Mydayis XR Side Effects: What to Expect and When to Call Your Doctor

Starting a new ADHD medication always comes with questions — and Mydayis XR is no exception. Knowing what side effects to expect, which ones usually go away on their own, and which ones require immediate medical attention can make the difference between a successful treatment experience and an unnecessary scare.

This guide covers everything you need to know about Mydayis XR side effects in plain language — from the most common to the most serious.

Most Common Mydayis XR Side Effects

In clinical trials, the most frequently reported side effects in adults taking Mydayis (occurring in at least 5% of patients at twice the rate of placebo) were:

• Insomnia — Difficulty falling or staying asleep. Because Mydayis can last up to 16 hours, this is especially important. Taking your dose as early as possible in the morning (immediately upon waking) helps minimize this effect.
• Decreased appetite — Very common with stimulants. Many people find they're not hungry during the day but get hungrier in the evenings after the medication wears off. Eating a nutritious breakfast before taking your dose can help.
• Weight loss — Often a result of reduced appetite. Your doctor may monitor your weight, especially in adolescents. Some patients find this side effect improves as their body adjusts.
• Dry mouth — Staying well hydrated throughout the day usually helps. Chewing sugar-free gum can also provide relief.
• Increased heart rate — Mild elevations in heart rate are common with stimulants. Your doctor will monitor your pulse, especially early in treatment.
• Anxiety — Some people notice increased nervousness, especially at higher doses. If anxiety becomes problematic, talk to your doctor about a dose adjustment.

In adolescents (ages 13–17), the most common side effects were insomnia, decreased appetite, decreased weight, irritability, and nausea — slightly different from the adult profile.

Side Effects That Usually Improve Over Time

Many of the common side effects improve significantly as your body adjusts to the medication — usually within the first 2–4 weeks. These include:

• Nausea (especially if taken without food)
• Headache
• Mild stomach upset
• Jitteriness or restlessness, especially in the first few days

If these symptoms don't improve after a few weeks, or if they significantly affect your quality of life, contact your prescriber. A dose adjustment is often all it takes.

Serious Side Effects: When to Call Your Doctor Right Away

Some side effects are rare but serious. Contact your doctor immediately — or call 911 — if you experience any of the following:

• Chest pain, shortness of breath, or fainting — These may signal a serious heart problem. Sudden death, stroke, and heart attack have been reported in adults taking CNS stimulants at recommended doses.
• Significantly elevated blood pressure — Stimulants can cause mild increases in blood pressure. Severe or persistent elevations need immediate attention.
• Hallucinations, paranoia, or new psychotic symptoms — Mydayis may trigger or worsen psychotic or manic symptoms, even in people with no prior psychiatric history.
• Signs of serotonin syndrome — Agitation, confusion, rapid heart rate, muscle stiffness or twitching, sweating, high fever, or seizures. This can occur if Mydayis is combined with certain other medications (see our drug interactions guide for details).
• Numbness, pain, or color changes in fingers or toes — This could indicate Raynaud's phenomenon, a rare but real side effect of stimulant medications. Fingers or toes may turn pale, blue, then red.
• Seizures — Mydayis may lower the seizure threshold. If you experience a seizure, stop taking the medication and contact your doctor immediately.
• Thoughts of self-harm or suicide — Any new or worsening mood symptoms or suicidal thoughts require urgent medical attention.

Side Effects Specific to Mydayis's 16-Hour Duration

Because Mydayis lasts significantly longer than other ADHD medications, some side effects may feel more pronounced or linger longer:

• Insomnia is more likely if taken any time other than first thing in the morning. Even a mid-morning dose can push the medication's effects well into nighttime.
• Appetite suppression may last into the evening, making dinner difficult. Planning larger meals at breakfast and eating lighter but more nutritious snacks through the day can help.
• Side effects from a missed dose — If you miss your morning dose and realize it later in the day, do NOT take it. A late dose risks keeping you awake all night. Skip it and resume the next morning.

Alcohol and Mydayis: Important Warning

Do not drink alcohol while taking Mydayis. Lab testing has shown that alcohol increases the rate at which amphetamine is released from Mydayis capsules — meaning you could absorb significantly more medication than intended. This raises the risk of all side effects, including dangerous ones. Avoid alcohol entirely while on this medication.

What to Do If Side Effects Are Bothering You

If side effects are interfering with your daily life, don't stop the medication without talking to your doctor first — abrupt changes can cause rebound symptoms. Instead, call your provider and discuss:

• Lowering the dose (common with anxiety, insomnia, or heart rate increases)
• Taking the dose earlier in the morning to reduce insomnia
• Switching to a different ADHD medication if side effects don't improve

If you need to switch medications, see our guide on alternatives to Mydayis XR. And if you're struggling to find Mydayis in stock, Medfinder can help you locate a pharmacy with availability.