As with other drugs, Actos (pioglitazone) can cause side effects, such as headache and weight gain. If side effects of Actos become difficult to tolerate, talk with your doctor or pharmacist.

Actos (pioglitazone) is a brand-name oral tablet that’s prescribed for type 2 diabetes, along with a healthy diet and exercise.

If you have problems with side effects from Actos, talk with your doctor or pharmacist. They can discuss ways to manage side effects or other available treatment options. Do not stop taking Actos without consulting your doctor first.

For additional information about Actos, including details about its uses, see this Actos overview article.

Actos has a boxed warning. A boxed warning is the most serious warning from the Food and Drug Administration (FDA). For details, see the “Boxed warning for Actos” section.

Actos can cause certain side effects, some of which are more common than others. These may occur when you first start taking the medication, but they should go away over time.

These are just a few of the more common side effects reported by people who took Actos in clinical studies:

If any of these side effects become bothersome or severe, talk with your doctor. They may be able to suggest treatments to help ease the side effects. Or, your doctor may recommend a medication other than Actos.

Mild side effects can occur with Actos use. This list doesn’t include all possible mild side effects of the drug. For more information, see the prescribing information for Actos.

Mild side effects of Actos can include:

  • headache
  • muscle pain
  • sinus infection
  • sore throat
  • upper respiratory infections, such as the common cold
  • weight gain (see the “Managing side effects” section)

These side effects usually go away with time. But if you have side effects that are bothersome or severe while taking Actos, talk with your doctor.

Note: After the Food and Drug Administration (FDA) approves a drug, it tracks and reviews side effects of the medication. Sharing your experience helps make medications safer for everyone by giving doctors and researchers more information about how the drug works in real life. If you develop a side effect while taking Actos and want to tell the FDA about it, visit MedWatch or call 800-FDA-1088.

Actos may cause serious side effects, but this isn’t common. The following list may not include all possible serious side effects of the drug. For more information, see the prescribing information for Actos.

If you develop serious side effects while taking Actos, call your doctor right away. If the side effects seem life threatening or you think you’re having a medical emergency, immediately call 911 or your local emergency number.

Serious side effects that have been reported include:

For more information about some of these side effects, see the “Managing side effects” and “Boxed warning for Actos” sections.

* Use of the term “female” in this article refers to a person’s sex assigned at birth.

Allergic reaction

For some people, Actos can cause an allergic reaction. But it’s not clear whether this side effect occurred in the drug’s studies.

In general, symptoms of allergic reaction can be mild or serious.

Ways to manage

For mild allergic reaction symptoms, such as a mild rash, call your doctor right away. They may recommend treatments to help manage your symptoms. They’ll also let you know whether you should keep taking the medication.

For severe allergic reaction symptoms, such as swelling or trouble breathing, call 911 or your local emergency number right away. These symptoms require immediate medical care because they can become life threatening. If you’ve had a serious allergic reaction to Actos, your doctor may recommend taking a different medication instead.

Actos has a boxed warning. A boxed warning is the most serious warning from the Food and Drug Administration (FDA).

Congestive heart failure

Actos may cause new congestive heart failure (CHF) or make the condition worse if you already have it.

With CHF, your heart isn’t able to pump blood as well as it should, which can lead to fluid buildup in your body. CHF symptoms can include trouble breathing and rapid and unexplained weight gain. Another possible symptom is swelling, particularly in your hands, legs, and feet.

Your doctor will monitor you for CHF symptoms during your Actos treatment and after any dosage increases. They may decrease your dosage or have you stop Actos treatment if you develop CHF while using it.

If you already have CHF with symptoms, you shouldn’t take Actos. For more information about Actos and heart failure, talk with your doctor.

While taking Actos, you may be able to take steps to make side effects easier to manage.

If you have problems with side effects that do not go away or become worse, talk with your doctor or pharmacist. They can discuss options for managing side effects or other available treatment options.

Weight gain

Weight gain is a possible side effect of Actos. This was commonly observed in clinical studies of the drug. Researchers noticed that the weight gain was related to the dose of Actos. People who took a higher dose of the drug gained more weight, on average, than people who took a lower dose.

Weight gain can be caused by edema (fluid buildup), which is another potential side effect of Actos. Weight gain may also be caused by an increase in body fat.

Sudden and unexplained weight gain may be a symptom of congestive heart failure or edema, both of which are potential serious side effects of Actos. For more information, see “Congestive heart failure” below.

Actos works to treat type 2 diabetes by helping your body move sugar out of your blood and into your muscles and fat. So, it makes sense that the drug can cause some weight gain.

What you can do

If you’re concerned about weight gain while taking Actos, talk with your doctor. They may suggest making dietary or exercise changes to help you manage your weight. If your weight gain is due to fluid buildup, your doctor may recommend a medication to help. Or, they may suggest a drug other than Actos.

If you notice sudden or unexplained weight gain, such as gaining 3 to 5 pounds (lb) over 24 hours, contact your doctor right away. This may be a symptom of congestive heart failure. To learn more about congestive heart failure and Actos, see “Congestive heart failure” below.

Edema

Edema refers to swelling caused by a buildup of excess fluid in the body. This was a common side effect seen in clinical studies of Actos.

Edema most commonly occurs in the hands and feet, particularly around the ankles. Other symptoms may include headache and sudden weight gain that’s unexpected or unexplained.

What you can do

It’s very important to keep an eye out for edema while taking Actos. If you notice any unusual or excessive swelling while taking the drug, call your doctor right away. It’s possible that edema could be caused by Actos. But edema could also be a sign of congestive heart failure, which is a serious potential side effect of Actos. (To learn more, see “Congestive heart failure” below.)

If you develop edema while taking Actos, your doctor will work to determine the cause and the best way to treat it. This may include trying a different medication to treat your diabetes.

Low blood sugar

Actos treats type 2 diabetes by lowering your blood sugar. But it’s possible for blood sugar to become too low. This is known as hypoglycemia. This was common in clinical trials of Actos.

Taken alone, Actos may cause low blood sugar, but this isn’t common. However, the risk is increased if you skip meals, drink a lot of alcohol, or exercise a lot. Your risk for low blood sugar will typically increase further if your Actos dose is raised or you also use other type 2 diabetes medications. Some examples of these medications include glipizide (Glucotrol) and insulin.

In addition, the risk may increase if you have other medical conditions, such as kidney disease, or you are taking a beta-blocker for heart failure.

Symptoms of low blood sugar can include:

  • an abnormally fast or slow heart rate
  • dizziness or lightheadedness
  • nausea and vomiting
  • tiredness or weakness
  • anxiousness or nervousness
  • headache
  • sweating

What you can do

If you have any symptoms of low blood sugar while using Actos, call your doctor. If your blood sugar level drops too low, it can become a medical emergency. Your doctor will work with you to find the right dosage of Actos to help you avoid low blood sugar. They may also prescribe a different medication for treating your type 2 diabetes.

Congestive heart failure

Actos has a boxed warning for congestive heart failure (CHF). This is the most serious warning from the Food and Drug Administration (FDA). The drug may cause new CHF or make the condition worse if you already have it.

Reports of CHF in clinical trials of Actos were rare. For more information, see the “Boxed warning for Actos” section.

CHF is a condition in which your heart doesn’t pump blood as well as it should. This can cause edema (fluid buildup in your body), especially in the hands, feet, and lower legs. Other symptoms of CHF may include trouble breathing, tiredness, and changes in heart rate.

What you can do

If you have any symptoms of CHF while taking Actos, talk with your doctor right away. CHF is a serious condition, and they’ll typically want to examine you to recommend a treatment plan.

Actos may cause several side effects. Here are answers to some frequently asked questions about the drug’s side effects.

What happens if I stop using Actos suddenly?

If you stop using Actos suddenly, your blood sugar level will likely begin to rise. Over time, this can cause health problems linked to type 2 diabetes. These include problems with the eyes, such as diabetic retinopathy, and problems with the kidneys, such as diabetic nephropathy.

For this reason, you shouldn’t stop taking Actos without first speaking with your doctor. They can help decide whether it’s safe for you to stop using the medication. Your doctor can also determine whether a different medication may help treat your condition.

Actos isn’t known to cause withdrawal symptoms. These are side effects that can develop if you stop using a drug that your body has become dependent on.

If you have other questions about ending your Actos treatment, talk with your doctor.

Do side effects vary depending on the Actos dosage I’m taking?

They may. Actos is available in three different strengths: 15 milligrams (mg), 30 mg, and 45 mg. The side effects are the same for all three strengths. But certain side effects seem to occur more often as the dose of Actos increases. These include low blood sugar, weight gain, edema, and flatulence.

If you have more questions about the side effects of Actos, or if you develop side effects while taking the drug, talk with your doctor.

Will taking Actos with food help prevent side effects?

No, it won’t. There aren’t any side effects from Actos that are known to be worsened or made better by taking the medication with or without a meal.

You can take Actos with or without food, unlike some other type 2 diabetes medications. Also, you don’t need to time your Actos doses with your meals in any way.

Keep in mind that if you have type 2 diabetes and skip meals, you may develop low blood sugar. This is also a potential side effect of Actos, so skipping meals may increase your risk for low blood sugar. For this reason, it’s important to stick to a regular eating schedule while taking Actos.

Drinking alcohol may also increase your risk for low blood sugar. Talk with your doctor about whether any amount of alcohol is safe for you to drink during your treatment. (For more information about low blood sugar, see the “Managing side effects” section.)

If you have other questions about how to take Actos, talk with your doctor.

Take note of the following important information to consider before taking Actos.

Actos has a boxed warning. A boxed warning is the most serious warning from the Food and Drug Administration (FDA). For details, see the “Boxed warning for Actos” section.

Other precautions

Before taking Actos, discuss your health history with your doctor. Actos may not be right for you if you have certain medical conditions or other factors affecting your health.

Be sure to talk with your doctor if any of the following apply to you:

Type 1 diabetes. If you have type 1 diabetes, you shouldn’t use Actos. The drug doesn’t work to treat this condition. Actos only works when your body is making normal amounts of insulin. Talk with your doctor about which other medications are right for you.

Diabetic ketoacidosis. You shouldn’t take Actos if you’re experiencing a serious condition known as diabetic ketoacidosis (DKA). This is because the drug doesn’t work to treat DKA. Actos works only when your body is making normal amounts of insulin. DKA is a medical emergency requiring urgent treatment. Talk with your doctor or local emergency medical provider if you experience symptoms such as fruity-smelling breath, deep, rapid breathing, headache, muscle aches, or all of these.

Liver problems. If you have liver disease, such as cirrhosis or hepatitis, Actos may worsen your condition. Before you start taking Actos, talk with your doctor about any history of liver problems you may have. They may monitor your liver during your treatment. If liver tests show abnormal results, your doctor will typically have you stop using Actos so they can determine the cause of the liver damage. Depending on the severity of your condition, they may cautiously restart your Actos treatment or recommend a different drug.

Osteoporosis. Actos may increase your risk for bone fractures. If you have osteoporosis and use Actos, your risk for breaking a bone may rise. Be sure to tell your doctor if you have osteoporosis before you take Actos. They may adjust your Actos dosage or recommend a different drug.

Bladder cancer. You shouldn’t take Actos if you’re receiving treatment for bladder cancer. Actos may increase your risk for developing bladder cancer. If you currently have bladder cancer or have had it in the past, be sure to tell your doctor before using Actos. They may monitor your bladder more than usual or recommend a drug other than Actos.

Allergic reaction. If you’ve had an allergic reaction to Actos or any of its ingredients, you shouldn’t take the drug. Ask your doctor about which other medications are better options for you.

Irregular periods. If you don’t have regular periods, taking Actos may increase the chance of becoming pregnant. This is because the drug may cause ovulation. If you have irregular periods, be sure to tell your doctor before you take Actos. They’ll work with you to determine whether the drug is safe and effective for you. If it isn’t, they’ll help find the best treatment for your condition.

Eye disease. If you have macular degeneration or diabetic macular edema, Actos may worsen your eye condition. Be sure to tell your doctor about past and current eye problems before you start Actos.

Alcohol use with Actos

Drinking alcohol may cause low blood sugar, which is also a possible side effect of Actos. For this reason, it may not be safe for you to consume alcohol while taking the medication.

Before you start taking Actos, talk with your doctor about how much, if any, alcohol is safe for you to drink.

Pregnancy and breastfeeding while taking Actos

It isn’t known if Actos is safe to use while pregnant or breastfeeding.

If you’re pregnant, planning to become pregnant, or considering breastfeeding, talk with your doctor before you start taking Actos. They’ll review the benefits and risks of this medication with you. Your doctor can also help you manage your type 2 diabetes during your pregnancy.

Disclaimer: Medical News Today has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or other healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.