Qelbree (viloxazine) is a prescription drug that’s used to treat attention deficit hyperactivity disorder (ADHD). Qelbree can cause side effects that range from mild to serious. Examples include headache and constipation.

Qelbree is prescribed for use in adults and some children to treat ADHD.

The active ingredient in Qelbree is viloxazine. (An active ingredient is what makes a drug work.) The drug comes as an extended-release (ER) capsule. ER means the drug is released into your body slowly over a period of time.

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

Some people may experience mild to serious side effects during Qelbree treatment. Examples of the drug’s more commonly reported side effects include:

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

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

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

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

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

Serious side effects have been reported with Qelbree. These include:

* Qelbree has a boxed warning for this side effect. This is the most serious warning from the Food and Drug Administration (FDA). To learn more, see the “Side effects explained” section below.
† To learn more about this side effect, see the “Side effects explained” section below.
‡ An allergic reaction from Qelbree is possible, but it wasn’t reported in studies.

If you develop serious side effects while taking Qelbree, call your doctor right away. If they seem life threatening or you think you’re having a medical emergency, immediately call 911 or your local emergency number.

Note: After the Food and Drug Administration (FDA) approves a drug, it tracks side effects of the medication. If you’d like to notify the FDA about a side effect you’ve had with Qelbree, visit MedWatch.

Qelbree may be used in children ages 6 years and older. The drug can cause similar side effects in adults and children. Examples of these are described throughout this article.

Many of Qelbree’s side effects are more common in adults, though children are more likely to experience sleepiness. In studies, this was the most common side effect reported in children taking this drug. (To learn more about this, see “Side effects explained” below.)

Also, children who take Qelbree may not gain as much weight as would be expected for their ages. So, they should have their weight checked frequently by their doctor. (To learn more about this, see “Does Qelbree cause weight loss?” in the FAQ section below.)

On the other hand, insomnia (trouble sleeping), fatigue (low energy), headache, and nausea occurred more often in adults than in children taking Qelbree.

Many factors can affect your risk of side effects with this drug. These include the dosage you take, other health conditions you may have, and other drugs you take. For more information about how Qelbree may affect you personally, talk with your doctor.

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

Do Qelbree’s side effects go away?

Yes, side effects from Qelbree usually improve or go away as your body gets used to the drug. Qelbree isn’t known to have any long-term side effects.

If you have bothersome side effects that don’t get better in a few days to weeks, talk with your doctor. They may reduce your dose to see if this helps. If you still have troublesome side effects, they may recommend a different treatment. Qelbree side effects usually go away soon after stopping the drug.

If you’re concerned about side effects from Qelbree, talk with your doctor.

Does Qelbree cause weight loss?

It can. Qelbree can cause reduced appetite and nausea, which can lead to weight loss in some people. But this wasn’t reported in adults who took Qelbree in studies.

However, reduced appetite and nausea could prevent children from gaining as much weight as would be expected for their ages. In short-term studies, children ages 12 to 17 years who took Qelbree lost a small amount of weight.

For comparison, children of the same age who took a placebo (a treatment with no active drug) gained weight. In these studies, children ages 6 to 12 years who took Qelbree didn’t gain as much weight as children who took a placebo.

It’s not known if Qelbree can affect weight and growth in children who take it for long periods of time. Children who take Qelbree should have their weight regularly checked by their doctor. If the child isn’t gaining weight as would be expected for their age, their doctor may recommend they stop Qelbree and try a different ADHD treatment.

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

Risk of suicidal thoughts and behaviors

Qelbree has a boxed warning for a risk of suicidal thoughts and behaviors. A boxed warning is the most serious warning from the Food and Drug Administration (FDA). It alerts doctors and patients about drug effects that may be dangerous.

In studies, some adults and children who took Qelbree had suicidal thoughts or behavior, but this was rare. There were no suicide attempts reported in these studies.

Some people may have signs that occur before suicidal thoughts or behavior develop. These include changes in mood, feelings, thoughts, or behavior. Examples include the following, especially if these are new, sudden, severe, or worsening:

What might help

If you or your child take Qelbree, you should watch for unusual changes in mood, feelings, thoughts, or behavior. You can ask family members, friends, and teachers to watch for these changes as well. This is especially important in the first few months of treatment and after any dosage changes.

If you or your child have changes in mood or behavior such as those listed above, talk with your doctor right away. But if the symptoms worry you, or you or your child have thoughts about suicide, call 911 or get emergency medical help.

If you have suicidal thoughts or behavior, your doctor will likely have you stop taking Qelbree.

Help is out there

If you or someone you know is in crisis and considering suicide or self-harm, please seek support:

If you’re calling on behalf of someone else, stay with them until help arrives. You may remove weapons or substances that can cause harm if you can do so safely.

If you are not in the same household, stay on the phone with them until help arrives.

Headache

Headaches were a commonly reported side effect in studies of Qelbree. These included migraine and tension headaches and were more common in adults than in children.

What might help

If you have a headache with Qelbree, it may help to have a nap, drink of water, or a snack. Headaches can sometimes be triggered by not getting enough sleep, fluids, or food. And Qelbree can sometimes cause trouble sleeping, nausea, and reduced appetite.

If you have bothersome headaches with Qelbree, it’s generally safe to take a pain reliever, such as ibuprofen (Advil, Motrin) or acetaminophen (Tylenol). But you should avoid taking pain relievers that contain caffeine because Qelbree can stop your body from breaking it down as well as usual. This can increase your risk of caffeine-related side effects, such as insomnia (trouble sleeping) and anxiety.

If you want to take a pain reliever, ask your pharmacist to recommend one that’s suitable. But if you have frequent or severe headaches with Qelbree, talk with your doctor. They may reduce your dosage or recommend you switch to a different ADHD treatment.

Constipation

Some people may have constipation while taking Qelbree. But this side effect wasn’t common in adults who took Qelbree in studies. And it wasn’t reported in children who took the drug.

What might help

If you have constipation with Qelbree, make sure you’re drinking enough fluids and eating enough fiber. This drug can sometimes cause nausea and reduced appetite, which may cause you to drink less fluids or eat less fiber than usual.

If drinking more water, eating extra fiber, and getting regular exercise don’t help manage your constipation, ask your pharmacist to recommend a laxative.

If you have constipation that’s bothersome or severe, talk with your doctor. They may reduce your Qelbree dosage or recommend you switch to a different ADHD treatment.

Sleepiness

You may have sleepiness while taking Qelbree. This side effect was commonly reported in the drug’s studies and was more common in children than adults.

Qelbree can also cause fatigue (low energy), but this was more common in adults than children. Fatigue could be related to insomnia, which is another side effect of Qelbree, especially in adults.

What might help

If you feel sleepy, you should avoid activities such as driving or operating machinery. And children should avoid riding bikes and other activities that could be dangerous when sleepy.

If you have sleepiness that’s bothersome, talk with your doctor. They may suggest taking your daily dose in the evening instead of the morning. This may help improve daytime sleepiness.

If you have daytime fatigue related to trouble sleeping, your doctor may suggest taking your daily dose in the morning rather than the evening. This may help you sleep better at night, which can improve your energy levels during the day.

If changing the time you take Qelbree doesn’t help, your doctor may reduce your dosage. Or they may recommend you switch to a different ADHD treatment.

Increased blood pressure and heart rate

Qelbree may cause a mild increase in your blood pressure and heart rate. In the drug’s studies, these side effects were common in both adults and children.

A mild increase in blood pressure doesn’t usually cause symptoms. But having consistently high blood pressure could increase your risk of heart problems, such as a heart attack.

Severe high blood pressure can cause symptoms such as flushing (temporary warmth, redness, or deepening of skin color) or dizziness. But Qelbree isn’t likely to increase your blood pressure enough to cause symptoms.

If you have an increased heart rate, you may feel like your heart is racing or pounding. Some people may also have chest pain, shortness of breath, or dizziness.

What might help

To make sure Qelbree is safe for you, your doctor will check your pulse and blood pressure before prescribing it. If you already have high blood pressure or a fast heart rate, your doctor may not prescribe this drug for you.

During treatment with Qelbree, your doctor will monitor your heart rate and blood pressure. If they get too high, your doctor may reduce your dosage or have you switch to a different ADHD treatment.

Allergic reaction

Like most drugs, Qelbree can cause an allergic reaction in some people. But this side effect wasn’t reported in studies. 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:

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

If you have symptoms of a severe allergic reaction, such as swelling or trouble 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 Qelbree, they may have you switch to a different treatment.

Keeping track of side effects

During your Qelbree 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

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

Qelbree may not be suitable for everyone. It comes with some warnings, including a boxed warning.

Boxed warning: Risk of suicidal thoughts and behaviors

Qelbree has a boxed warning for the risk of suicidal thoughts and behaviors. A boxed warning is the most serious warning from the Food and Drug Administration (FDA). To learn more, see the “Side effects explained” section above.

Other warnings

Qelbree may not be right for you if you have certain medical conditions. This is known as a drug-condition interaction. Other factors may also affect whether this drug is a good treatment option for you. Talk with your doctor about your health history before starting Qelbree. Factors to consider include those described below.

High blood pressure. Qelbree can increase your blood pressure. If you already have high blood pressure, this drug could make it worse or harder to manage. Your doctor will determine whether Qelbree is safe for you. If they prescribe it for you, they’ll check your blood pressure frequently. If needed, they may prescribe a blood pressure medication for you or adjust the dosage of any you already take.

Heart problems. Qelbree can increase your heart rate. This drug may not be safe for you if you already have a fast heart rate or other heart problems, such as angina. If your doctor determines Qelbree is safe for you and prescribes it, they’ll check your heart frequently during your treatment.

Depression or bipolar disorder. Qelbree may increase the risk of manic episodes in people with bipolar disorder. (Manic episodes are periods of extreme excitement and energy.)

Qelbree may also cause suicidal thoughts or behaviors, but these are rare. Talk with your doctor if you or a family member have a history of mental health conditions, especially depression, mania, bipolar disorder, or suicidal thoughts. Your doctor will determine whether Qelbree is safe for you.

Kidney problems. Your kidneys help remove Qelbree from your body. If you have severe kidney problems, the drug could build up in your system, which could increase your risk of side effects. Due to this risk, your doctor will likely prescribe a Qelbree dosage for you that’s lower than usual.

Allergic reaction. If you’ve had an allergic reaction to Qelbree or any of its ingredients, your doctor will likely not prescribe it for you. Ask them about other medications that might be better options.

Other medications. Taking certain other drugs with Qelbree can increase your risk of side effects. Because of this,your doctor may not prescribe Qelbree if you take certain other drugs, such as the monoamine oxidase inhibitor (MAOI) phenelzine (Nardil). Before starting treatment with Qelbree, be sure to tell your doctor about any other medications you take.

Alcohol and Qelbree

Your doctor may recommend that you avoid or limit alcohol consumption while taking Qelbree. Consuming alcohol with Qelbree could increase your risk of certain side effects of the drug, including headache, sleepiness, nausea, and dizziness. Drinking strong alcohol with Qelbree could also make the drug less effective.

If you drink alcohol, talk with your doctor about how much, if any, is safe to consume with Qelbree.

Pregnancy and breastfeeding while taking Qelbree

It’s not known whether Qelbree is safe to take during pregnancy or while breastfeeding. If you’re pregnant, breastfeeding, or planning to become pregnant or breastfeed, talk with your doctor about possible risks and benefits of Qelbree.

If you decide to take Qelbree during pregnancy, you’re encouraged to sign up for the National Pregnancy Registry for Psychiatric Medications. This registry collects health information about people who take psychiatric medications during pregnancy and the health of their children. It aims to help doctors and pregnant people make informed decisions about treatments. Your doctor can tell you more.

Qelbree has some common side effects but they’re usually mild and easily managed. As with many drugs, Qelbree can also cause some serious side effects, but these are rare. Most people take this medication without any problems.

To find out more about Qelbree’s side effects, talk with your doctor. Some examples of questions you may want to ask include:

  • Can Qelbree cause sexual difficulties?
  • Does my risk of side effects depend on the dosage I take?
  • How do the side effects of Qelbree compare with other drugs for ADHD, such as atomoxetine (Strattera) and methylphenidate (Ritalin)?
  • If my job requires driving or operating machinery, is it safe for me to take Qelbree?

To learn more about Qelbree, 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.