5-ASA (Mesalamine, Sulfasalazine)
First-line treatment for mild-to-moderate ulcerative colitis. Available as oral tablets, suppositories, and enemas. Very safe — even safe in pregnancy.
This article is educational and does not replace your doctor's advice. Seek urgent care for any red-flag symptoms.
Drug class
Aminosalicylates (5-aminosalicylic acid)
Examples
Mesalamine (also called mesalazine): Pentasa, Asacol, Salofalk, Mezavant, Lialda. Sulfasalazine (Salazopyrin) — older form, also treats joint disease but more side effects.
How it works
5-ASA is a topical anti-inflammatory drug for the bowel lining. Different formulations release in different parts of the GI tract — important for matching to the location of disease. Reduces inflammation directly without major systemic effects.
What it treats
- Mild-to-moderate ulcerative colitis (induction and maintenance)
- Some forms used for Crohn's colitis (less effective than for UC)
- Sulfasalazine for IBD-related arthritis
How to take it
Oral mesalamine — many formulations and brands. Common: 2-4.8 g/day in 1-3 divided doses. Newer once-daily formulations (Mezavant) improve adherence.
Mesalamine suppositories (1 g) — for proctitis only; insert at bedtime.
Mesalamine enemas (4 g/60 mL) — for left-sided colitis; instill at bedtime, retain overnight.
Sulfasalazine — 2-4 g/day in divided doses; cheaper but more side effects.
Combination of oral + rectal therapy is more effective than either alone for left-sided UC.
Common side effects
- Nausea, abdominal pain, diarrhea (paradoxically!)
- Headache
- Sulfasalazine: nausea, headache, low sperm count (reversible), folate deficiency (need supplementation)
- Yellow-orange discoloration of urine, sweat, contact lenses (sulfasalazine)
Serious side effects — call your doctor
Severe abdominal pain or bloody diarrhea after starting
Possible mesalamine-induced colitis (paradoxical) — stop and see doctor.
Severe rash, fever, mouth sores
Possible Stevens-Johnson syndrome — emergency.
New shortness of breath or chest pain
Rare lung or heart inflammation — see your doctor.
Significant kidney function decline
Mesalamine nephritis — stop and assess.
Interactions
Sulfasalazine reduces folate absorption — supplement folate (especially in pregnancy planning). Limited interactions with most other drugs. Avoid combining mesalamine with other nephrotoxic drugs (NSAIDs, aminoglycosides) when possible.
Monitoring
Before starting: kidney function. During: kidney function every 6 months. CBC for sulfasalazine. Folate level for sulfasalazine. Periodic full liver function.
When and how to stop
In ulcerative colitis: long-term maintenance recommended even when in remission — prevents relapse and reduces colon cancer risk. Don't stop without doctor advice.
Pregnancy & breastfeeding
Mesalamine is considered SAFE in pregnancy and breastfeeding. Sulfasalazine is also acceptable but may need higher folate supplementation (5 mg/day). Continue therapy in pregnancy — uncontrolled IBD is more dangerous to mother and baby than the medication.
In the Saudi context
All 5-ASA formulations are widely available and covered by insurance. Many Saudi IBD centers have pharmacist-led adherence programs.
Questions to ask your doctor
Save this list or print it before your appointment — doctors appreciate prepared patients.
- Should I add a rectal mesalamine to my oral form?
- Can I take mesalamine in pregnancy?
- Does long-term mesalamine reduce my colon cancer risk?
Medically reviewed by: SGA Patient Education Panel · Last reviewed 24/04/2026