Propylthiouracil tablets
Revisado por pares por Sid DajaniÚltima actualización por Michael Stewart, MRPharmSLast updated 17 Apr 2025
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Keep your regular appointments with your doctor so that your condition can be monitored and any dose adjustments made. You will need to have regular blood tests.
The most common side-effects include stomach upset, aches and pains, a mild itchy rash, and changes to the way some things taste. These are not usually serious and soon pass.
Propylthiouracil can, however, cause serious liver problems in some people, so if you develop severe or persistent sickness, itching, any yellowing of your skin or the whites of your eyes (jaundice), or tummy pain, or if you generally feel unwell without cause, please contact your doctor for advice straightaway.
At a glance
Propylthiouracil is a medicine used to treat an overactive thyroid gland.
It reduces the amount of thyroxine hormone made by the thyroid gland.
Your doctor will advise you how many tablets to take daily, typically starting with a higher dose.
Take tablets around the same time each day, with or without food.
You will need regular blood tests to check your thyroid levels and liver function.
Contact your doctor straight away if you notice signs of liver problems like dark urine or yellow skin.
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About propylthiouracil
Tipo de medicamento | An antithyroid medicine |
Usado para | Hipertiroidismo |
Disponible como | Comprimidos |
Propylthiouracil is used to treat an overactive thyroid gland (hipertiroidismo). When the thyroid gland is overactive it makes too much of a hormone called thyroxine. The extra thyroxine causes many of the body's functions to speed up. This can lead to symptoms such as losing weight, excessive sweating, feeling irritable or shaky, and diarrhoea. You also may feel tired or worried, and women may develop menstrual problems.
Although the most commonly used antithyroid medicine in the UK is called carbimazol, some people are unable to take this medicine. If so, propylthiouracil is usually used as a suitable alternative. It works by reducing the amount of thyroxine made by your thyroid gland.
Before taking propylthiouracil
Volver al contenidoSome medicines are not suitable for people with certain conditions, and sometimes a medicine can only be used if extra care is taken. For these reasons, before you start taking propylthiouracil it is important that your doctor knows:
If you are pregnant or breastfeeding (even though propylthiouracil could still be prescribed for you).
Si tienes algún problema con el funcionamiento de tu hígado, o si tienes algún problema con el funcionamiento de tus riñones.
Si está tomando otros medicamentos. Esto incluye cualquier medicamento que se pueda comprar sin receta, así como medicamentos herbales y complementarios.
Si alguna vez has tenido una reacción alérgica a un medicamento.
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How to take propylthiouracil
Volver al contenidoBefore you start the treatment, read the manufacturer's printed information leaflet from inside the pack. It will give you more information about propylthiouracil, and will also provide you with a full list of the side-effects which you could experience from taking it.
Take the tablets exactly as your doctor tells you to. It is likely that you will be asked to take a high dose to start with, such as 4-8 tablets a day in divided doses. Your dose will then be gradually reduced to 1-3 tablets a day as your thyroid levels become more normal. Your doctor will give you the full directions for taking the tablets, and the information will also be printed on the label of the pack of tablets to remind you about what the doctor said to you.
Swallow your doses with a drink of water. Propylthiouracil tablets can be taken either with or without food.
Try to take your tablets around the same times of day each day. This will help you to remember to take propylthiouracil regularly.
Si olvida tomar una dosis, tómela tan pronto como lo recuerde (a menos que esté cerca la hora de su próxima dosis, en cuyo caso omita la dosis olvidada). No tome dos dosis juntas para compensar una dosis olvidada.
Obteniendo el máximo de tu tratamiento
Volver al contenidoTry to keep your regular appointments with your doctor. This is so your doctor can check on your progress and any dose adjustments can be made. You will need to have blood tests from time to time to check that you are on the correct dose and that your liver is working well. This is because propylthiouracil can occasionally cause serious liver problems.
Propylthiouracil should have some effect on your symptoms around three to four weeks after treatment starts. Your thyroid hormone levels should be stabilised within four to eight weeks. Continue to take the tablets for as long as you are advised to do so by your doctor.
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Can propylthiouracil cause problems?
Volver al contenidoAlong with their useful effects, most medicines can cause unwanted side-effects although not everyone experiences them. The table below contains some of the most common ones associated with propylthiouracil. You will find a full list in the manufacturer's information leaflet supplied with your medicine. The unwanted effects often improve as your body adjusts to the new medicine, but speak with your doctor or pharmacist if any of the following continue or become troublesome.
Common propylthiouracil side-effects | ¿Qué puedo hacer si experimento esto? |
Sentirse mal (náuseas) o vomitar (vómitos), malestar estomacal | Stick to simple foods - avoid rich or spicy food |
Headache, muscle aches and pains | Drink plenty of water and ask your pharmacist to recommend a suitable painkiller. If the aches continue, let your doctor know |
Changes in taste, feeling tired, mild skin rash and itching | Discuss these with your doctor if they become troublesome |
Importante: if you notice any of the following you should contact your doctor straightaway as it could be a sign of a problem with your liver:
Dark urine or light-coloured stools.
Estar enfermo (vómitos)
Pain in your tummy (abdomen).
Any yellowing of your skin or the whites of your eyes (jaundice).
Itchy skin or unexplained bruising.
Pérdida de apetito.
Any unexplained flu-like symptoms.
Feeling unusually tired or generally unwell.
Si experimenta cualquier otro síntoma que crea que puede deberse a las tabletas, hable con su médico o farmacéutico para obtener más consejos.
How to store propylthiouracil
Volver al contenidoMantenga todos los medicamentos fuera del alcance y la vista de los niños.
Almacenar en un lugar fresco y seco, lejos del calor y la luz directos.
Información importante sobre todos los medicamentos
Volver al contenidoInformación importante sobre todos los medicamentos
Nunca tome más de la dosis prescrita. Si sospecha que usted u otra persona podría haber tomado una sobredosis de este medicamento, acuda de inmediato al departamento de accidentes y emergencias de su hospital local. Lleve el envase con usted, incluso si está vacío.
Si compras algún medicamento, consulta con un farmacéutico que sea seguro tomarlo junto con tus otros medicamentos.
Si vas a someterte a una operación o tratamiento dental, informa a la persona que realiza el tratamiento sobre los medicamentos que estás tomando.
Este medicamento es para ti. Nunca lo des a otras personas, incluso si su condición parece ser la misma que la tuya.
No guardes medicamentos caducados o no deseados. Llévalos a tu farmacia local, que se encargará de desecharlos por ti.
Si tienes alguna pregunta sobre este medicamento, consulta a tu farmacéutico.
Informar efectos secundarios de un medicamento o vacuna
Si experimenta efectos secundarios, puede reportarlos en línea a través de Yellow Card website.

¿Inseguro sobre mezclar medicamentos?
Verifica posibles interacciones entre medicamentos, suplementos y alimentos antes de tomarlos juntos.
Preguntas frecuentes
What are the common symptoms of an overactive thyroid (hyperthyroidism) that propylthiouracil helps to manage?
An overactive thyroid can lead to symptoms such as losing weight, excessive sweating, feeling irritable or shaky, and diarrhoea. You might also feel tired or worried, and women could experience menstrual problems. Propylthiouracil works to reduce the amount of thyroxine a person's thyroid gland makes, which helps to alleviate these symptoms.
What should I do if I am pregnant or breastfeeding and my doctor prescribes propylthiouracil?
If you are pregnant or breastfeeding, it is important to inform your doctor. While propylthiouracil could still be prescribed in these circumstances, your doctor needs to be aware so they can provide the most appropriate care.
How long does it typically take for propylthiouracil to start working and for my thyroid levels to stabilise?
You should start to notice some effect on your symptoms around three to four weeks after beginning treatment with propylthiouracil. Your thyroid hormone levels are generally expected to stabilise within four to eight weeks. It's important to continue taking the tablets for as long as your doctor advises.
What are some of the less common but troublesome side-effects I should be aware of with propylthiouracil, beyond the more common ones?
Less common troublesome side-effects can include changes in taste, feeling tired, and a mild skin rash and itching. If any of these become problematic, you should discuss them with your doctor. Always refer to the manufacturer's leaflet for a full list of potential side-effects.
I'm taking other medicines; do I need to tell my doctor before starting propylthiouracil?
Yes, it is very important to tell your doctor about all other medicines you are taking. This includes any medicines you can buy without a prescription, as well as herbal and complementary medicines, to ensure they are safe to take with propylthiouracil.
What should I do if I forget to take a dose of propylthiouracil?
If you miss a dose, take it as soon as you remember. However, if it's almost time for your next dose, you should skip the missed dose. Do not take two doses at once to make up for a forgotten dose.
How should I store propylthiouracil tablets?
You should keep all medicines, including propylthiouracil, out of the reach and sight of children. Store them in a cool, dry place, away from direct heat and light.
Lecturas adicionales y referencias
- Manufacturer's PIL, Propylthiouracil 50 mg tablets; RPH Pharmaceuticals AB, The electronic Medicines Compendium. Dated December 2020.
- Medicamentos Completos BNF 89ª Edición; Asociación Médica Británica y Sociedad Real de Farmacia de Gran Bretaña, Londres.
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About the authorView full bio

Michael Stewart, MRPharmS
Medicine Leaflet Review Manager – Contractor, Pharmacist
BPharm (Hons), MRPharmS
Michael is a community pharmacist practicing in the Midlands and South Yorkshire with more than 20 years’ experience advising on medicines and medical conditions. He has a strong background in healthcare training, having produced and delivered training courses for pharmacy teams and staff of residential care settings, including nurses. He has also contributed to pharmacy advisory boards for the management of low acuity conditions in the community.
About the reviewer

Sid Dajani
Sultan Dajani qualified at the London School of Pharmacy in 1994 and became the youngest elected member of the Royal Pharmaceutical Society council since its founding in 1842.
Historial del artículo
La información en esta página está escrita y revisada por pares por clínicos calificados.
Next review due: 17 Apr 2028
17 Apr 2025 | Última versión

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