5-aminosalicylic acid (5-ASA or mesalamine) belongs to the group of medications known as anti-inflammatories. It is used to treat mild-to-moderate ulcerative colitis and mild-to-moderate Crohn's disease. 5-ASA acts by reducing inflammation in the bowel. It can be used to reduce symptoms and prevent flare-ups of these conditions.

Different brands of 5-ASA are designed to act on different places in the gastrointestinal tract (the digestion tube that runs from the mouth to the anus). Ulcerative colitis affects the colon and rectum only, while Crohn's disease affects the whole gastrointestinal tract. For this reason, some brands and forms of this medication are used to treat only ulcerative colitis, while others can be used to treat both Crohn's disease and ulcerative colitis.

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are using this medication, speak to your doctor. Do not stop using this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to use this medication if their doctor has not prescribed it.

Tablet: The recommended adult dose of this medication depends on the product selected. Swallow the tablets whole, ensuring that you do not break the outer coating. Take the tablets only as directed by your doctor. Do not change the number of tablets you take or how often you take them without first consulting your doctor.

Suppository, rectal suspension, rectal foam, and enema: The usual dose for suppositories, rectal suspension, and enema is 1 g to 4 g daily, usually at bedtime, or as prescribed by your doctor.

For the proper way to use these forms of the medication, check with your pharmacist.

Many things can affect the dose of a medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are using the medication without consulting your doctor.

It is important to use this medication exactly as prescribed by your doctor. Ulcerative colitis and Crohn's disease never completely go away. Once a flare-up of the illness has been controlled, your doctor will recommend a smaller dose to be taken daily to reduce the chance of the symptoms flaring up again. It is important to not stop the medication suddenly, even when you are feeling well. Doing so may cause the illness to flare up again.

If you miss a dose, take it as soon as possible and continue with your regular schedule. If it is almost time for your next dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store all forms of this medication at room temperature, protect them from light and moisture, and keep them out of the reach of children.

Do not use this medication if you:

• are allergic to 5-aminosalicylic acid or any ingredients of the medication
• are allergic to other salicylates (e.g., ASA)
• are not able to swallow tablets whole (tablets)
• have a gastric (stomach) or duodenal (intestinal) ulcer
• have a urinary tract obstruction
• have severely decreased kidney function
• have severely decreased liver function

Do not give this medication to children under 2 years of age.

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

• abdominal or stomach cramps or pain (mild)
• acne
• back pain
• bloating
• blood pressure changes
• changed sense of touch
• constipation
• decreased sperm count
• diarrhea (mild)
• dizziness
• ear or throat pain
• fatigue
• hair loss
• headache (mild)
• gas
• increased sensitivity of the skin to sunlight
• increased urge to have a bowel movement
• irritation of the rectal area
• muscle or joint pain
• nausea
• tiredness
• tremor
• vomiting
• weakness

Although most of these side effects listed below don't happen very often, they could lead to serious problems if you do not seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• burning pain or discomfort around the anus
• fever
• fast or pounding heartbeat
• kidney stones (e.g., blood in urine, increased need to urinate, back or groin pain)
• lupus-like rash ("butterfly" rash on face or arms where skin is exposed to sunlight)
• rectal bleeding
• sensation of numbness or tingling in the hands and feet
• severe headache
• severe stomach pain
• signs of anemia (low red blood cells; e.g., dizziness, pale skin, unusual tiredness or weakness, shortness of breath)
• signs of kidney problems (e.g., increased urination at night, decreased urine production, blood in the urine)
• signs of infection (symptoms may include fever or chills, severe diarrhea, shortness of breath, prolonged dizziness, headache, stiff neck, weight loss, or listlessness)
• signs of liver problems (e.g., nausea, vomiting, diarrhea, loss of appetite, weight loss, yellowing of the skin or whites of the eyes, dark urine, pale stools)
• skin rash and itching
• symptoms of lung inflammation (e.g., fever, cough, chills, shortness of breath, chest pain, wheezing)
• unusual bruising or bleeding
• vision changes
• worsening symptoms

Stop taking the medication and seek immediate medical attention if any of the following occur:

• signs of a serious allergic reaction (i.e., abdominal cramps, difficulty breathing, nausea and vomiting, or swelling of the face and throat)
• signs of acute intolerance syndrome (e.g., abdominal or stomach cramps or pain [severe], bloody diarrhea, chills, fever)
• signs of inflammation around the heart (e.g., fatigue, fever, difficulty breathing, cough)
• signs of pancreatitis (e.g., abdominal pain on the upper left side, back pain, nausea, fever, chills, rapid heartbeat, swollen abdomen)
• signs of a serious skin reaction (such as skin rash; red skin; blistering of the lips, eyes, or mouth; skin peeling; fever; or joint pain)
• symptoms of increased pressure in the brain (e.g., headache that worsens with eye movement, seeing light flashes, vision loss, dizziness, nausea, vomiting, ringing in the ears)

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Acute intolerance syndrome: This medication has been known to cause symptoms similar to those of worsening Crohn's disease or ulcerative colitis. If you experience the sudden onset of symptoms such as cramping, acute abdominal pain and bloody diarrhea, headache, rash, and possibly fever, contact your doctor immediately.

Allergy: Some people who are allergic to sulfasalazine or acetylsalicylic acid (ASA) also experience allergic reactions to mesalamine (5-ASA). Before you take 5-ASA, inform your doctor about any previous adverse reactions you have had to medications, especially sulfasalazine or ASA.

Contact your doctor at once if you experience signs of an allergic reaction such as skin rash, itching, difficulty breathing, or swelling of the face and throat.

Blood counts: Rarely, this medication can decrease certain blood cells, including neutrophils (a type of white blood cell that helps fight infection), red blood cells (which carry oxygen), and platelets (which help your blood to clot). Your doctor will do blood tests to monitor this. If you notice any signs of infection (e.g., fever, chills, or sore throat) or unusual bleeding or bruising, contact your doctor immediately.

Breathing problems: 5-ASA may increase the risk of allergic or hypersensitivity reactions for people who have conditions that affect their breathing. If you have asthma or chronic obstructive pulmonary disease (COPD) discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Fertility: This medication may cause a decrease in sperm production for men. If this is a concern, talk to your doctor.

Heart problems: People with heart problems may be at an increased risk of side effects of 5-ASA. If you have heart problems or a history of heart problems, including heart infections, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Kidney function: This medication is removed from the body by the kidneys. 5-ASA may not be removed from the body as quickly as expected if your kidneys are not working properly. This increases the likelihood of experiencing side effects. If you have reduced kidney function or kidney disease, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

5-ASA may also cause decreased kidney function and possibly kidney failure. If you notice a decrease in your amount of urine, swelling in your hands and lower legs, or unusual tiredness, contact your doctor as soon as possible.

Liver function: The use of this medication by people with reduced liver function has not been well studied. If you have reduced liver function or liver disease, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

This medication may cause decreased liver function. If you experience symptoms of liver problems such as fatigue, feeling unwell, loss of appetite, nausea, yellowing of the skin or whites of the eyes, dark urine, pale stools, abdominal pain or swelling, and itchy skin, contact your doctor as soon as possible.

Slow stomach emptying: The tablet form of 5-ASA may not work as well for people with a condition known as pyloric stenosis. If you have pyloric stenosis or have a history of slow emptying of the stomach, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Tablets in stool: Infrequently, what looks to be intact or partially intact tablets may appear in the stool. If this occurs repeatedly, consult your doctor.

Pregnancy: 5-aminosalicylic acid crosses the placenta and may affect the developing baby if taken by the mother during pregnancy. It should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.

Breast-feeding: This medication passes into breast milk. If you are breast-feeding and are taking 5-aminosalicylic acid, your baby could develop diarrhea. Talk to your doctor about whether you should continue breast-feeding.

Children: The safety and effectiveness of this medication for use by children have not been established.

There may be an interaction between 5-aminosalicylic acid and any of the following:

• aldesleukin
• antacids (e.g., aluminum hydroxide, calcium carbonate, sodium bicarbonate)
• azathioprine
• baricitinib
• cancer medications (e.g., alemtuzumab, cisplatin, doxorubicin, mitoxantrone, paclitaxel, vincristine)
• carbamazepine
• cyclosporine
• digoxin
• everolimus
• folic acid
• hydroxyurea
• lenalidomide
• linezolid
• methotrexate
• nonsteroidal anti-inflammatory drugs (NSAIDs; e.g., naproxen, ibuprofen)
• obinutuzumab
• propylthiouracil
• protein kinase inhibitors (e.g., dasatinib, imatinib, nilotinib)
• sirolimus
• tacrolimus
• varicella (chicken pox) vaccine
• warfarin
• zidovudine

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.