Simtriyo (centanafadine) is used to treat attention deficit hyperactivity disorder (ADHD). ADHD is a brain disorder that affects how you pay attention, sit still, and control your behavior. ADHD cannot be prevented or cured. But there are medicines and other treatments you can use to help manage symptoms.
The FDA approved Simtriyo for ADHD in 2026. It contains the active ingredient centanafadine and belongs to a class of medicines known as stimulants.
Below are common questions and answers about Simtriyo for ADHD to help you learn if it may be a good treatment option for you.
How Does Simtriyo Work for ADHD?
It is not completely understood how Simtriyo works to help with ADHD symptoms. It is part of a group of medicines called stimulants. It may work by affecting levels of natural brain chemicals, such as dopamine, norepinephrine, and serotonin. These chemicals play a role in attention, alertness, and wakefulness. Normally, your brain releases these chemicals and then reabsorbs them. Simtriyo slows down that reabsorption, which means more of these chemicals stay available in your brain for longer. Experts believe this is how it helps improve ADHD symptoms.
How Do I Take Simtriyo?
Simtriyo comes as an extended-release capsule. It is usually taken once daily in the morning. Taking it at a consistent time helps keep a steady level of medicine in your body.
Take Simtriyo exactly as your health care provider tells you to. Your health care provider will decide the right dose for you or your child.
- Dose: In adults, treatment usually starts at 210 milligrams (mg) once daily, taken at about the same time each day. The dose may be increased to 280 mg once daily, based on how you respond and tolerate it. In children and teens, the dose is set by your health care provider. In children aged 6-12 years, the dose is based on body weight.
- With or without food: You can take Simtriyo with or without food. If it upsets your stomach, taking it with food may help.
- Swallowing the capsule: Do not crush, cut, or chew Simtriyo capsules. If you or your child cannot swallow the capsule whole, you can open it and sprinkle over a tablespoonful of applesauce or yogurt. You can also mix it in a tablespoonful of orange juice. This mixture should be swallowed right away, without chewing. Drink some water right after swallowing the mixture to wash everything down.
- Do not change your dose: Do not increase, decrease, or stop Simtriyo on your own, even if you feel well or feel it is not working.
- If you miss a dose: If you miss a dose and it is within four hours of when you normally take it, take the dose as soon as you remember it. If it has been more than four hours since you would normally take it, skip the missed dose and take your next dose at the usual time. Do not take double or extra doses. Do not take more than one dose each day.
How Was Simtriyo Studied for ADHD?
Several studies were done to see if Simtriyo was safe and effective to treat ADHD before it got FDA approval. Simtriyo was compared to a placebo (no medicine in it) in studies that lasted six weeks. Neither the study participants nor the investigators knew who was taking Simtriyo or placebo.
These studies were done in children (6-12 years old), teens (13-17 years old), and adults (18-55 years old). The main goal of these studies was to measure changes in participants’ ADHD symptoms after six weeks of treatment compared to scores before starting the study (baseline).
ADHD symptoms were measured using the following tools:
- ADHD Rating Scale Version 5 (ADHD-RS-5) was used in the children and teen studies.
- ADHD Investigator Symptom Rating Scale (AISRS) was used in the adult studies.
Both of these tools involve 18 questions that relate to 18 ADHD symptoms, including hyperactivity, impulsivity, and inattentive symptoms. In general, higher scores mean more frequent and more severe symptoms.
Below is a summary of the participant characteristics at the start of the studies:
Study 1: Children | Study 2: Teens | Study 3: Adults | Study 4: Adults | |
|---|---|---|---|---|
| Average Age in Years | 9 | 15 | 36 | 35 |
| Male | 58%
| 59%
| 51%
| 53% |
| Female | 42% | 41% | 49% | 47% |
Black/African American
| 27% | 25% | 14% | 13% |
| White | 65% | 70% | 81% | 79% |
| Other or Unreported Race | 8% | 5% | 5% | 8% |
| Hispanic or Latino Ethnicity | 31% | 28% | 22% | 18% |
What Benefits Were Seen?
The results of the four studies are reviewed below. Please note when reviewing the tables: A larger negative number means a bigger drop in ADHD symptom scores and more improvement. A negative “difference from placebo” means Simtriyo improved symptoms more than placebo did.
Studies in children and teens
After six weeks, children aged 6-12 years who took Simtriyo had a greater improvement in their ADHD symptoms (as measured by ADHD-RS-5) than those who took a placebo (no medicine in it). You can see the specifics in the table below.
| Study 1: Children Aged 6-12 | Placebo (151 participants) | Simtriyo Weight-Based Dose* |
|---|---|---|
| Average Baseline ADHD-RS-5 Score | 43 | 43 |
| Average Change From Baseline Score | -10.8 | -16.3 |
| Difference From Placebo | N/A | -5.6 |
*Simtriyo 280 mg was used for children weighing more than 50 kg (~110 pounds). A weight-based dose equivalent was used for children weighing less. Simtriyo 210 mg was used for children weighing 35-50 kg (~ 77-110 pounds), and Simtriyo 140 mg was used for children weighing between 20 and 35 kg (~44 and 77 pounds).
Similarly, after six weeks, teens aged 13-17 years had more improvement in their ADHD symptoms (as measured by ADHD-RS-5) than those who took a placebo. You can see the specifics in the table below.
| Study 2: Teens 13-17 | Placebo (145 participants) | Simtriyo 280 mg |
|---|---|---|
| Average Baseline ADHD-RS-5 Score | 37 | 37.9 |
| Average Change From Baseline Score | -14.2 | -18.5 |
| Difference From Placebo | N/A | -4.4 |
Adult studies
After six weeks, adults who took centanafadine (the active ingredient in Simtriyo) in a form believed to be equivalent to either 210 mg (low dose) or 280 mg (high dose) of Simtriyo had more improvement in their symptoms of ADHD as measured by AISRS than those who took a placebo. You can see the specifics in the table below.
| Study 3: Adults 18-55 | Placebo (144 participants) | Centanafadine Low Dose* | Centanafadine High Dose* |
|---|---|---|---|
| Average Baseline AISRS Score | 39.5 | 39.6 | 39.6 |
| Average Change From Baseline Score | -7 | -10.1 | -9.7 |
| Difference From Placebo | N/A | -3.2 | -2.7 |
| Study 4: Adults 18-55 | Placebo (141 participants) | Centanafadine Low Dose* | Centanafadine High Dose* |
| Average Baseline AISRS Score | 37.7 | 37.6 | 38.8 |
| Average Change From Baseline Score | -8.1 | -12.1 | -12.5 |
| Difference From Placebo | N/A | -4 | -4.4 |
*The adult studies used a slightly different form of the same active ingredient (centanafadine). Simtriyo is expected to work the same way at its matching doses: low dose for Simtriyo 210 mg and high dose for Simtriyo 280 mg.
All four studies pointed in the same direction: after six weeks, people taking Simtriyo had a bigger drop in their ADHD symptom scores than those taking placebo; this was true across children, teens, and adults.
Your own experience may be different. Your health care provider can help you decide whether Simtriyo is a good fit for you.
How Long Does It Take for Simtriyo to Work?
Based on what was seen in the studies, you may begin to notice some improvement in your symptoms within the first week or two of treatment. For many people, the effects continue to build gradually over about six weeks. It may take some time to see the full benefit.
Keep in mind that everyone responds differently. It is important to keep taking the medication as prescribed and stay in touch with your health care provider to check how Simtriyo seems to be working.
What Are Other Unique Considerations to Be Aware Of?
- Slowed growth: Children taking Simtriyo may be at a higher risk of not gaining height and weight as expected. In fact, Simtriyo is not recommended for children younger than 6 years. In early studies with Simtriyo, children younger than 6 had more weight loss than children 6 years or older. Regardless of your child’s age, keep all appointments with their health care provider to check your child’s height and weight before starting and during treatment with Simtriyo. Talk to your child’s health care provider if you have concerns about your child’s growth.
- Suicidal thoughts or actions: Simtriyo may increase the risk of suicidal thoughts or behaviors in children aged 6 and older, especially early in treatment. Watch for new or worsening changes in mood or behavior and contact your health care provider right away if you are concerned.
- Risk of misuse: Simtriyo can be misused and may lead to addiction, overdose, or death, especially if taken in higher doses or used in unapproved ways. Your health care provider will check your risk before you start Simtriyo and monitor you during treatment.
Note: As of August 2026, Simtriyo is still being reviewed by the DEA to decide how strictly it will be regulated as a controlled substance.
This is not a complete list of Simtriyo side effects. Tell your prescriber or seek medical care if you have any symptoms that feel severe or do not go away.
