Health

NHS issues important warning for millions taking Levothyroxine for thyroid treatment

Why having high blood pressure or diabetes could affect your thyroid assessment

January 01, 2026
NHS issues important warning for millions taking Levothyroxine for thyroid treatment
Here's why you should be careful before taking your thyroid medicine 

The NHS has issued a warning to anyone taking levothyroxine to treat their thyroid condition.

With millions of prescriptions of levothyroxine being handed out globally, the drug is one of the most commonly prescribed medicines from the NHS.

Levothyroxine is commonly used to treat an underactive thyroid gland, medically known as hypothyroidism.

Typically, it will be prescribed as either a tablet or a liquid that the patient swallows, depending on what the general physician thinks is more suitable.

While levothyroxine can be effective at treating an underactive thyroid in most cases, the NHS has warned that there are some people who should not be prescribed it.

This can be due to multiple reasons, including the drug increasing the risk of complications of other health conditions that an individual might have.

The NHS website states: "Levothyroxine can be taken by most adults and children. However, it’s not suitable for some people."

According to their guidelines, you may not be able to take levothyroxine if one of the following applies:

  • You have a heart problem, including angina, heart disease or heart failure
  • You have a health problem that affects your adrenal glands
  • You have previously had a heart attack
  • You have an overactive thyroid that produces too much thyroid hormone
  • You have diabetes
  • You have previously had an allergic reaction to levothyroxine or any other medicine
  • You have high blood pressure