What the label lists and what reports show
Guanfacine side effects
Guanfacine's FDA label: “Most common adverse reactions (≥5% and at least twice placebo rate) in fixed-dose monotherapy ADHD trials in children and adolescents (6 to 17 years): hypotension, somnolence, fatigue, nausea, and lethargy ( 6.1 ) Flexible dose-optimization ADHD trials in …” FAERS holds 7,825 reports naming it through July 30, 2026; the reaction reported most often, leaving out the conditions it is used for, product-use terms and outcomes, is somnolence (471 reports).
- Generic listed
- A presentation discontinued
Check it at the source: the guanfacine FDA label on DailyMed (effective June 23, 2025, Takeda Pharmaceuticals America, Inc.); the FDA FAERS public dashboard.
What does the patient leaflet say about side effects?
From the patient leaflet: What are the possible side effects of INTUNIV ?INTUNIV may cause serious side effects including: low blood pressure low heart rate fainting sleepiness increased blood pressure and heart rate after suddenly stopping INTUNIV (rebound hypertension). Suddenly stopping INTUNIV can cause increased blood pressure and heart rate and other withdrawal symptoms such as headache, confusion, nervousness, agitation, and tremors. If these symptoms continue to get worse and are left untreated, it could lead to a very serious condition including very high blood pressure, feeling very sleepy or tired, severe headache, vomiting, vision problems, seizures. Get medical help right away, if you have any of the symptoms listed above. […]
Source: FDA drug label, Takeda Pharmaceuticals America, Inc., effective June 23, 2025 (SPL set b972af81-3a37-40be-9fe1-3ddf59852528), via openFDA; the full label on DailyMed
What does the label list?
From the label: adverse reactionsMost common adverse reactions (≥5% and at least twice placebo rate) in fixed-dose monotherapy ADHD trials in children and adolescents (6 to 17 years): hypotension, somnolence, fatigue, nausea, and lethargy ( 6.1 ) Flexible dose-optimization ADHD trials in children (6 to 12 years) and adolescents (13 to 17 years): somnolence, hypotension, abdominal pain, insomnia, fatigue, dizziness, dry mouth, irritability, nausea, vomiting, and bradycardia ( 6.1 ).
Table 10: Other Common Adverse Reactions (≥2% for all doses of INTUNIV and >rate than in placebo) in the Monotherapy Flexible Dose Study 5
| Adverse Reaction Term | Placebo (N=155) | All Doses of INTUNIV (N=157) |
|---|---|---|
| Headache | 18% | 27% |
| Fatigue | 12% | 22% |
| Dizziness | 10% | 16% |
| Decreased Appetite | 14% | 15% |
| Abdominal Pain The abdominal pain term includes abdominal pain, abdominal pain lower,… | 8% | 12% |
| Irritability | 4% | 7% |
| Anxiety The anxiety term includes anxiety and nervousness. | 3% | 5% |
| Rash The rash term includes rash, rash generalized, and rash papular. | 1% | 3% |
| Constipation | 0% | 3% |
| Increased Weight | 2% | 3% |
| Abdominal/Stomach Discomfort The abdominal/stomach discomfort term includes abdominal… | 1% | 2% |
| Pruritus | 1% | 2% |
Rows and numbers as the label prints them, under its own column headings (the first rows of a longer table where it runs on). A reaction in a trial table is not necessarily caused by the medicine, and trials differ from everyday use.
From the label: adverse reactions, continuedThe following serious adverse reactions are described elsewhere in the labeling: Hypotension, bradycardia, and syncope [see Warnings and Precautions (5.1) ] Sedation and somnolence [see Warnings and Precautions (5.2) ] Cardiac conduction abnormalities [see Warnings and Precautions (5.3) ] Rebound Hypertension [see Warnings and Precautions (5.4) ] Most common adverse reactions (≥5% and at least twice placebo rate) in fixed-dose monotherapy ADHD trials in children and adolescents (6 to 17 years): hypotension, somnolence, fatigue, nausea, and lethargy ( 6.1 ) Flexible dose-optimization ADHD trials in children (6 to 12 years) and adolescents (13 to 17 years): somnolence, hypotension, abdominal pain, insomnia, fatigue, dizziness, dry mouth, irritability, nausea, vomiting, and bradycardia ( 6.1 ). Adjunctive treatment to psychostimulant ADHD trial in children and adolescents (6 to 17 years): somnolence, fatigue, insomnia, dizziness, and abdominal pain ( 6.1 ). To report SUSPECTED ADVERSE REACTIONS, contact Takeda Pharmaceuticals at 1-877-TAKEDA-7 (1-877-825-3327) or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. …
Source: FDA drug label, Takeda Pharmaceuticals America, Inc., effective June 23, 2025 (SPL set b972af81-3a37-40be-9fe1-3ddf59852528), via openFDA; the full label on DailyMed
What do FAERS reports show?
7,825 reports list guanfacine among the medicines taken, each a report of something that happened, not proof the medicine caused it; 245 are coded as a death and 1,909 as a hospital stay. Counts follow how widely a medicine is used and watched, and they are not a measure of how risky it is. Of the 18 reactions below, 12 are named by the same term (in US spelling) in the label's adverse reactions, warnings or patient leaflet; a reaction the label does not name may still be there under another word, and a report does not show that the medicine caused it.
Reports received each year
The 25 most reported reactions
Source: FDA Adverse Event Reporting System (FAERS) via openFDA, reports through July 30, 2026; reactions as MedDRA preferred terms
What next?
- Guanfacine: the full record
- label, generics, price, shortages, recalls
- Report a side effect to the FDA
- MedWatch
- Side effects hub
- the most reported medicines and reactions