Atomoxetine Side Effects

Medically reviewed by Drugs.com. Last updated on Jun 9, 2023.

Applies to atomoxetine: oral capsule.

Precautions

It is very important that your doctor check you or your child's progress at regular visits to make sure this medicine is working properly and to decide if you should continue to take it. Blood tests may be needed to check for unwanted effects.

This medicine may make you more drowsy, dizzy, less alert, or lightheaded than normal. Make sure you know how you react to this medicine before you drive, use machines, or do anything else that could be dangerous if you are dizzy or not alert. Dizziness, lightheadedness, or fainting may also occur when you get up suddenly from a lying or sitting position. Getting up slowly or lying down for awhile may help.

Do not take atomoxetine with or within 14 days of taking a drug with monoamine oxidase (MAO) inhibitor activity (eg, isocarboxazid [Marplan®], phenelzine [Nardil®], procarbazine [Matulane®], selegiline [Eldepryl®], or tranylcypromine [Parnate®]). If you do, you may develop serious side effects.

This medicine may cause serious allergic reactions, including anaphylaxis, angioneurotic edema, which can be life-threatening and require immediate medical attention. Call your doctor right away if you or your child have chest tightness, cough, difficulty swallowing, dizziness, fast heartbeat, hives, itching, skin rash, large, hive-like swelling on face, eyelids, lips, tongue, throat, hands, legs, feet, or sex organs, puffiness or swelling of the eyelids or around the eyes, face, lips or tongue, trouble breathing, or unusual tiredness or weakness after you take this medicine.

Check with your doctor right away if you have pain or tenderness in the upper stomach, pale stools, dark urine, loss of appetite, nausea, vomiting, or yellow eyes or skin. These could be symptoms of a serious liver problem.

Atomoxetine may cause serious heart or blood vessel problems. This may be more likely in patients who have a family history of heart disease. Check with your doctor right away if you or your child have chest pain, trouble breathing, or fainting while taking this medicine.

You will also need to have your blood pressure and heart rate measured before starting this medicine and while you are using it. If you notice any change in your blood pressure, call your doctor right away. If you have questions about this, talk to your doctor.

Dizziness, lightheadedness, or fainting may occur, especially when you get up suddenly from a lying or sitting position. These symptoms are more likely to occur when you begin taking this medicine or when the dose is increased. Getting up slowly or lying down for awhile may help.

Tell your doctor right away if you, your child, or a caregiver notices any unusual changes in behavior, such as an increase in aggression, hostility, agitation, irritability, or suicidal thinking or behavior. Also tell your doctor if you have hallucinations or any unusual thoughts, especially if they are new or getting worse quickly.

This medicine may cause slow growth in children. Your child's doctor will keep track of height and weight.

If you or your child experience a prolonged or painful erection of the penis for more than 4 hours, check with your doctor right away.

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.

Common side effects of atomoxetine

Some side effects of atomoxetine may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

Serious side effects of atomoxetine

Along with its needed effects, atomoxetine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking atomoxetine:

For healthcare professionals

Applies to atomoxetine: oral capsule.

Gastrointestinal adverse events

• Very common (10% or more): Dry mouth (up to 35%), nausea (up to 26%), abdominal pain/discomfort (up to 18%), constipation (up to 11%), vomiting (up to 11%)
• Common (1% to 10%): Dyspepsia, gastroenteritis, diarrhea, flatulence^[Ref]

Metabolic

• Very common (10% or more): Decreased appetite (up to 24%)
• Common (1% to 10%): Decreased weight, anorexia^[Ref]

Cardiovascular

• Very common (10% or more): Increased heart rate (up to 23.4%), increased blood pressure (up to 21.5%)
• Common (1% to 10%): Orthostatic hypotension, palpitations, flushing/hot flush, sinus tachycardia, tachycardia
• Uncommon (0.1% to 1%): QT interval prolongation
• Rare (less than 0.1%): Raynaud's phenomenon and/or peripheral vascular instability
• Frequency not reported: Myocardial infarction^[Ref]

Endocrine

• Very common (10% or more): Erectile dysfunction (up to 21%)
• Common (1% to 10%): Dysmenorrhea, delayed ejaculation/ejaculation disorder/ejaculation failure, sexual dysfunction, impotence, prostatitis, abnormal orgasm, irregular menstruation, testicular pain, male genital pain
• Postmarketing reports: Priapism, male pelvic pain^[Ref]

Nervous system

• Very common (10% or more): Headache (up to 19%), somnolence/sedation (up to 11%)
• Common (1% to 10%): Dizziness, tremor, syncope/syncope vasovagal, paraesthesia, feeling jittery, dysgeusia
• Uncommon (0.1% to 1%): Seizures, hypoesthesia
• Frequency not reported: Stroke^[Ref]

Psychiatric

• Very common (10% or more): Insomnia (up to 19%)
• Common (1% to 10%): Aggression/hostility, irritability, mood swings, depression/depressed mood, early morning awakening, abnormal dreams, decreased libido, sleep disorder, agitation, anxiety
• Uncommon (0.1% to 1%): Suicide-related behavior (suicide attempts, suicidal ideation), psychotic/manic symptoms (e.g., hallucinations, delusional thinking, mania), restlessness, emotional lability, generalized anxiety disorder
• Frequency not reported: Panic attacks, impulsivity, akathisia, hypomania
• Postmarketing reports: Tics, libido changes, sensory disturbances, completed suicide^[Ref]

Dermatologic

• Very common (10% or more): Hyperhidrosis (up to 15%)
• Common (1% to 10%): Rash, excoriation, dermatitis, pruritus
• Uncommon (0.1% to 1%): Urticaria^[Ref]

Other

• Very common (10% or more): Fatigue (up to 10%)
• Common (1% to 10%): Unexpected therapeutic response, chills, thirst, peripheral coldness/feeling cold, influenza, pyrexia, rigors, lethargy, asthenia, chest pain
• Frequency not reported: Delayed growth (height and weight), sudden death^[Ref]

Genitourinary

• Common (1% to 10%): Urinary retention, urinary hesitation/decreased urine flow, dysuria, pollakiuria
• Uncommon (0.1% to 1%): Micturition urgency, enuresis^[Ref]

Ocular

• Common (1% to 10%): Conjunctivitis, mydriasis, blurred vision^[Ref]

Respiratory

• Common (1% to 10%): Upper respiratory tract infection
• Uncommon (0.1% to 1%): Pharyngitis, dyspnea
• Frequency not reported: Pharyngolaryngeal pain, oropharyngeal pain^[Ref]

Hepatic

• Uncommon (0.1% to 1%): Increased blood bilirubin
• Rare (less than 0.1%): Liver failure, abnormal/increased liver function tests, jaundice, hepatitis, liver injury, acute hepatic failure^[Ref]

Hypersensitivity

• Uncommon (0.1% to 1%): Allergic reactions (anaphylactic reactions, angioneurotic edema, urticarial, rash)^[Ref]

Musculoskeletal

• Uncommon (0.1% to 1%): Muscle spasms
• Frequency not reported: Back pain
• Postmarketing reports: Rhabdomyolysis^[Ref]

See also:

Frequently asked questions

• Qelbree vs. Strattera: How do they compare?

Further information

Atomoxetine side effects can vary depending on the individual. Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Note: Medication side effects may be underreported. If you are experiencing side effects that are not listed, submit a report to the FDA by following this guide.

Medical Disclaimer