OpenClaim

Guanfacine Side Effects

The most commonly reported side effects of guanfacine include off label use, somnolence, and aggression, based on 9,023 FDA adverse event reports from 2004 to 2025. 10.0% of reports found the drug to be ineffective.

Guanfacine side effects

Percentages show how often each reaction appears relative to total reports for guanfacine.

1
Drug Ineffective10.0%906
2
Off Label Use7.2%648
3
Somnolence5.5%498
4
Aggression5.2%465
5
Fatigue4.1%371
6
Product Substitution Issue3.5%314
7
Insomnia3.4%310
8
Headache3.4%309
9
Anxiety3.2%292
10
Dizziness3.2%291
11
Hypotension3.2%286
12
Nausea3.1%280
13
Suicidal Ideation3.0%270
14
Abnormal Behaviour2.9%263
15
Bradycardia2.7%241

These are voluntary reports and do not establish that guanfacine caused these reactions.

Report severity

57.8%Serious5,215 reports
23.0%Hospitalizations2,079 reports
3.2%Fatal293 reports

Seriousness is determined by the reporter, not by OpenClaim.

Guanfacine drug interactions

Other drugs that appear in adverse event reports alongside guanfacine. Drugs flagged as a suspected cause appear in the first column. Drugs taken at the same time but not suspected appear in the second.

Also suspected

1
Methylphenidate10.8%971
2
Aripiprazole5.1%459
3
Lisdexamfetamine-dimesylate4.7%420
4
Risperidone4.5%407
5
Sodium-oxybate2.8%250
6
Atomoxetine-hydrochloride2.6%232
7
Quetiapine-fumarate2.4%214
8
Dupilumab2.2%197
9
Sertraline-hydrochloride2.1%185
10
Lamotrigine2.0%180
11
Dextroamphetamine1.9%169
12
Somatropin1.8%165
13
Olanzapine1.6%143
14
Amphetamine1.6%143
15
Clonidine1.4%129

Taken alongside

1
Methylphenidate8.8%792
2
Ergocalciferol6.6%599
3
Albuterol6.1%550
4
Sertraline-hydrochloride5.8%527
5
Acetaminophen5.4%488
6
Fluticasone5.3%475
7
Clonidine4.7%421
8
Risperidone4.7%420
9
Aripiprazole4.4%399
10
Fluoxetine-hydrochloride4.3%386
11
Cetirizine-hydrochloride4.3%386
12
Dextroamphetamine4.1%366
13
Amphetamine4.0%362
14
Gabapentin3.9%355
15
Omeprazole3.8%347

Co-occurrence in adverse event reports does not establish a drug interaction. Patients often take multiple medications, and these lists reflect prescribing patterns rather than causal relationships. Consult a healthcare provider about potential drug interactions.

Who reports guanfacine side effects

31.2% of guanfacine adverse event reports involve female patients and 52.2% involve male patients. The largest age group is child at 38%. These figures reflect who reports side effects, not underlying risk.

Sex

Female31.2%
Male52.2%
Unknown16.6%

Age group

< 20.4%
2–1137.6%
12–1726.9%
18–6429.2%
65+5.9%

What is guanfacine used for

Conditions and purposes for which patients were taking guanfacine when the adverse event was reported.

Abnormal BehaviourAccidental Exposure To Product By ChildAccidental OverdoseAdcy5-related DyskinesiaAdhdAdjustment DisorderAdjuvant TherapyAffect LabilityAffective DisorderAggressionAggressive BehaviourAgitationAmnesiaAngerAnxiety

Showing 15 of 288 indications

Guanfacine brand names and reporting trend

Guanfacine is sold under the brand name Intuniv.

Brand names

Intuniv7

Quarterly reports (20042025)

20052010201520202025

An upward trend reflects increased FAERS reporting overall, not necessarily increased risk.

Taking guanfacine with another medication?

Ask OpenClaim about your specific drug combination. Get a sourced report using FDA data, drug labels, and medical literature.