If you have ulcerative colitis (UC), your doctor may recommend treatment with Asacol HD. It’s a prescription drug used to treat moderately active UC in adults.

UC is a kind of inflammatory bowel disease. It causes inflammation and small sores called ulcers in the lining of your colon and rectum.

With UC, there will be times when you have symptoms. This is known as active UC. Other times, you may have no symptoms of UC, which is referred to as remission. Asacol HD is prescribed to treat moderately active UC. To learn more, see “Is Asacol HD used for ulcerative colitis?” below.

Asacol HD basics

Asacol HD contains the active drug mesalamine. (An active drug is the ingredient that makes a medication work.) Mesalamine is also the generic for Asacol HD. It belongs to a group of drugs called aminosalicylates.

Asacol HD comes as delayed-release tablets that you swallow. Delayed-release tablets don’t release the medication into your body until it reaches your colon.

Keep reading to learn about Asacol HD, including its side effects, dosage, cost, and more.

Like most drugs, Asacol HD may cause mild or serious side effects. The lists below describe some of the more common side effects that Asacol HD may cause. These lists don’t include all possible side effects.

Keep in mind that side effects of a drug can depend on:

  • your age
  • other health conditions you have
  • other medications you take

Your doctor or pharmacist can tell you more about the potential side effects of Asacol HD. They can also suggest ways to help reduce side effects.

Mild side effects

Here’s a short list of some of the mild side effects that Asacol HD can cause. To learn about its other mild side effects, talk with your doctor or pharmacist, or read Asacol HD’s prescribing information.

Mild side effects of Asacol HD that have been reported include:

Mild side effects of many drugs may go away within a few days to a couple of weeks. But if they become bothersome, talk with your doctor or pharmacist.

Serious side effects

Serious side effects from Asacol HD can occur, but they aren’t common. If you have serious side effects from Asacol HD, call your doctor right away. But if you think you’re having a medical emergency, call 911 or your local emergency number.

Serious side effects of Asacol HD that have been reported include:

* For more information about this side effect, see the “Side effect focus” section below.

Learn more about some of the side effects Asacol HD may cause.

Mesalamine-induced acute intolerance syndrome

Asacol HD may cause mesalamine-induced acute intolerance syndrome. This is a reaction some people have to drugs that contain mesalamine, the active drug in Asacol HD. (An active drug is the ingredient that makes a medication work.)

It’s not known why this side effect occurs in some people. In studies of Asacol HD, it wasn’t common.

Symptoms of mesalamine-induced acute intolerance syndrome are similar to those of ulcerative colitis (UC), the condition Asacol HD is prescribed to treat. These can include:

What might help

If you have symptoms of mesalamine-induced acute intolerance syndrome, let your doctor know right away. These symptoms will likely go away once you stop taking Asacol HD.

You and your doctor may decide that it’s best for you to stop taking Asacol HD. If so, they can recommend other treatment options for your UC symptoms.

Kidney problems

Treatment with Asacol HD may cause kidney problems. Kidney-related side effects weren’t reported in studies of Asacol HD. But they have happened since the drug became available for use.

Kidney problems reported in people taking Asacol HD or other drugs that contain mesalamine include:

Symptoms of kidney problems can vary, but some general ones include:

Symptoms of kidney stones may include:

  • bloody urine
  • nausea and vomiting
  • severe pain in your back or side

People who already have kidney problems, such as chronic kidney disease, may have a higher risk of kidney-related side effects from taking Asacol HD. You may also be at higher risk if you take other medications that can cause kidney problems.

What might help

Before you begin treatment with Asacol HD, your doctor will review your medical history. This helps them determine your risk of kidney problems if they prescribe Asacol HD. They’ll also monitor your kidney function while you’re taking Asacol HD.

If you notice symptoms of kidney problems while taking Asacol HD, contact your doctor right away. They can determine how to best manage your side effects. This may include stopping treatment with Asacol HD and trying a different medication for your UC symptoms.

To help prevent kidney stones while taking Asacol HD, be sure to drink plenty of fluids. Your doctor can tell you more about getting enough fluids while you’re taking Asacol HD.

Allergic reaction

Some people may have an allergic reaction to Asacol HD.

Symptoms of a mild allergic reaction can include:

A more severe allergic reaction is rare but possible. Symptoms of a severe allergic reaction can include swelling under your skin, usually in your eyelids, lips, hands, or feet. They can also include swelling of your tongue, mouth, or throat, which can cause trouble breathing.

Call your doctor right away if you have an allergic reaction to Asacol HD. But if you think you’re having a medical emergency, call 911 or your local emergency number.

Your doctor will recommend the dosage of Asacol HD that’s right for you. Below are commonly used dosages, but always take the dosage your doctor prescribes.

Form and strength

Asacol HD comes as delayed-release tablets that you swallow. Asacol HD tablets are specially made to make sure the medication isn’t released into your body until it reaches your colon. To learn more, see “Is Asacol HD used for ulcerative colitis?” below.

Asacol HD tablets come in one strength: 800 mg.

Recommended dosage

You’ll likely take Asacol HD three times each day for 6 weeks.

Questions about Asacol HD’s dosage

Below are a few questions and answers about Asacol HD’s dosage.

  • What if I miss a dose of Asacol HD? If you miss a dose of Asacol HD, try to take it as soon as you remember. But if it’s almost time for your next dose, skip the missed dose. Take your next dose at the regularly scheduled time. And do not double-up doses to make up for the missed dose. This may raise your risk of side effects.
  • Will I need to take Asacol HD long term? It’s not known whether Asacol HD is safe and effective when taken for more than 6 weeks. Your doctor can tell you more about how long you’ll take this drug.
  • How long does Asacol HD take to work? Asacol HD begins working as soon as you take a dose. But it may take a few weeks before you notice your symptoms decreasing.

Find answers to some commonly asked questions about Asacol HD.

Is Asacol HD taken in doses of 400 mg, 500 mg, 1,200 mg, or 1,600 mg?

The only recommended dose of Asacol HD is 1,600 milligrams (mg) taken three times per day. Asacol HD tablets only come in a strength of 800 mg. This means you’ll need to take two tablets for each 1,600-mg dose, for a total of six tablets per day.

For more information on Asacol HD’s dosage, see the “What is Asacol HD’s dosage?” section just above. You can also talk with your doctor or pharmacist to learn more dosage details for this drug.

Does Asacol HD treat Crohn’s disease?

Asacol HD isn’t approved by the Food and Drug Administration (FDA) to treat Crohn’s disease. But the drug may be used off-label for this purpose. Off-label drug use is when an FDA-approved drug is prescribed for a purpose other than what it’s approved for.

Note that the American College of Gastroenterology doesn’t recommend taking oral mesalamine to treat active Crohn’s disease. Oral means to take by mouth, and active means you’re experiencing symptoms of the disease. Mesalamine is the active drug in Asacol HD. An active drug is the ingredient that makes a medication work.

If you have questions about treatments for Crohn’s disease, talk with your doctor or pharmacist.

How does Asacol HD work?

How a drug works to treat a condition is called its mechanism of action.

Asacol HD’s mechanism of action for treating ulcerative colitis (UC) isn’t exactly known. But it’s believed to reduce inflammation (swelling and damage) in the colon and rectum.

Asacol HD tablets are specially formulated so that the medication isn’t released into your body until the tablet reaches your colon. This helps make sure the drug gets to where its anti-inflammatory actions are most needed to treat UC.

For more information on Asacol HD and treating UC, see the “Is Asacol HD used for ulcerative colitis?” section below. You can also talk with your doctor or pharmacist to learn more.

Costs of prescription drugs can vary depending on many factors. These factors include what your insurance plan covers and which pharmacy you use.

Asacol HD is available as the generic drug mesalamine. Generics usually cost less than brand-name drugs. See this article for information about mesalamine and cost. And talk with your doctor or pharmacist if you’d like to know more about taking generic mesalamine.

Financial assistance to help you pay for Asacol HD may be available. Medicine Assistance Tool and NeedyMeds are two websites that provide resources to help reduce the cost of Asacol HD.

You can also check out this article to learn more about saving money on prescriptions.

Asacol HD, Lialda, and Apriso all contain mesalamine as their active drug. (An active drug is the ingredient that makes a medication work.) They’re all used to treat ulcerative colitis (UC).

But they have some differences in how they’re used to treat UC. They also differ in their dosages. For example, you would usually take Apriso or Lialda once per day. But you would take Asacol HD doses three times per day.

To find out more about these three medications, see this detailed comparison. Also, check with your doctor about which drug is right for your condition.

Asacol HD is used to treat moderately active ulcerative colitis (UC) in adults. UC is a kind of inflammatory bowel disease. It causes inflammation (swelling and damage) and small sores called ulcers in the lining of your colon and rectum.

With UC, there will be times when you have symptoms. This is known as active UC. Other times, you may have no symptoms of UC, which is referred to as remission. Asacol HD is prescribed to treat moderately active UC.

Symptoms of UC can include:

Asacol HD’s mechanism of action for treating UC isn’t exactly known. But it’s believed to reduce inflammation (swelling and damage) in the colon and rectum.

Asacol HD tablets are specially formulated so that the medication isn’t released into your body until the tablet reaches your colon. This helps make sure the drug gets to where its anti-inflammatory actions are most needed to treat UC.

It’s not known whether Asacol HD is safe and effective when taken for more than 6 weeks. Your doctor can tell you more about how long you’ll take Asacol HD.

Your doctor will explain how you should take Asacol HD. They will also explain how much to take and how often. Be sure to follow your doctor’s instructions.

Taking Asacol HD

Asacol HD comes as tablets that you swallow. You’ll likely take a dose (two tablets) three times per day.

Accessible medication containers and labels

If it’s hard for you to read the label on your prescription, tell your doctor or pharmacist. Certain pharmacies may provide medication labels that:

  • have large print
  • use braille
  • contain a code you can scan with a smartphone to change the text into audio

Your doctor or pharmacist may be able to recommend a pharmacy that offers these options if your current pharmacy doesn’t.

Also, if you’re having trouble opening your medication bottles, let your pharmacist know. They may be able to put Asacol HD in an easy-open container. Your pharmacist may also recommend tools to help make it simpler to open the drug’s container.

Questions about taking Asacol HD

Here are answers to questions you might have about taking Asacol HD.

  • Can Asacol HD be chewed, crushed, or split? No, you should not chew, crush, or split Asacol HD tablets. They’re meant to be taken whole. If you’re having trouble swallowing pills, see this article for a few tips to try. Or talk with your doctor or pharmacist. They may be able to suggest a treatment that’s easier for you to take.
  • Should I take Asacol HD with food? No, because you need to take the drug on an empty stomach. Specifically, you should take your Asacol HD dose at least 1 hour before or 2 hours after a meal.
Questions for your doctor

You may have questions about Asacol HD and your treatment plan. It’s important to discuss all your concerns with your doctor.

Here are a few tips that might help guide your discussion:

  • Before your appointment, write down questions such as:
    • How will Asacol HD affect my body, mood, or lifestyle?
  • Bring someone with you to your appointment if doing so will help you feel more comfortable.
  • If you don’t understand something related to your condition or treatment, ask your doctor to explain it to you.

Remember, your doctor and other healthcare professionals are available to help you. And they want you to get the best care possible. So don’t be afraid to ask questions or offer feedback on your treatment.

Before you start taking Asacol HD, it’s important to tell your doctor about any medical conditions you have. You should also tell them about any medications you take. This helps them determine whether Asacol HD is the right treatment option for you.

Interactions

Taking a medication with certain vaccines, foods, and other things can affect how the medication works. These effects are called interactions.

Before taking Asacol HD, be sure to tell your doctor about all medications you take, including prescription and over-the-counter drugs. Also, describe any vitamins, herbs, or supplements you use. Your doctor or pharmacist can tell you about any interactions these items may cause with Asacol HD.

Interactions with drugs or supplements

Asacol HD can interact with several kinds of drugs. These drugs include:

This list does not contain all kinds of drugs that may interact with Asacol HD. Your doctor or pharmacist can tell you more about these interactions and any others that may occur with Asacol HD.

Other interactions

Asacol HD can interfere with certain lab tests that measure the normetanephrine level in your urine.

Normetanephrine is a substance produced by the breakdown of the hormone norepinephrine. If your doctor wants to check you for certain rare cancers, they may order a urine test for this substance.

Asacol HD can cause a false positive on this test. This means the test results may show a high normetanephrine level, even if your level is actually in the standard range.

If you need to have a normetanephrine urine test, let your doctor or other healthcare professional know that you’re taking Asacol HD.

Warnings

Asacol HD may not be right for you if you have certain medical conditions or other factors that affect your health. Talk with your doctor about your health history before you take Asacol HD. Factors to consider include those in the list below.

  • Kidney problems. Asacol HD can cause kidney problems as a side effect. If you already have kidney problems, such as chronic kidney disease, taking Asacol HD may worsen your condition. Your doctor can determine whether Asacol HD is safe for you to take.
  • Liver problems. In some cases, people with liver problems who took Asacol HD had liver failure. Before you take this drug, tell your doctor if you have liver problems. Your doctor can determine whether the medication is safe for you to take.
  • Skin conditions. People with certain skin conditions may find their skin reacts more severely than usual to sunlight while taking Asacol HD. Examples of such skin conditions include dermatitis or eczema. You can help protect your skin by using broad-spectrum sunblock and wearing clothing that covers your skin when you’re in the sun. If your doctor decides Asacol HD is safe for you to take, ask them about other ways to keep your skin safe from sunlight during treatment.
  • Iron overload. Asacol HD tablets have a coating that contains iron. If you’re at risk of iron overload, these tablets may not be safe for you to take. You may have a risk of iron overload if you take iron supplements or have frequent blood transfusions. In such cases, your doctor can determine whether Asacol HD is safe for you to take.
  • Allergic reaction. If you’ve had an allergic reaction to Asacol HD or any of its ingredients, your doctor will likely not prescribe Asacol HD. Ask your doctor what other medications are better options for you.

Asacol HD and alcohol

There’s no known direct interaction between alcohol and Asacol HD.

But alcohol could worsen certain side effects Asacol HD may cause, such as headache or nausea. And alcohol can trigger UC symptoms in some people, including diarrhea and bloating.

Talk with your doctor about how much alcohol is safe for you to consume while you’re taking Asacol HD.

Pregnancy and breastfeeding

It’s not known whether it’s safe to take Asacol HD while pregnant or breastfeeding.

If you’re pregnant or breastfeeding, or planning to become pregnant or breastfeed, tell your doctor before you begin taking Asacol HD. They can discuss safe treatment options for your condition.

Do not take more Asacol HD than your doctor prescribes. Taking more than this can lead to serious side effects.

Symptoms of overdose

Symptoms caused by an overdose can include:

What to do in case you take too much Asacol HD

Call your doctor if you think you’ve taken too much Asacol HD. You can also call 800-222-1222 to reach the American Association of Poison Control Centers, or use its online resource. But if you have severe symptoms, immediately call 911 or your local emergency number. Or go to the nearest emergency room.

If you’re considering treatment with Asacol HD, talk with your doctor or pharmacist. Ask questions that help you feel comfortable about the drug’s risks and benefits. Here are some examples to help you get started:

  • What should I know about alternative treatment options for my condition?
  • If I experience side effects from Asacol HD, are there different dosages I can try?
  • Will Asacol HD cause sexual side effects?
  • How will I know if Asacol HD is working for me?

You can learn more about treatment options for ulcerative colitis (UC) by checking out these articles:

You might also consider joining an online support group for people who have an inflammatory bowel disease (IBD), such as UC. If this interests you, check out the Bezzy IBD community.

For tips on managing UC, sign up for Healthline’s IBD newsletter.

Q:

Is it safe for older adults to take Asacol HD?

Anonymous

A:

Reports suggest certain side effects occur more often in adults ages 65 years and older who take mesalamine. This is the active drug in Asacol HD. (An active drug is the ingredient that makes a medication work.)

These side effects include certain blood disorders, such as neutropenia (low levels of neutrophils, a kind of white blood cell) and pancytopenia (low levels of red blood cells, white blood cells, and platelets).

Also, heart, liver, and kidney problems occur more often in older people. These are conditions that can raise your risk of side effects from Asacol HD.

Note that studies of Asacol HD did not include enough older people to determine the drug’s effect in people of this age group.

Before you start treatment with Asacol HD, your doctor will review your medical history. This will help determine your risk of certain side effects from Asacol HD. During treatment, they’ll also monitor your blood cell counts to check for any irregularities.

If you have any concerns about taking Asacol HD, talk with your doctor.

Tanya Kertsman, PharmDAnswers represent the opinions of our medical experts. All content is strictly informational and should not be considered medical advice.

Disclaimer: Healthline 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.

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