What the label lists and what reports show
Clonidine side effects
Clonidine's FDA label lists its adverse reactions in its own words. FAERS holds 57,116 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 fatigue (3,518 reports).
- Generic listed
Check it at the source: the clonidine FDA label on DailyMed (effective March 30, 2026, Unichem Pharmaceuticals (USA), Inc.); the FDA FAERS public dashboard.
What does the patient leaflet say about side effects?
From the patient leaflet: What are possible side effects of clonidine hydrochloride extended-release tablets?Clonidine hydrochloride extended-release tablets may cause serious side effects, including: Low blood pressure and low heart rate. Your doctor should check your heart rate and blood pressure before starting treatment and regularly during treatment with clonidine hydrochloride extended-release tablets. Sleepiness. Withdrawal symptoms. Suddenly stopping clonidine hydrochloride extended-release tablets may cause withdrawal symptoms including: increased blood pressure, headache, increased heart rate, lightheadedness, tightness in your chest and nervousness. The most common side effects of clonidine hydrochloride extended-release tablets include: sleepiness tiredness irritability trouble sleeping (insomnia) nightmare constipation dry mouth decreased appetite dizziness Tell your doctor if you have any side effects that bother you or that does not go away. […]
Source: FDA drug label (Clonidine hydrochloride), Ajanta Pharma USA Inc., effective October 31, 2025 (SPL set df80255e-f942-4d9f-8edd-cc95795772cb), via openFDA; the full label on DailyMed
What does the label list?
From the label: adverse reactionsMost adverse effects are mild and tend to diminish with continued therapy. The most frequent (which appear to be dose-related) are dry mouth, occurring in about 40 of 100 patients; drowsiness, about 33 in 100; dizziness, about 16 in 100; constipation and sedation, each about 10 in 100. The following less frequent adverse experiences have also been reported in patients receiving clonidine hydrochloride tablets, but in many cases patients were receiving concomitant medication and a causal relationship has not been established. Body as a Whole: Fatigue, fever, headache, pallor, weakness, and withdrawal syndrome. Also reported were a weakly positive Coombs' test and increased sensitivity to alcohol. …
Incidence of Adverse Events in the Two-Week Trial
This table is printed in the Duraclon label published by Mylan Institutional LLC of March 17, 2021; the label quoted above does not print one.
| Adverse Events | Clonidine N = 38 n (%) | Placebo N = 47 n (%) |
|---|---|---|
| Total Number of Patients Who Experienced at Least One Adverse Event | 37 (97.4) | 38 (80.5) |
| Hypotension | 17 (44.8) | 5 (10.6) |
| Postural Hypotension | 12 (31.6) | 0 (0) |
| Dry Mouth | 5 (13.2) | 4 (8.5) |
| Nausea | 5 (13.2) | 10 (21.3) |
| Somnolence | 5 (13.2) | 10 (21.3) |
| Dizziness | 5 (13.2) | 2 (4.3) |
| Confusion | 5 (13.2) | 5 (10.6) |
| Vomiting | 4 (10.5) | 7 (14.9) |
| Nausea/Vomiting | 3 (7.9) | 1 (2.1) |
| Sweating | 2 (5.3) | 0 (0) |
| Chest Pain | 2 (5.3) | 0 (0) |
| Hallucination | 2 (5.3) | 1 (2.1) |
| Tinnitus | 2 (5.3) | 0 (0) |
| Constipation | 1 (2.6) | 2 (4.3) |
| Tachycardia | 1 (2.6) | 2 (4.3) |
| Hypoventilation | 1 (2.6) | 2 (4.3) |
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.
Source: FDA drug label, Unichem Pharmaceuticals (USA), Inc., effective March 30, 2026 (SPL set 21bfa28f-20df-43fd-bb80-b720d3b40696), via openFDA; the full label on DailyMed
What do FAERS reports show?
57,116 reports list clonidine among the medicines taken, each a report of something that happened, not proof the medicine caused it; 6,861 are coded as a death and 19,924 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 20 reactions below, 8 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?
- Clonidine: 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