Pentasa (mesalamine) is a brand-name prescription medication. The Food and Drug Administration (FDA) has approved it to treat ulcerative colitis in adults.

If Pentasa works for your ulcerative colitis, your doctor will likely recommend that you take the drug long term.

Here are some fast facts about Pentasa:

  • Active ingredient: mesalamine
  • Drug class: aminosalicylate
  • Drug form: oral capsule
  • Drug strengths: 250 milligrams (mg), 500 mg

As with other drugs, Pentasa can cause side effects. Read on to learn about potential common, mild, and serious side effects. For a general overview of Pentasa, including details about its uses, see this article.

Pentasa can cause certain side effects, some of which are more common than others. These side effects may be temporary, lasting a few days to weeks. However, if the side effects last longer than that, bother you, or become severe, be sure to talk with your doctor or pharmacist.

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

* For more information about this side effect, see “Side effect specifics” below.

Mild side effects can occur when taking Pentasa. This list doesn’t include all possible mild side effects of the drug. For more information, you can refer to Pentasa’s prescribing information.

Mild side effects that have been reported with Pentasa include:

These side effects may be temporary, lasting a few days to weeks. However, if the side effects last longer than that, bother you, or become severe, be sure to talk with your doctor or pharmacist.

Note: After the Food and Drug Administration (FDA) approves a drug, it tracks side effects of the medication. If you develop a side effect while taking Pentasa and want to tell the FDA about it, visit MedWatch.

* For more information about this side effect, see “Side effect specifics” below.

Most side effects of Pentasa are mild. However, Pentasa may cause serious side effects. The list below may not include all possible serious side effects of the drug. For more information, you can refer to Pentasa’s prescribing information.

If you develop serious side effects while taking Pentasa, 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 and their symptoms include:

* For more information about this side effect, see “Side effect specifics” below.

Learn more about some of the side effects that Pentasa may cause. To find out how often side effects occurred in clinical trials, see the prescribing information for Pentasa.

Hair loss

Hair loss is a possible side effect of Pentasa. This side effect was not common and was rarely reported in clinical trials.

What you can do

If you notice hair loss from taking Pentasa, talk with your doctor. They may be able to recommend an over-the-counter medication, such as Rogaine (minoxidil), to treat your hair loss.

Joint pain

You may develop joint pain during treatment with Pentasa. Joint pain was not a common side effect that people taking Pentasa reported. However, it did occur in clinical trials of the drug.

What you can do

If you experience joint pain while taking Pentasa, tell your doctor. They can help determine what may be causing your joint pain to occur. In addition, they may be able to recommend ways to decrease this side effect, such as taking an over-the-counter pain medication such as Tylenol (acetaminophen).

Constipation

Constipation may occur while taking Pentasa. However, constipation was not a common side effect of Pentasa. In fact, diarrhea was a more commonly reported side effect of Pentasa.

What you can do

If you have constipation while taking Pentasa, talk with your doctor about the best ways to treat it. They may be able to recommend medications, such as MiraLAX (polyethylene glycol), to treat your constipation.

Kidney problems

It’s possible to develop kidney problems while taking Pentasa. Kidney problems were not commonly reported in people taking Pentasa. However, it’s possible that kidney problems from this medication may be serious.

You should watch for symptoms of kidney problems while you’re taking Pentasa and report them to your doctor right away if you develop any. Symptoms of kidney problems can include:

  • swelling of the legs or feet
  • shortness of breath
  • urinating more or less often than usual
  • nausea
  • vomiting

Pentasa may also increase your risk of developing kidney stones. Symptoms may include pain, blood in your urine, nausea, or fever.

What you can do

Before you start treatment with Pentasa, your doctor will check your kidneys with a blood test. Then, they will monitor your kidney function throughout your treatment with Pentasa to be sure that your kidneys are still working well.

You should tell your doctor right away if you develop symptoms of kidney problems. They can check your kidney function with blood tests.

In addition, be sure to tell your doctor if you have any kidney problems before starting Pentasa. If you already have kidney problems, taking Pentasa may worsen your condition. Your doctor can help determine if Pentasa may be a safe treatment option for you.

Allergic reaction

As with most drugs, Pentasa can cause an allergic reaction in some people. However, allergic reaction was not reported in clinical trials of Pentasa.

Symptoms can be mild or serious and can include:

  • skin rash
  • itching
  • flushing
  • swelling under your skin, typically in your eyelids, lips, hands, or feet
  • swelling of your mouth, tongue, or throat, which can make it hard to breathe

What you can do

For mild symptoms of an allergic reaction, call your doctor right away. They may recommend ways to ease your symptoms and determine whether you should keep taking Pentasa. However, if your symptoms are serious and you think you’re having a medical emergency, immediately call 911 or your local emergency number.

Pentasa may cause several side effects. Here are some frequently asked questions about the drug’s side effects and their answers.

Is weight gain a side effect of Pentasa?

No, weight gain wasn’t a side effect that people taking Pentasa reported. So, you shouldn’t experience weight gain from taking this medication.

However, Pentasa works to treat your ulcerative colitis (UC). This condition may cause you to lose weight. So, by treating UC, Pentasa may allow you to eat and digest food better, which can lead to weight gain.

In addition, certain medications used to treat ulcerative colitis, such as Rayos (prednisone), may lead to weight gain.

If you experience weight gain during treatment with Pentasa, talk with your doctor. They can help determine what may be causing your weight gain.

Does Pentasa cause anxiety?

No, you should not experience anxiety from taking Pentasa. This was not a side effect that people taking Pentasa reported in studies.

It’s possible that other medications used to treat ulcerative colitis may cause mood changes to occur. For example, the drug Rayos (prednisone) may cause mood changes, depression, personality changes, or other mood problems.

In addition, it’s possible to experience anxiety from your ulcerative colitis.

If you have anxiety during your treatment with Pentasa, talk with your doctor. They can help determine what may be causing your anxiety and the best way to treat it.

Be sure to talk with your doctor about your health history before you take Pentasa. This drug may not be the right treatment for you if you have certain medical conditions or other factors that affect your health. These are considered drug-condition or drug-factor interactions. The conditions and factors to consider include:

Kidney problems. Pentasa may cause kidney problems. If you already have kidney problems, taking Pentasa may worsen your condition. Your doctor will monitor your kidneys throughout your treatment with Pentasa. If your kidney condition worsens, your doctor may recommend a different treatment option for you.

Allergic reaction to salicylate drugs. If you’ve had an allergic reaction to Pentasa or any of its ingredients, including salicylate drugs, your doctor will likely not prescribe Pentasa. These drugs include aspirin, Colazal (balsalazide), and Azulfidine (sulfasalazine). Ask your doctor what other medications may be better options for you.

Liver failure. It’s possible for Pentasa to cause liver failure. If you have liver problems, taking Pentasa may worsen your condition. In this case, your doctor may monitor your liver with blood tests to be sure that your liver condition isn’t worsening. Sometimes, such as if your liver problems get worse, your doctor may recommend a different treatment option for you.

Skin conditions. If you have skin conditions, such as dermatitis or eczema, tell your doctor before starting Pentasa. Pentasa may increase your skin’s sensitivity to the sun, which can mean that you get sunburn easier than usual. If you also have a skin condition such as dermatitis or eczema, you may be at an increased risk of side effects. Due to these risks, your doctor may recommend that you use sunscreen or wear clothing to protect your skin from the sun while taking Pentasa.

Kidney stones. Pentasa may cause kidney stones. If you have a history of kidney stones, taking Pentasa may increase your risk of developing kidney stones. Your doctor can help determine if Pentasa is the best treatment option for you and ways to prevent kidney stones during treatment.

Alcohol with Pentasa

There’s no known interaction between drinking alcohol and Pentasa. However, it’s possible that alcohol may worsen Pentasa’s side effects. Both alcohol and Pentasa may cause headaches, nausea, and vomiting. So, the combination may increase your risk of these side effects.

In addition, alcohol may increase your risk of a flare up of ulcerative colitis symptoms.

Talk with your doctor to see if it’s safe for you to drink alcohol while taking Pentasa.

Pregnancy and breastfeeding while taking Pentasa

It is unknown if it’s safe to take Pentasa during pregnancy or while breastfeeding.

Currently, there aren’t enough studies to determine if Pentasa may affect a developing fetus. Animal studies do not show an increased risk of congenital anomalies (also known as birth defects) if the animal is exposed to mesalamine (the active drug in Pentasa) during pregnancy. However, it’s important to note that animal studies do not always indicate what may happen in humans.

It’s possible that mesalamine may pass into breast milk in small amounts. However, it is unknown what effects this may have on a breastfeeding child. However, it’s possible that children exposed to mesalamine from breast milk may experience diarrhea.

Your doctor can help determine if it is safe for you to take Pentasa during pregnancy or while breastfeeding.

Most commonly, you may experience mild side effects from taking Pentasa. But it’s also possible to have more serious side effects from this medication.

If you’d like to learn more about Pentasa, talk with your doctor or pharmacist. They can help answer any questions about the drug’s side effects.

Besides talking with your doctor, you can do some research on your own. These articles might help:

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 another 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.