The NHS has released a warning for people who take levothyroxine to manage thyroid conditions. With an estimated 33 million prescriptions issued every year across the UK, levothyroxine is among the most frequently prescribed medicines provided by the NHS.Levothyroxine is mainly used to treat an underactive thyroid, a condition medically known as hypothyroidism. Depending on a patient’s needs and a GP’s assessment, the medicine is usually prescribed either as a tablet or as a liquid taken by mouth.What Is Levothyroxine?For many patients, levothyroxine is effective in helping the body restore normal thyroid hormone levels. However, the NHS has stressed that the medication is not suitable for everyone. In certain cases, taking levothyroxine may raise the risk of complications linked to other existing health problems.The NHS website explains that while most adults and children can safely take levothyroxine, there are specific situations where it may not be recommended. These restrictions are based on a person’s medical history and current health conditions.People Who May Not Be Able to Take LevothyroxineAccording to NHS guidance, levothyroxine may not be suitable if any of the following apply:You have a heart condition such as angina, heart disease, or heart failureYou have a condition that affects your adrenal glandsYou have previously suffered a heart attackYou have an overactive thyroid that produces excess thyroid hormone, known as thyrotoxicosisYou have diabetesYou have had an allergic reaction to levothyroxine or another medicine in the pastYou have high blood pressurePatients are advised to inform their GP or specialist about any of these conditions before starting treatment.Levothyroxine: Possible Side Effects to Be Aware OfLevothyroxine can cause a range of side effects, some of which may require urgent medical attention. Common side effects associated with the medication include:Flushing or excessive sweatingFeeling restless, anxious, or overly energeticDifficulty sleepingNauseaHeadachesVomitingShaking or tremblingDiarrhoeaMuscle crampsThe NHS notes that this is not a complete list, and other side effects may occur. Patients are advised to read the information leaflet included with their medication for full details.Levothyroxine: When to Seek Medical HelpAlthough these side effects can be unpleasant, they are usually mild and do not typically require a hospital visit. If symptoms persist or become troublesome, the NHS recommends speaking to a doctor or pharmacist for advice.However, certain symptoms should not be ignored. If you notice a fast or irregular heartbeat while taking levothyroxine, you should contact a doctor or call NHS 111 as soon as possible.More serious symptoms require immediate action. Anyone experiencing chest pain while on levothyroxine is advised to call 999 without delay, as this could signal a medical emergency.Disclaimer: This article is for general information only and is not a substitute for medical advice. Levothyroxine should be taken only as prescribed by a qualified healthcare professional. Do not start, stop, or change your medication without consulting your doctor. If you experience severe symptoms or a medical emergency, seek immediate medical attention or call emergency services.