Drug side effects
guanfacine Side Effects
The reactions most often reported to the FDA for guanfacine (also sold as Intuniv, Tenex), with demographics, serious outcomes, and reporting trends.
Data updated 2026-05-15
- 7,386
- FAERS reports
Data from the FDA Adverse Event Reporting System (FAERS), 2004 to 2025. A FAERS report records a temporal association, not proof of cause. See our methodology for how figures are compiled and de-duplicated.
The most commonly reported side effects of guanfacine come from 7,386 reports to the FDA, broken down here by frequency, patient demographics, and serious outcomes.
This page analyzes 7,386 reports to the FDA Adverse Event Reporting System (FAERS) for guanfacine (Intuniv): the reactions reported most often, who reported them, serious outcomes such as hospitalization, and year-over-year trends. A FAERS report does not prove the drug caused the effect, and report volume tracks how widely a drug is used, not how likely an effect is for any one person. Educational information, not medical advice.
Total Reports
7,386
Reports Mentioning Death
228
3.1% of reports — not proof the medicine caused the death
Hospitalizations
1,757
23.8% of reports
Top Indication
Attention Deficit/Hyperactivity Disorder
Most Reported Adverse Reactions
Who Reports Side Effects
Gender Distribution
Age Distribution
Reporting Trend by Year
Reactions in Death Reports
Top reactions reported in 228 reports where death was an outcome. These are voluntarily reported and do not establish causation.
| Reaction | Reports |
|---|---|
| COMPLETED SUICIDE | 68 |
| DEATH | 51 |
| TOXICITY TO VARIOUS AGENTS | 31 |
| HYPOTENSION | 16 |
| COMA | 13 |
| GASTROINTESTINAL HAEMORRHAGE | 13 |
| TACHYCARDIA | 13 |
| RESPIRATORY DEPRESSION | 12 |
| DEPRESSED LEVEL OF CONSCIOUSNESS | 11 |
| ELECTROCARDIOGRAM QT PROLONGED | 11 |
| AGITATION | 10 |
| CARDIAC ARREST | 10 |
| DELIRIUM | 10 |
| DRUG INTERACTION | 10 |
| ELECTROCARDIOGRAM QRS COMPLEX PROLONGED | 10 |
| OVERDOSE | 10 |
| PARAESTHESIA | 10 |
| SUSPECTED SUICIDE | 10 |
| ASTHENIA | 9 |
Reactions in Hospitalization Reports
Top reactions in 1,757 reports where hospitalization was an outcome.
| Reaction | Reports |
|---|---|
| INTENTIONAL OVERDOSE | 181 |
| BRADYCARDIA | 175 |
| TOXICITY TO VARIOUS AGENTS | 169 |
| HYPOTENSION | 164 |
| SOMNOLENCE | 123 |
| OVERDOSE | 106 |
| DRUG INTERACTION | 99 |
| VOMITING | 92 |
| SUICIDE ATTEMPT | 89 |
| AGGRESSION | 84 |
| AGITATION | 83 |
| DIZZINESS | 78 |
| NAUSEA | 73 |
| ELECTROCARDIOGRAM QT PROLONGED | 72 |
| HYPERTENSION | 72 |
| SINUS BRADYCARDIA | 64 |
| CONDITION AGGRAVATED | 62 |
| HEADACHE | 62 |
Nearby, Related Medications
What the FAERS Data Reveals About guanfacine Side Effects
The FDA Adverse Event Reporting System (FAERS) contains 7,386 voluntary reports linked to guanfacine and its brand equivalents (Intuniv, Tenex), spanning 2004 through 2025. Of those, 228 (3.1%) listed death as an outcome and 1,757 (23.8%) involved hospitalization. The most common indication reported alongside adverse events was Attention Deficit/Hyperactivity Disorder.
Demographic breakdowns help contextualize who is being exposed to the drug. Of reports with known sex, 36% were female and 62% male; age distribution skews toward 0-17, with 3,034 reports in that bracket. The single most reported reaction is somnolence with 455 submissions, followed by aggression and fatigue.
How to read these numbers
FAERS is a signal-detection tool, not a scorecard. Reports are voluntary, and a single case may list multiple suspect drugs, so numbers above should not be read as incidence rates or per-patient risk. Widely prescribed drugs naturally accumulate more reports than niche therapies even when individual risk is low. These aggregates are useful for spotting patterns that merit further pharmacovigilance, not for choosing between medications. This page is for educational reference only and is not medical advice, speak with a licensed clinician about any side-effect concerns.
Drugs With a Similar FAERS Report Volume
Other medications with a total FDA adverse-event report count closest to guanfacine's 7,386.
Read our methodology - how this data is sourced, computed, and verified.