ADHD Medication Side Effects in Adults: What Labels Say

Written by the practice's editorial team. Published October 19, 2026; updated October 19, 2026. Part of the Adult ADHD Medication Guide, understand section. Medically reviewed by John C. Shershow, M.D. on October 19, 2026. Editorial policy

Key points

In the adult Adderall XR trial in its FDA label, 35% of people on the drug reported dry mouth and 33% loss of appetite, compared with 5% and 3% on placebo.
In two adult Concerta trials, decreased appetite (25% vs 7%), headache (22% vs 16%) and dry mouth (14% vs 4%) were the most common side effects.
Stimulant labels state that blood pressure rises by a mean of about 2 to 4 mm Hg and heart rate by about 3 to 6 beats per minute, and call for monitoring.
Since 2023, every prescription stimulant label carries a boxed warning about abuse, misuse and addiction.
Medication Guides tell patients to call the prescriber or go to the nearest emergency room right away for chest pain, shortness of breath or fainting.

Most adults who take ADHD medication notice some side effects, and most of those are mild. A smaller set of effects is serious and needs a fast response. This page sorts the two, using the FDA labels for the medications most often prescribed to adults (checked on DailyMed on October 19, 2026) and a large research review. It does not give doses, and it is not advice to start, stop or change any medication. Decisions about a specific medication belong to you and your prescriber.

Why label numbers need a caveat

The percentages below come from short placebo-controlled trials printed in each label. The Adderall XR label itself warns that rates seen in the trials of one drug "cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice." Use the table to see which effects are common for each medication, not to rank one medication against another. The placebo column matters too: some people on placebo also report headaches, poor sleep and anxiety.

Common side effects in adult trials

Medication (adult trial in the label)	Most common side effects (drug vs placebo)
Adderall XR (mixed amphetamine salts), 4-week trial	Dry mouth 35% vs 5%; loss of appetite 33% vs 3%; insomnia 27% vs 13%; headache 26% vs 13%; weight loss 10% vs 0%; anxiety 8% vs 5%; fast heart rate 6% vs 3%
Vyvanse (lisdexamfetamine), 4-week trial	Decreased appetite 27% vs 2%; insomnia 27% vs 8%; dry mouth 26% vs 3%; diarrhea 7% vs 0%; nausea 7% vs 0%; anxiety 6% vs 0%
Concerta (methylphenidate ER), two trials	Decreased appetite 25% vs 7%; headache 22% vs 16%; dry mouth 14% vs 4%; nausea 13% vs 3%; insomnia 12% vs 6%; anxiety 8% vs 2%; irritability 6% vs 1%
Strattera (atomoxetine), pooled studies up to 25 weeks	Nausea 26% vs 6%; dry mouth 20% vs 5%; decreased appetite 16% vs 3%; insomnia 15% vs 8%; fatigue 10% vs 6%; erectile dysfunction 8% vs 1% (men); urinary hesitation 6% vs 1%
Qelbree (viloxazine), flexible-dose trial	Insomnia 23% vs 7%; headache 17% vs 7%; nausea 12% vs 3%; fatigue 12% vs 3%; dry mouth 10% vs 2%; decreased appetite 10% vs 3%; sleepiness 6% vs 2%

Two patterns stand out. Stimulants mostly cause appetite loss, dry mouth and sleep trouble. The nonstimulants atomoxetine and viloxazine more often cause nausea and tiredness, and atomoxetine causes sexual and urinary side effects in some men. Each of these has its own page in this guide: sleep, appetite and weight and anxiety.

How often side effects lead people to stop

Side effects are the main reason adults drop out of medication trials. In the adult Adderall XR study, 12% of people on the drug left the trial because of adverse events, compared with 1.6% on placebo; insomnia was the most frequent reason. The Concerta label lists anxiety, irritability, insomnia and increased blood pressure as the most common reasons for discontinuation across its trials.

A 2018 network meta-analysis in Lancet Psychiatry (Cortese and colleagues) pooled tolerability data on 5,362 adults. Amphetamines, methylphenidate and atomoxetine all had more dropouts due to side effects than placebo. The same review found all three more effective than placebo for adult ADHD symptoms, which is why the trade-off is weighed person by person.

Serious warnings on stimulant labels

Stimulants include amphetamine products (Adderall, Adderall XR, Mydayis, Vyvanse and others) and methylphenidate products (Ritalin, Concerta, Focalin and others). Their labels share these warnings:

Abuse, misuse and addiction. In 2023 the FDA required the boxed warning on all prescription stimulants to describe these risks, including overdose and death with misuse. See misuse and addiction risk.
Heart. Sudden death has been reported in people with structural heart problems or other serious heart disease. Labels advise avoiding stimulants in people with known serious heart disease. Blood pressure and pulse rise on average, and labels call for monitoring. The full evidence is in ADHD medication, heart health and blood pressure.
Psychotic or manic symptoms. Stimulants can cause hallucinations, delusional thinking or mania even in people with no history of them. In pooled trials this happened in about 0.1% of people on stimulants and 0% on placebo. Labels also ask prescribers to screen for bipolar disorder risk first.
Circulation in fingers and toes. Peripheral vasculopathy, including Raynaud's phenomenon, can make fingers or toes numb, cold, painful or change color. It is usually mild, but labels describe rare skin sores.
Seizures. Stimulants may lower the seizure threshold, mainly in people with a history of seizures or abnormal EEGs.
Tics. New or worsening motor and verbal tics, including Tourette's syndrome, are listed.
Serotonin syndrome (amphetamines). The risk rises when amphetamines are combined with SSRIs, SNRIs, triptans and other serotonergic drugs. See drug interactions.
Methylphenidate-specific warnings. The Concerta label adds priapism (painful or prolonged erections), acute angle closure glaucoma, increased eye pressure, and a risk of blockage in people with severe narrowing of the gut, because the tablet does not change shape.

Serious warnings on nonstimulant labels

Atomoxetine (Strattera). A boxed warning covers suicidal thoughts in pediatric patients 6 and older. The label says a similar analysis in adults "did not reveal an increased risk." Other warnings: rare severe liver injury, increases in blood pressure and heart rate, urinary retention, priapism, and new psychotic or manic symptoms.
Viloxazine (Qelbree). Its boxed warning on suicidal thoughts and behaviors applies to adults too: in the adult trial, 3 of 189 people on the drug (1.6%) reported suicidal ideation, compared with none of 183 on placebo. The label also warns about higher heart rate and diastolic blood pressure, mania in people with bipolar disorder, and sleepiness that can affect driving.

Off-label options such as bupropion and guanfacine have their own warning sets, covered on the bupropion and guanfacine and clonidine pages.

When to call the prescriber and when to get emergency care

The Medication Guides that come with each prescription spell out which symptoms need a call and which need emergency care. This summary follows their wording.

Symptom	What the label or guidance says to do
Chest pain, shortness of breath or fainting	Call the prescriber or go to the nearest hospital emergency room right away (stimulant Medication Guides). The Strattera guide says to get medical help right away.
Thoughts of suicide or self-harm, or sudden changes in mood or behavior	Call the prescriber right away or get emergency help (Qelbree, Strattera). For immediate support, call or text 988. If there is immediate danger, call 911.
Agitation, hallucinations, fast heartbeat, fever, heavy sweating, tremor, muscle stiffness or twitching, especially after adding another medication	These can be signs of serotonin syndrome, which the label calls potentially life-threatening. Go to the nearest emergency room right away.
An erection that is painful or lasts too long	Get medical help right away (Concerta, Strattera).
Swelling of the face, lips or throat, or trouble breathing	These can be signs of a severe allergic reaction (anaphylaxis), which is an emergency. Call 911.
Taking too much medication	Call Poison Help at 1-800-222-1222 or go to the nearest emergency room right away.
Hearing voices, seeing or believing things that are not real, or new manic symptoms	Call the prescriber right away.
Itching, dark urine, yellow skin or eyes, or unexplained flu-like symptoms on atomoxetine	Tell the prescriber right away; liver tests may be needed.
Eye pain, redness, swelling or vision changes on methylphenidate	Call the prescriber right away.
Unexplained sores on fingers or toes	Call the prescriber right away.
Poor sleep, low appetite, headache, dry mouth, mild nausea	Bring them up with the prescriber, sooner if they are getting worse or affecting daily life.

Keep any changes to the medication itself in the prescriber's hands, including when a side effect is the reason. Side effects can often be addressed by timing, formulation or a different medication, and those decisions depend on your history. If you think a medication caused a serious problem, you or your clinician can also report it to the FDA through MedWatch.

What monitoring usually involves

Labels ask prescribers to check blood pressure and pulse before and during treatment and to reassess the risk of misuse throughout. The UK's NICE guideline NG87 recommends measuring adults' weight every 6 months and checking heart rate and blood pressure before and after each dose change and every 6 months. In New York and New Jersey, controlled-substance rules also shape how often prescriptions are renewed; see ADHD medication rules in New York and how often follow-up visits happen.

A short log helps: sleep, appetite, mood and any new symptom, with the date. It makes follow-up visits more useful and side effects easier to sort from coincidence. Dr. Shershow provides medication management when medication is appropriate, with follow-up by secure video; the adult ADHD treatment page explains how that works. For a list of things to raise before a first prescription, see questions to ask before starting ADHD medication.

Questions

What is the most common side effect of ADHD medication in adults?

For stimulants, decreased appetite, dry mouth and trouble sleeping lead the adult trial results in FDA labels. For atomoxetine and viloxazine, nausea, insomnia and fatigue are among the most common. Rates differ by drug and cannot be compared directly across trials.

Do side effects of ADHD medication go away?

Labels report side effects from short trials and do not say how long a given effect will last for a given person. Persistent or worsening side effects are a reason to talk with the prescriber, who may consider timing, formulation or a different medication.

When is a side effect an emergency?

Medication Guides say to go to the emergency room or get medical help right away for chest pain, shortness of breath, fainting, signs of serotonin syndrome, a painful or prolonged erection, or an overdose. Thoughts of suicide warrant a call or text to 988, or 911 if someone is in immediate danger.

Can nonstimulant ADHD medications cause serious side effects?

Yes. The Strattera label warns about rare severe liver injury, and both Strattera and Qelbree carry boxed warnings about suicidal thoughts. Qelbree's warning applies to adults: 1.6% of adults on the drug in its trial reported suicidal ideation, compared with none on placebo.

Should I stop my ADHD medication if I get side effects?

Talk with the prescriber before making any change, unless the Medication Guide directs emergency care. Many side effects can be addressed, and the right step depends on the symptom and your history. For emergency symptoms, follow the steps in the table above.

Sources

This article is general information, not medical or legal advice. Rules and coverage change; check the linked sources for the current position, and speak with a clinician or attorney about your own situation.

ADHD medication side effects in adults