drug.

Insomnia may cause symptoms such as:

  • fatigue (low energy)
  • feeling irritable
  • headache
  • daytime sleepiness
  • reduced performance at work or school
  • difficulty falling asleep or staying asleep through the night
  • waking up multiple times during the night
  • waking up too early

Factors that can increase the risk of insomnia with Mydayis include:

  • using alcohol, nicotine, or caffeine before bedtime
  • using electronics before bedtime
  • not having a consistent bedtime
  • eating before bedtime

What might help

If you have difficulty sleeping during your Mydayis treatment, you may want to try:

  • reading or listening to music instead of using electronics
  • avoiding snacks, caffeine, nicotine, or alcohol before bedtime
  • setting a bedtime schedule
  • keeping your bedroom quiet, dark, and a cool temperature

If you’re still having difficulty sleeping, talk with your doctor. They may recommend another treatment option. But you should not stop taking Mydayis without talking with your doctor first.

Decreased appetite

Some people experience decreased appetite while taking Mydayis. This was a common side effect reported in studies of the drug.

Decreased appetite may cause symptoms such as:

  • weight loss
  • feeling irritable
  • fatigue
  • weakness
  • headache

Certain factors may increase your risk of a decreased appetite with Mydayis. These include:

  • having chronic diseases that suppress appetite, such as dementia (problems with thinking, communication, and memory), cancer, liver disease, or kidney disease
  • taking other prescription drugs, over-the-counter drugs, or supplements that decrease appetite

What might help

If you have a decreased appetite during your Mydayis treatment and that concerns you, you may want to try:

  • eating a large breakfast, then taking your dose
  • having a set eating schedule
  • choosing nutritious, high calorie foods
  • staying hydrated by drinking plenty of water
  • avoiding exercise 1 hour before eating

Allergic reaction

Like most drugs, Mydayis can cause an allergic reaction in some people. However, this was not reported in studies of the drug. But there have been reports of allergic reactions after Mydayis became available for prescription.

Symptoms can be mild to serious and can include:

  • skin rash
  • itchiness
  • flushing (temporary warmth, redness, or deepening of skin color)
  • swelling under your skin (usually in your eyelids, lips, hands, or feet)
  • swelling of your mouth, tongue, or throat, which can make it hard to breathe

What might help

If you have mild symptoms of an allergic reaction, such as a mild rash, call your doctor right away. They may suggest a treatment to manage your symptoms. Examples include:

  • an oral antihistamine, such as diphenhydramine (Benadryl)
  • a product you apply to your skin, such as hydrocortisone cream

If your doctor confirms you’ve had a mild allergic reaction to Mydayis, they’ll decide whether you should continue taking it.

If you have symptoms of a severe allergic reaction, such as swelling or difficulty breathing, call 911 or your local emergency number right away. These symptoms could be life threatening and require immediate medical care.

If your doctor confirms you’ve had a serious allergic reaction to Mydayis, they may have you switch to a different treatment.

Keeping track of side effects

During your Mydayis treatment, consider taking notes on any side effects you’re having. You can then share this information with your doctor. This is especially helpful when you first start taking a new drug or using a combination of treatments.

Your side effect notes can include things such as:

  • what dose of the drug you were taking when you had the side effect
  • how soon you had the side effect after starting that dose
  • what your symptoms were
  • how your symptoms affected your daily activities
  • what other medications you were taking
  • any other information you feel is important

Keeping notes and sharing them with your doctor will help them learn more about how Mydayis affects you. They can then use this information to adjust your treatment plan if needed.

Below is important information you should consider before taking Mydayis.

Boxed warning: Risk of misuse and addiction

Mydayis has a boxed warning for the risks of misuse and addiction. A boxed warning is the most serious warning from the FDA.

To learn more, see the “Mydayis and misuse” section below.

Other warnings

Mydayis can sometimes cause harmful effects in people who have certain conditions. This is known as a drug-condition interaction. Other factors may also affect whether Mydayis is a good treatment option for you.

Talk with your doctor about your health history before you take Mydayis. Be sure to tell them if any of the following factors apply to you:

Alcohol and Mydayis

You should not drink alcohol during Mydayis treatment.

Drinking alcohol with Mydayis can cause your body to absorb more of the drug more quickly than usual. This may raise your risk of side effects from the drug. It can also increase your risk of overdose.

If you have questions about consuming alcohol during Mydayis treatment, talk with your doctor or pharmacist.

Pregnancy and breastfeeding with Mydayis

Before starting Mydayis treatment, it’s important to talk with your doctor if you’re pregnant, breastfeeding, or planning to become pregnant or to breastfeed.

Pregnancy

It’s not known whether it’s safe to take Mydayis during pregnancy. But there have been reports of premature delivery or low birth weight in children born to people who took drugs similar to Mydayis during pregnancy.

If you’re able to become pregnant, your doctor may recommend using a form of birth control during your Mydayis treatment.

If you take Mydayis while pregnant, consider signing up for the National Pregnancy Registry for Psychiatric Medications. A pregnancy registry collects information about the safety of certain drugs when taken during pregnancy. You can learn more or sign up on the registry website or by calling 1-866-961-2388.

Breastfeeding

Mydayis is not safe to take while breastfeeding. The drug can pass into breast milk. A child exposed to Mydayis through breast milk may have a higher risk of heart problems, slowed growth rate, and blood circulation disorders.

If you’re breastfeeding or planning to do so, talk with your doctor about your options.

Mydayis has a boxed warning for the risks of misuse and addiction.* Mydayis is a Schedule II controlled substance, which means it carries a high risk of misuse. Examples of misuse include taking the drug more often or at higher doses than prescribed by your doctor.

Before prescribing Mydayis, your doctor will assess your risk of misuse and addiction. While you’re taking this medication, your doctor will also monitor you for signs of misuse or addiction.

You should take Mydayis only as your doctor has prescribed. Misuse increases the risk of developing substance use disorder and overdose. Symptoms of Mydayis overdose include:

  • feeling restless, jittery, or shaky
  • panic attack
  • flu-like symptoms
  • fast breathing
  • agitation, confusion, and hallucinations
  • body temperature higher than 104°F (40°C)
  • seizures
  • fast and irregular heart rate, which may lead to heart attack or stroke

An overdose of Mydayis may even lead to coma or be fatal.

Call your doctor if you think you’ve taken too much Mydayis. You can also call 800-222-1222 to reach America’s Poison Centers or use its online resource. But if you have severe symptoms, immediately call 911 (or your local emergency number) or go to the nearest emergency room.

It’s important to note that you should never share Mydayis, even if someone else has symptoms similar to yours. Your doctor or pharmacist can explain how to store and dispose of Mydayis correctly.

* Misuse refers to taking a drug in a way other than how a doctor prescribes it. With addiction, a drug is taken even if it’s causing harmful outcomes.

Like most drugs, Mydayis can cause side effects that range from mild to serious. However, most are temporary and go away after a few days to weeks. If you have questions about side effects that Mydayis can cause, talk with your doctor.

Examples of questions you may want to ask include:

  • Which side effects of Mydayis should be addressed right away?
  • Does Mydayis have fewer side effects than other ADHD medications?
  • Can you lower my dose of Mydayis if I have bothersome side effects?

To learn more about Mydayis, see these articles:

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Disclaimer: Healthline has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.