DISCLAIMER: This publication is aimed at health professionals. The information is meant to provide updates on medication safety issues, and not as a substitute for clinical judgement. While reasonable care has been taken to verify the accuracy of the information at the time of publication, NPRA shall not be held liable for any loss whatsoever arising from the use of or reliance on this publication.

Overview of Products

Mesalazine is an anti-inflammatory agent compound that shares structural similarities with salicylates and non-steroidal anti-inflammatory drugs (NSAIDS), such as acetylsalicylic acid.^1,2 It is indicated for the induction of clinical and endoscopic remission in patients with mild to moderate active ulcerative colitis, as well as for the subsequent maintenance of remission.¹

Currently, there are 16 mesalazine products registered with the Drug Control Authority (DCA).³ These are available as single-ingredient products in both oral (tablets/granules) and rectal (suppositories/enemas) dosage forms.

Overview of Safety Concern

Idiopathic intracranial hypertension (IIH) is a disorder defined by chronically elevated intracranial pressure in the absence of a mass lesion, hydrocephalus, or other identifiable causes on clinical, laboratory, or radiological evidence.⁴ The condition most commonly affects women of childbearing age. Although the term "idiopathic" indicates that the underlying cause remains unknown, the condition is strongly associated with obesity.^5,6

The most prevalent symptom of IIH is headache, occurring in about 84% of cases.⁴ These are often worse in the morning. Other commonly reported symptoms include transient visual obscuration (defined as temporary darkening or blurring of vision), pulsatile tinnitus, dizziness, double vision, photophobia, and cognitive disturbances.^4,7,8 Patients may also experience neck and radicular pain.

Source of Safety Concern

The National Pharmaceutical Regulatory Agency (NPRA), through its global safety signal monitoring, noted that the United Kingdom Medicines and Healthcare Products Regulatory Agency (UK MHRA) had issued an update on the risk of IIH in patients treated with mesalazine.⁸ This followed a review of safety data, which concluded that mesalazine is very rarely associated with IIH. Consequently, an update to product information to include the risk was recommended.

Background of the Safety Issue

The exact mechanism by which medications and other factors trigger secondary intracranial hypertension is not fully understood and remains a subject of ongoing research. However, it has been suggested that an underlying inflammatory process may be involved in the pathophysiology of intracranial hypertension.⁹ Research also suggests that certain medications may influence cerebrospinal fluid dynamics and intracranial pressure regulation, thereby contributing to the development of intracranial hypertension.⁶

In one published case, a patient on long-term therapy (3 years) presented with chronic headaches and visual impairment secondary to elevated intracranial pressure.¹⁰ When mesalazine was discontinued, her intracranial pressure normalised. After the reintroduction of mesalazine, symptoms re-emerged within 15 days and resolved again upon discontinuation, suggesting a temporal relationship.

Local Adverse Drug Reaction Reports¹¹

To date, NPRA has received a total of 67 reports with 152 adverse events suspected to be related to mesalazine products. Based on the local database, there have been no reported cases of IIH associated with mesalazine use. However, other symptoms that may be related to increased intracranial pressure have been reported, including headache (4 reports) and neck pain (1 report).

Advice for Healthcare Professionals

• While NPRA is still reviewing this safety issue, should remain vigilant for the potential risk of IHH associated with mesalazine.
• Although IIH is not normally life-threatening, in rare cases it can cause serious vision problems if not identified early.
• Be cautious when prescribing mesalazine to patients with a known history of diagnosed or suspected IIH, or those with existing risk factors such as obesity and being of childbearing age.
• Advise patients to monitor and report symptoms of IIH, specifically severe or recurrent headaches, visual disturbances, or pulsatile tinnitus.
• Consider discontinuation of mesalazine if IIH symptoms occur and initiate prompt clinical management.
• Report all adverse events suspected to be related to the use of mesalazine products to the NPRA.

References:

1. National Pharmaceutical Regulatory Agency (NPRA). Mezavant XL 1200 Gastro-resistant, prolonged release Tablet. [Package Insert]. 2025 June [Cited 2026 Jan 13]. The Malaysian Product Registration Database (QUEST). Available from: https://www.npra.gov.my
2. Mesalazine. Available from: https://go.drugbank.com/drugs/DB00244
3. National Pharmaceutical Regulatory Agency (NPRA). QUEST3+ Product Search [Internet]. 2026 [cited 2026 Jan 15]. Available from: https://quest3plus.bpfk.gov.my/pmo2/index.php
4. Tham A, Lee AG. Idiopathic intracranial hypertension (IHH). [Internet]. Medscape; 2025 Mar 27 [cited 2026 Jan 15]. Available from: https://emedicine.medscape.com/article/1214410
5. Goudie C, Shah P, McKee J, Foot B, Kousha O, Blaikie A. The incidence of idiopathic intracranial hypertension in Scotland: a SOSU study. Eye [Internet] 2019;33(10):1570–6. Available from: https://doi.org/10.1038/s41433-019-0450-y
6. Mollan SP, Mytton J, Tsermoulas G, Sinclair AJ. Idiopathic Intracranial Hypertension: Evaluation of Admissions and Emergency Readmissions through the Hospital Episode Statistic Dataset between 2002–2020. Life [Internet] 2021;11(5):417. Available from: https://doi.org/10.3390/life11050417
7. Mehta D, El-Hunjul M, Yacoub H. Idiopathic intracranial hypertension related to Chronic use of mesalamine: a case report and literature review. Journal of Neurology Research [Internet] 2019;9(3):39–40. Available from: https://doi.org/10.14740/jnr537
8. Medicines and Healthcare products Regulatory Agency (MHRA). Mesalazine and idiopathic intracranial hypertension [Internet]. 2025 Dec 4 [Cited 2026 Jan 15]. Available from: https://www.gov.uk/drug-safety-update/mesalazine-and-idiopathic-intracranial-hypertension
9. Khanna RK, Hage R, Hage A, Polin V, Sené T, Vignal-Clermont C. Mesalazine treatment causing resolution of intracranial hypertension secondary to ulcerative colitis. Medicine [Internet] 2018;97(49):e13365. Available from: https://doi.org/10.1097/md.0000000000013365
10. Rosa N, Giamundo A, Jura A, Iaccarino G, Romano A. Mesalazine-associated benign intracranial hypertension in a patient with ulcerative colitis. American Journal of Ophthalmology [Internet] 2003;136(1):212–3. Available from: https://doi.org/10.1016/s0002-9394(02)02275-4
11. National Pharmaceutical Regulatory Agency (NPRA). The Malaysian National ADR Database (QUEST) [Internet]. 2026 [cited 2026 Jan 16]. Available from: https://www.npra.gov.my (access restricted)

Written by: Azura Abdullah

Reviewed/Edited by: Lim Sze Gee, Dr Rema Panickar, Noor'ain Shamsuddin, Norleen Mohamed Ali