What the label lists and what reports show
Pioglitazone side effects
Pioglitazone's FDA label: “Most common adverse reactions (≥5%) are upper respiratory tract infection, headache, sinusitis, myalgia, and pharyngitis.” FAERS holds 44,186 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 bladder cancer (8,754 reports).
- Generic listed
- Boxed warning
Check it at the source: the pioglitazone FDA label on DailyMed (effective March 28, 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 ACTOS?ACTOS may cause serious side effects including: • See "What is the most important information I should know about ACTOS?" • low blood sugar (hypoglycemia). This can happen if you skip meals, if you also use another medicine that lowers blood sugar, or if you have certain medical problems. Lightheadedness, dizziness, shakiness, or hunger may happen if your blood sugar is too low. Call your doctor if low blood sugar levels are a problem for you • liver problems. Call your doctor right away if you have: o nausea or vomiting o stomach pain o unusual or unexplained tiredness o loss of appetite o dark urine o yellowing of your skin or the whites of your eyes • bladder cancer. There may be an increased chance of having bladder cancer when you take ACTOS. You should not take ACTOS if you are receiving treatment for bladder cancer. […]
Source: FDA drug label, Takeda Pharmaceuticals America, Inc., effective March 28, 2025 (SPL set d2ddc491-88a9-4063-9150-443b4fa4330c), via openFDA; the full label on DailyMed
What does the label list?
From the label: adverse reactionsMost common adverse reactions (≥5%) are upper respiratory tract infection, headache, sinusitis, myalgia, and pharyngitis.
Table 5. PROactive Trial: Incidence and Types of Adverse Events Reported in >5% of…
| Reaction | Placebo N=2633 | ACTOS N=2605 |
|---|---|---|
| Hypoglycemia | 18.8 | 27.3 |
| Edema | 15.3 | 26.7 |
| Cardiac Failure | 6.1 | 8.1 |
| Pain in Extremity | 5.7 | 6.4 |
| Back Pain | 5.1 | 5.5 |
| Chest Pain | 5.0 | 5.1 |
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 discussed elsewhere in the labeling: • Congestive heart failure [see Boxed Warning and Warnings and Precautions (5.1) ] • Edema [see Warnings and Precautions (5.5) ] • Fractures [see Warnings and Precautions (5.6) ] Most common adverse reactions (≥5%) are upper respiratory tract infection, headache, sinusitis, myalgia, and pharyngitis. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Takeda Pharmaceuticals America, Inc. at 1-877-TAKEDA-7 (1-877-825-3327) or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. Over 8500 patients with type 2 diabetes have been treated with ACTOS in randomized, double-blind, controlled clinical trials, including 2605 patients with type 2 diabetes and macrovascular disease treated with ACTOS in the PROactive clinical trial. In these trials, over 6000 patients have been treated with ACTOS for six months or longer, over 4500 patients have been treated with ACTOS for one year or longer, and over 3000 patients have been treated with ACTOS for at least two years. …
Source: FDA drug label, Takeda Pharmaceuticals America, Inc., effective March 28, 2025 (SPL set d2ddc491-88a9-4063-9150-443b4fa4330c), via openFDA; the full label on DailyMed
What do FAERS reports show?
44,186 reports list pioglitazone among the medicines taken, each a report of something that happened, not proof the medicine caused it; 4,418 are coded as a death and 12,322 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. Reports rose sharply in 2016 (3,875, against a median of 1,157 a year): FAERS counts follow reporting, which news, litigation and label changes can drive, not how often a reaction happens. Of the 23 reactions below, 9 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?
- Pioglitazone: 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