As Muslims around the world observe Ramadan, people living with chronic illnesses often face uncertainty over whether fasting is medically safe.
While fasting may offer spiritual and psychological benefits, evidence from the World Health Organization (WHO) and peer-reviewed studies shows that it can pose serious health risks for some patients, depending on the nature and severity of their condition.
WHO has repeatedly stressed that individuals with noncommunicable diseases should not fast without consulting healthcare professionals.
In its guidance on the prevention and control of noncommunicable diseases, updated in 2017 and 2019, the organization warns that prolonged fasting, dehydration, and changes in medication schedules may destabilize chronic conditions and increase the risk of complications.
Diabetes risks
Diabetes is the most extensively studied condition in relation to Ramadan fasting. The EPIDIAR study, published in Diabetes Care in 2004, analyzed data from more than 12,000 people with diabetes across 13 countries. It found that the risk of severe hypoglycaemia rose sevenfold among people with type 1 diabetes and fivefold among those with type 2 diabetes during Ramadan.
WHO guidance and international diabetes recommendations updated between 2021 and 2023 advise that people with poorly controlled diabetes, a history of severe hypoglycaemia, or those requiring intensive insulin regimens should not fast.
However, individuals with well-controlled type 2 diabetes may be able to fast safely under medical supervision, provided medication timing is adjusted, and blood glucose is monitored regularly.
Heart and kidney conditions
For patients with cardiovascular disease, fasting may be tolerated in stable cases but is dangerous in others. WHO cardiovascular health guidance updated in 2019 highlights dehydration and blood pressure fluctuations as key risks, particularly for patients taking diuretics or multiple antihypertensive drugs. Patients with recent heart attacks, unstable angina, or advanced heart failure are generally advised not to fast.
Chronic kidney disease also requires caution
Studies published between 2014 and 2016 in The Clinical Journal of the American Society of Nephrology indicate that fasting may worsen kidney function in patients with moderate to severe disease, especially during long fasting hours or in hot climates. WHO recommendations support exempting these patients, as dehydration may accelerate disease progression.
Respiratory illness and exemptions
People with severe asthma or chronic obstructive pulmonary disease may face difficulties if fasting interferes with regular medication use, particularly inhalers, according to the WHO respiratory disease guidance issued in 2020.
Importantly, WHO and Islamic teachings both emphasize that protecting health is paramount. Islam grants clear exemptions from fasting when illness may cause harm. Medical experts advise those who fast to maintain balanced meals, adequate hydration between iftar and suhoor, and to break the fast immediately if symptoms such as dizziness, confusion, or fainting occur.
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