Nepal is facing an unexpected public health crisis: the very iodine added to salt to prevent thyroid disease is now triggering cases of hyperthyroidism at alarming rates. What began as a well-intentioned fortification program in the 1990s has backfired, with doctors reporting a dramatic increase in patients suffering from overactive thyroid conditions. The issue highlights how even essential nutrients can become harmful when consumed in excess, and how public health policies designed decades ago may no longer fit modern circumstances.

What Happens When Iodine Intake Becomes Too High?

Iodine is an essential mineral that the thyroid gland needs to produce hormones that regulate metabolism, heart rate, and body temperature. However, excessive iodine intake can overstimulate the thyroid gland, leading to hyperthyroidism, a condition where the thyroid produces more hormones than the body needs. This is particularly dangerous for people who already have thyroid nodules, Graves disease, or autoimmune conditions, where high iodine can make the overactive thyroid significantly worse.

A 26-year-old woman from Nawalparasi East in Nepal recently became a stark example of this problem. She was rushed to Bir Hospital, Nepal's largest medical facility, severely weakened and dangerously thin. Despite eating heavily, she had lost significant weight, her eyes were bulging and red, and she had visible swelling in her neck. Blood tests revealed the hallmark signs of hyperthyroidism: excessively high levels of T3 (triiodothyronine) and T4 (thyroxine) hormones, combined with critically low levels of TSH (thyroid-stimulating hormone), the hormone that signals the thyroid to produce more hormones.

"The woman complained that she felt hungry all the time. Despite eating heavily, however, she had lost significant weight. Her eyes were bulging, red and constantly tearing up. She also had visible swelling in the neck and goitre," explained Dr. Dipak Malla, a senior consultant endocrinologist at Bir Hospital.

Dr. Dipak Malla, Senior Consultant Endocrinologist at Bir Hospital

How Did Nepal's Salt Become So Iodine-Heavy?

The problem traces back to the 1990s, when Nepal began fortifying salt with iodine to combat iodine deficiency disorders, including goitre, a condition where the thyroid enlarges due to lack of iodine. At that time, the decision to fortify salt at 50 parts per million (ppm) made sense. Salt had to be transported across difficult terrain on the backs of men and animals, and stored openly in homes, meaning iodine would naturally dissipate during transit and storage. A higher fortification level was meant to ensure adequate iodine reached consumers.

Today, that reasoning no longer applies. Roads now reach almost every corner of Nepal, transport times have dramatically decreased, and storage methods have improved. Yet the iodine fortification level has remained unchanged at 50 ppm, nearly triple the World Health Organization's recommended range of 15 to 40 ppm.

A nationwide survey conducted in 2016, the Nepal Micronutrient Status Survey, revealed the extent of the problem. The study, jointly carried out by the World Health Organization, UNICEF, the U.S. Centers for Disease Control and Prevention, and Nepal's Ministry of Health and Population, found that over two-thirds (68 percent) of the population across the country was consuming iodine in excess of the recommended level. Among all salt samples collected, over nine in ten (91 percent) had iodine levels more than 15 ppm, while only four percent had no iodine at all.

The Rising Tide of Hyperthyroidism Cases

The consequences are now visible in Nepal's hospitals. Bir Hospital alone reports over 60 patients with thyroid disorders visiting for treatment daily. Multiple endocrinologists have noted that cases of hyperthyroidism have increased manifold over the past decade, which they primarily attribute to the high iodine levels in salt.

"The numbers are so high that I am busy attending patients from morning to evening," said Dr. Mahesh Dahal, an endocrinologist at Clinic One.

Dr. Mahesh Dahal, Endocrinologist at Clinic One

Hyperthyroidism causes a range of debilitating symptoms that can severely impact quality of life. Patients experience rapid heartbeat, which can exceed 200 beats per minute in severe cases. They suffer severe weight loss despite eating normally or even eating more than usual. Other symptoms include rapid trembling in the hands and fingers, difficulty sleeping, anxiety, and in women, heavy menstrual bleeding. In the most severe cases, excessive thyroid hormones can overstimulate the heart and lead to sudden death.

Steps to Recognize Hyperthyroidism Symptoms

• Metabolic Changes: Unexplained weight loss despite normal or increased appetite, persistent hunger, and rapid metabolism that burns calories quickly.
• Cardiovascular Symptoms: Heart palpitations, rapid pulse that may exceed 200 beats per minute, and increased risk of irregular heartbeat.
• Neurological and Physical Signs: Tremors in the hands and fingers, anxiety or irritability, difficulty sleeping, and heat intolerance with excessive sweating.
• Visible Physical Changes: Bulging eyes that may appear red and watery, visible swelling in the neck (goitre), and thinning hair.

Why Has Policy Change Been So Slow?

Despite clear evidence of harm, reducing the iodine content in salt has proven difficult. In 2024, a high-level meeting comprising representatives from the World Health Organization, UNICEF, and officials from various Nepali government ministries, including the Ministry of Agriculture and Livestock Development and the Department of Food Technology and Quality Control, agreed on a proposal to set an upper limit on salt's iodine content. The Department of Food Technology and Quality Control was tasked with incorporating experts' suggestions and forwarding the proposal to the Cabinet.

In October 2024, the government sent a nine-member team to Gujarat, India, to study how iodine fortification is handled there. The team discovered that India's iodine fortification levels for salt are lower than those prepared for Nepal, providing additional evidence that Nepal's current levels are unnecessarily high.

However, progress stalled. Health officials had planned to make a final decision on lowering iodine content only after a micronutrient status survey scheduled to begin in 2025. That survey was postponed indefinitely following the U.S. government's suspension of all USAID-funded programs worldwide, including in Nepal.

Experts argue that waiting for further data is no longer justified. If high iodine content in salt is causing more harm than good, they contend, the relevant authorities should act now rather than delay while more people develop hyperthyroidism. The evidence from hospital admissions, patient symptoms, and international comparisons already provides a compelling case for change.

Nepal's iodine crisis serves as a cautionary tale for public health policy: what works at one moment in history may become harmful as circumstances change. The challenge now is whether policymakers will act on the evidence before them or continue to wait for perfect data while a preventable health crisis unfolds.