Asacol HD (mesalamine)

Medically Reviewed By Brittany A. Duke, PharmD, RPh

About Asacol HD

Asacol HD is a brand-name prescription drug. It’s approved by the Food and Drug Administration (FDA) to treat ulcerative colitis (UC) in adults.

With UC, you have inflammation in the large intestine. Doctors can prescribe Asacol HD for short-term treatment of UC that’s causing moderate to severe symptoms. Examples of these symptoms include rectal pain, abdominal pain, and nausea.

Asacol HD has a limitation for its use. For details about this and UC, see the “Asacol HD: Uses” section below.

Key points

The following table provides key facts about Asacol HD.

Active drug mesalamine
Drug class aminosalicylate, which is a type of anti-inflammatory drug
Form delayed-release (DR)* oral tablet

* DR means that the drug’s release is delayed until the tablet reaches your large intestine. To learn more, see the “Asacol HD: How it works” section below.

Finding a healthcare professional

If you’re interested in taking this drug, search here to find a doctor who might prescribe it.

Asacol HD: Generic

Asacol HD is a brand-name medication. It contains the active drug mesalamine, which also comes in a generic form. A generic is an identical copy of the active drug found in a brand-name medication.

The Food and Drug Administration (FDA) ensures that generic drugs are as safe and effective as their original drug. Generics tend to be less expensive than brand-name drugs.

If you’d like to know about taking the generic version of Asacol HD, ask your doctor or pharmacist. They can tell you if the generic medication comes in forms and strengths recommended for your condition.

Asacol HD: Dosage

Below, you’ll find dosages that are commonly recommended for Asacol HD. However, you should take the dosage your doctor prescribes for you. They’ll recommend the dosage that’s best for your needs.

Asacol HD’s forms and strengths

Asacol HD is available as follows.

  • Form: delayed-release (DR)* oral tablet
  • Strength: 800 milligrams (mg)

* DR means that the drug’s release is delayed until the tablet reaches your large intestine. To learn more, see the “Asacol HD: How it works” section below.

Asacol HD’s recommended dosage

Asacol HD is approved to treat ulcerative colitis (UC) in adults.

Asacol HD’s recommended dosage for UC is as follows.

  • Dose: 1,600 mg (two 800-mg tablets)
  • Frequency: three times per day

Dosage considerations

Below are some things to consider about Asacol HD’s dosage.

  • Missing a dose. If you miss a dose of Asacol HD, talk with your doctor or pharmacist. They’ll recommend whether you should take the missed dose or skip it. Try these tips to help avoid missing doses. You could also set an alarm, use a timer, or download a reminder app on your phone.
  • Length of treatment. Doctors typically don’t prescribe Asacol HD as a long-term treatment. Instead, they usually prescribe it for up to 6 weeks to treat moderate to severe symptoms of ulcerative colitis. Your doctor will determine how long you’ll take Asacol HD.

Asacol HD: Side effects

As with most drugs, it’s possible to have side effects with Asacol HD. These can include some mild side effects, but also some serious ones.

To learn more about Asacol HD’s side effects, talk with your doctor or pharmacist. They may also provide information about managing certain side effects of this drug.

Note: The Food and Drug Administration (FDA) tracks side effects of drugs it has approved. If you would like to notify the FDA about a side effect you’ve had with Asacol HD, you can do so through MedWatch.

Mild and serious side effects

Mild and serious side effects of Asacol HD are listed in the table below. This table does not include all of Asacol HD’s possible side effects.

Mild side effects* Serious side effects
cough kidney problems, such as kidney failure or kidney stones
headache • mesalamine-induced† acute intolerance syndrome, which is a condition that mimics the symptoms of ulcerative colitis
influenza (the flu) • severe skin reactions, such as Stevens-Johnson syndrome and toxic epidermal necrolysis
common cold allergic reaction
fever  
digestive problems  

Most times, mild side effects of a drug go away within a few days or a couple of weeks. Talk with your doctor or pharmacist if any side effects become severe or don’t go away.

Serious side effects from Asacol HD aren’t common, but they are possible. If you have serious side effects, call your doctor right away. However, if you’re having a medical emergency or your symptoms feel life threatening, call 911 or a local emergency number.

* This is not a complete list of Asacol HD’s mild side effects. To learn about other mild side effects of this drug, ask your doctor or pharmacist. Or you can view the drug’s prescribing information.
† Mesalamine is the active drug in Asacol HD.
‡ An allergic reaction is possible after taking Asacol HD. However, this side effect wasn’t reported in clinical studies. To learn more about allergic reaction, see below.

Allergic reaction

As with most drugs, some people can have an allergic reaction after taking Asacol HD. A more severe allergic reaction is rare but possible.

Allergic reactions were not reported in clinical studies of Asacol HD. However, they can still happen.

Possible symptoms of mild and serious allergic reactions are listed in the table below.

Mild allergic reaction symptoms Serious allergic reaction symptoms
flushing • swelling under your skin, possibly in your hands, feet, lips, or eyelids
rash • swelling in your throat or mouth
• itching trouble breathing

If you have an allergic reaction to Asacol HD, call your doctor right away. This is important to do because the reaction could become severe.

However, if you’re having a medical emergency or your symptoms feel life threatening, call 911 or a local emergency number.

Asacol HD: Alternatives

Doctors may prescribe drugs other than Asacol HD for your condition. Certain drugs may work better for you than others.

Asacol HD is used to treat ulcerative colitis. Here’s a summary of other drugs that doctors sometimes prescribe for this condition.

To learn more about one alternative to Asacol HD, view the following article:

Your doctor can tell you about other similar drugs, such as mesalamine (Delzicol).

For more information about alternatives to Asacol HD, ask your doctor. They can tell you about other medications that could be prescribed for your condition.

Asacol HD: Uses

Prescription drugs, such as Asacol HD, are approved by the Food and Drug Administration (FDA) to treat certain conditions. Doctors sometimes prescribe drugs off-label for other conditions. With off-label use, doctors prescribe a drug for a purpose other than what it’s approved for.

Using Asacol HD for ulcerative colitis

The FDA has approved Asacol HD to treat ulcerative colitis (UC) in adults.

With UC, you have inflammation in the large intestine. (The large intestine is part of your digestive tract and includes your colon and rectum.) This inflammation leads to ulcers (sores) in the large intestine, which cause the symptoms of UC.

With UC, you may have episodes of flares (active symptoms) and episodes of remission (no symptoms).

Below are symptoms that can happen during a UC flare:

Doctors can prescribe Asacol HD for taking short-term during a UC flare that’s causing moderate to severe symptoms.

Asacol HD’s limitation of use

The manufacturer of Asacol HD has noted a limitation to the drug’s use. This is a situation in which doctors may not prescribe the drug.

It’s not known whether Asacol HD is safe or effective when taken for longer than 6 weeks. For this reason, doctors usually won’t prescribe the drug for longer than 6 weeks.

Your doctor will determine exactly how long you’ll take Asacol HD.

Using Asacol HD in children

Doctors typically don’t prescribe Asacol HD for use in children. The drug is only approved for use in adults.

Finding a healthcare professional for Asacol HD

If you’re interested in treatment with Asacol HD, search here to find a doctor who might prescribe it. To prepare for your appointment, you can visit Healthgrades’s appointment guide for ulcerative colitis.

Asacol HD: Questions you may have

Here are some common questions about Asacol HD and brief answers to them. If you’d like to know more about these topics, ask your doctor.

Is Asacol HD taken in 400-mg doses?

No, Asacol HD is not taken in doses of 400 milligrams (mg). Instead, the drug’s typical dosage for ulcerative colitis is 1,600 mg (two 800-mg tablets) three times daily.

Mesalamine (the active drug in Asacol HD) was available in the past as 400-mg delayed-release (DR) tablets. (DR means that the drug’s release is delayed until the tablet reaches your large intestine.) This form was known as brand-name Asacol. However, Asacol is no longer on the market.

For more information about the drug’s recommended dosage, see the “Asacol HD: Dosage” section above. You can also talk with your doctor or pharmacist.

Does Asacol HD treat Crohn’s disease?

Asacol HD isn’t currently approved to treat Crohn’s disease. With Crohn’s disease, you have inflammation in the digestive tract. (The digestive tract begins at the mouth and ends at the anus. It includes the stomach, small intestine, and large intestine.)

In fact, the American College of Gastroenterology recommends against using mesalamine to treat Crohn’s disease. (Mesalamine is the active drug in Asacol HD.) This is because the drug hasn’t been shown to be effective in treating this condition. For this reason, doctors aren’t likely to prescribe Asacol HD to treat Crohn’s disease.  

If you have Crohn’s disease, talk with your doctor about other options that may be better for treating your condition.

Are there long-term side effects of Asacol HD?

Possibly. Most side effects of Asacol HD are expected to last only a few days or weeks. However, the drug may cause side effects that continue for longer.

For example, in rare cases, Asacol HD may cause kidney failure or severe skin reactions. Examples of these skin reactions include Stevens-Johnson syndrome and toxic epidermal necrolysis.

Kidney failure can cause long-term effects such as high blood pressure and heart failure. And severe skin reactions can cause other long-term effects, such as scars and vision problems.

To learn more about what to expect while taking Asacol HD, talk with your doctor or pharmacist.

Will stopping Asacol HD cause withdrawal symptoms?

It’s not likely. Withdrawal symptoms are side effects that can happen if you stop taking a drug your body has become used to. However, these symptoms weren’t reported in clinical studies of Asacol HD.

Keep in mind that Asacol HD is used for the short-term treatment of ulcerative colitis that’s causing moderate to severe symptoms. The drug can be taken for up to 6 weeks. After you stop taking Asacol HD, it’s possible for the symptoms of UC to return. In this case, your doctor may prescribe a different treatment to ease your symptoms.

Asacol HD: Cost

Like other medications, prices for Asacol HD may vary. The drug’s price will depend on factors such as:

Cost considerations for Asacol HD

Here’s a list of things to consider when looking into the cost of Asacol HD.

  • Option for a 90-day supply. For some drugs, it’s possible to get a 90-day supply. If this option is approved by your insurance company, it can help lower the cost of the drug. It can also help you avoid frequent trips to your pharmacy. If you’d like to learn more about this option, ask your doctor, pharmacist, or insurance company.
  • Possible cost assistance options. Financial assistance to help lower the cost of Asacol HD may be available. Visit the NeedyMeds website to learn more and see if you’re eligible for support. Also, check out this article to learn about ways to save on prescription drugs.
  • Use of a mail-order pharmacy. Asacol HD may be dispensed through mail-order pharmacies. Getting your prescription through a mail-order pharmacy could lower its cost. It can also allow you to get the drug without leaving home. To find out more about this option, check with your doctor, pharmacist, or insurance company.
  • Availability of a generic form. Asacol HD comes in a generic form called mesalamine. A generic drug is an exact copy of the active drug in a brand-name medication. Generics are typically less expensive than brand-name drugs. If your doctor prescribes Asacol HD, but you want to know about using mesalamine, talk with your doctor about which option might be better for you. Also, check your insurance plan because it might cover just one form or the other.

Asacol HD: Consuming alcohol during treatment

There is no known interaction between alcohol and Asacol HD.

However, alcohol can worsen the symptoms of ulcerative colitis (UC), which Asacol HD is used to treat. It’s generally recommended that people with UC avoid alcohol. For this reason, it may be best to avoid alcohol while taking Asacol HD.

If you drink alcohol, talk with your doctor. They can advise how much alcohol is safe to consume during Asacol HD treatment.

Asacol HD: Interactions

Asacol HD may interact with other medications and certain supplements. The drug isn’t known to interact with any foods.

Different interactions can cause different effects. Some interactions can interfere with a drug’s effectiveness. Others can increase a drug’s side effects or cause them to be severe.

If any of the interactions listed below might pertain to you, talk with your doctor. They can tell you what you need to do to avoid the interaction.

  • Asacol HD and certain medications. Because Asacol HD may interact with the following drugs, your doctor may recommend that you don’t take it with these drugs. Examples include:
  • Asacol HD and herbs and supplements. Certain herbs and supplements may interact with Asacol HD. An example is iron supplements.
  • Asacol HD and foods. Asacol HD isn’t known to interact with any foods. If you have questions about eating certain foods while taking Asacol HD, talk with your doctor or pharmacist.
  • Asacol HD and lab tests. In some cases, medications can affect the results of certain lab tests. This is possible with Asacol HD and urine tests for normetanephrine. (This substance is formed when your body breaks down a hormone called norepinephrine.) Doctors use this test to detect certain tumors.

Asacol HD: How to take

Your doctor will recommend how you should take Asacol HD. It’s important that you take the drug exactly as your doctor instructs.

Asacol HD comes as a delayed-release (DR)* oral tablet. You’ll take the drug by swallowing the tablet.

* DR means that the drug’s release is delayed until the tablet reaches your large intestine. To learn more, see the “Asacol HD: How it works” section below.

Questions about taking Asacol HD

Here’s a list of common questions related to taking Asacol HD.

  • When should I take Asacol HD? You’ll likely take Asacol HD three times a day. Try these tips to help avoid missing doses of Asacol HD. You could also set an alarm, use a timer, or download a reminder app on your phone.
  • Do I need to take Asacol HD with food? No, you’ll take Asacol HD on an empty stomach. To do so, you’ll take each dose at least 1 hour before or 2 hours after a meal.
  • Can Asacol HD be chewed, split, or crushed? Asacol HD should not be chewed, split, or crushed. You’ll swallow the tablets whole.
  • Is there a best time of day to take Asacol HD? No, there isn’t a best time of day to take Asacol HD. You’ll likely take the drug every 8 hours (three times daily).

Asacol HD: How it works

Asacol HD is approved to treat ulcerative colitis (UC). UC is caused by inflammation in the large intestine. (The large intestine is part of your digestive tract and includes your colon and rectum.) To learn more about this condition, see the “Asacol HD: Uses” section above.

Asacol HD belongs to a class of drugs called aminosalicylates, which are a type of anti-inflammatory drug. The drug works by reducing inflammation in your large intestine. This helps ease the symptoms of UC.

Asacol HD tablets are delayed-release. This means they contain a special coating that keeps them from breaking down in your stomach. Instead, the tablets slowly break down in your large intestine. This allows the drug to be released and absorbed directly where the inflammation is located.

How long does Asacol HD take to start working?

Asacol HD starts working right after you take your first dose. However, it may take a few weeks before you notice your symptoms ease.

Asacol HD: Taking while pregnant

It isn’t known whether Asacol HD is safe to take during pregnancy. There haven’t been enough clinical studies of the drug during pregnancy to know for certain.

Your doctor can advise on the risks and benefits of taking Asacol HD while pregnant.

Asacol HD and birth control needs

Doctors aren’t sure whether it’s safe to take Asacol HD during pregnancy. Talk with your doctor about your birth control needs with Asacol HD if you’re sexually active and you or your partner can become pregnant. Your doctor can recommend whether you should use birth control with this medication.

Asacol HD: Taking while breastfeeding

Asacol HD passes into breast milk. The drug may cause diarrhea in a child who is breastfed.

If you’re breastfeeding or planning to breastfeed, talk with your doctor before taking Asacol HD. They can advise on the risks and benefits of taking the drug while breastfeeding.

Asacol HD: Precautions

Tell your doctor about your health history before starting treatment with Asacol HD. Your doctor may not recommend this medication if you have certain factors affecting your health or specific medical conditions.

These factors and conditions include those listed below.

  • Liver disease. Asacol HD may increase the risk of liver failure in people who have liver disease. If you have liver disease, your doctor can recommend whether it’s safe to take Asacol HD.
  • Skin conditions. Asacol HD may cause photosensitivity (extreme skin sensitivity to sunlight) in people with certain skin conditions. If you have skin conditions such as atopic dermatitis (eczema), it may be best to limit your exposure to sunlight while taking the drug. It’s also recommended to wear sunscreen and protective clothing, such as long sleeves and a hat, while outdoors.
  • Kidney problems. Asacol HD can cause kidney problems as a side effect. Examples include kidney failure and kidney stones. If you already have kidney problems, the drug may worsen your condition. Your doctor can advise whether Asacol HD is safe for you to take.
  • Increased risk of a high iron level. Asacol HD tablets have an outer coating that contains iron. This coating can increase the risk of high iron levels in the blood for people with certain factors. Examples of these factors include receiving frequent blood transfusions or taking iron supplements. If you have these factors, your doctor can advise whether Asacol HD is safe for you to take.
  • Allergic reaction. Your doctor will likely not prescribe Asacol HD if you’ve had an allergic reaction to it or any of its ingredients. To find out about other treatment options, talk with your doctor.
  • Pregnancy. It’s not known whether Asacol HD is safe to take during pregnancy. If you’d like to learn more information about taking Asacol HD while pregnant, view the “Asacol HD: Taking while pregnant” section above.
  • Breastfeeding. Asacol HD may cause certain side effects in a child who is breastfed. If you’d like to learn more information about taking Asacol HD while breastfeeding, view the “Asacol HD: Taking while breastfeeding” section above.

To learn more about effects of Asacol HD that could be harmful, see the “Asacol HD: Side effects” section above.

Asacol HD: Overdose

Serious effects can occur if you take more than the recommended dosage of Asacol HD. Do not take more Asacol HD than your doctor recommends.  

Symptoms of overdose

Symptoms that an overdose could cause include:

What to do in case of overdose

Call your doctor if you think you’ve taken too much of this drug. Also, you can call the American Association of Poison Control Centers at 800-222-1222 or use their online tool. However, if your symptoms are severe, call 911 or your local emergency number. Or go to the nearest emergency room right away.

Asacol HD: Expiration, storage, and disposal

Here’s some information about Asacol HD’s expiration date, as well as how to store and dispose of the drug.

  • Expiration. Your pharmacist will add an expiration date to the label on Asacol HD’s bottle. This date is usually 1 year from the date the medication was dispensed to you. Expiration dates help ensure that a medication is effective during a period of time. The Food and Drug Administration (FDA) advises that you avoid using expired drugs. If you have an unused medication and it’s past the drug’s expiration date, talk with your pharmacist. They can let you know whether you might still be able to use the medication.
  • Storage. Many factors determine how long a medication remains good to use. These factors include how and where you store the drug. Asacol HD tablets should be stored at a room temperature between 68°F and 77°F (20°C and 25°C). The tablets can be stored temporarily at temperatures between 59°F and 86°F (15°C and 30°C), such as when traveling. Avoid storing it in areas where it could get damp or wet, such as bathrooms.
  • Disposal. It’s important to safely dispose of Asacol HD if you no longer need to take it and have unused medication. Doing so helps prevent others, including children and pets, from accidentally taking the drug. It also helps avoid causing harm to the environment. Ask your pharmacist for information about disposing of Asacol HD. Also, check out this page for several tips on safe medication disposal.

Asacol HD: Questions for your doctor

If you have questions about Asacol HD, talk with your doctor. They can help advise you on whether Asacol HD could be a good treatment option for you.

Here’s a list of questions you may want to ask your doctor:

  • Am I at a higher risk of any side effects with Asacol HD?
  • Can I switch to Asacol HD from another form of mesalamine?
  • Can you increase my dosage of Asacol HD if the drug isn’t working for me?

Your doctor may also tell you about other treatment options for your condition. You may find this article helpful in learning about alternative drugs for ulcerative colitis. And view our selection of videos on this condition.

Disclaimer: Healthgrades 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.

Medical Reviewer: Brittany A. Duke, PharmD, RPh
Last Review Date: 2022 May 21
THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.