Hidróxido de magnesio para el estreñimiento
Phillips' Milk of Magnesia
Revisado por pares por Sid DajaniÚltima actualización por Michael Stewart, MRPharmSÚltima actualización 21 Oct 2024
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Magnesium hydroxide is a laxative for occasional use only.
Take a dose at bedtime with a glassful of water.
If you are taking other medicines, do not take magnesium hydroxide within two hours (before or after) of your other medicines.
De un vistazo
Magnesium hydroxide is a medicine used to treat constipation, available as a liquid mixture.
It works by drawing fluid into your bowel, making stools softer and easier to pass.
Take it with water or milk at bedtime, but do not take it for more than three days.
Ask a pharmacist or doctor before taking if pregnant, have kidney/liver problems, or are on other medicines.
Do not take magnesium hydroxide at the same time as other medicines.
Drinking plenty of fluids and eating fibre also help with constipation.
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About magnesium hydroxide
Tipo de medicamento | A laxative |
Usado para | Estreñimiento |
También llamado | Phillips'® Milk of Magnesia |
Disponible como | Liquid mixture |
Estreñimiento is a common problem. It can mean either going to the toilet less often than usual to empty your bowels, or passing hard or painful stools. Constipation can be caused by a number of things. Not eating enough fibre or not drinking enough fluid can cause constipation. Some conditions (such as pregnancy) can cause constipation, as can a lack of exercise or movement (such as being ill in bed), and some medicines. Often, increasing the amount of fibre in your diet (such as by eating more fruit, vegetables, cereals and wholemeal bread) and drinking plenty of water each day can effectively prevent or relieve constipation. A laxative such as magnesium hydroxide can also be helpful, if used occasionally.
Magnesium hydroxide works by drawing fluid into your bowel, which makes your stools softer and easier to pass. It can be bought without a prescription at pharmacies and other retail outlets.
Before taking magnesium hydroxide
Volver al contenidoTo make sure that this is the right treatment for you, ask a pharmacist or doctor for advice before you start taking magnesium hydroxide if:
You are pregnant. This is because if you are expecting a baby, medicines should only be taken on the advice of a doctor.
You have problems with the way your kidneys work, or problems with the way your liver works.
You have severe tummy (abdominal) pain, cramping, or sickness (vomiting).
You are taking any prescription medicines. This is because magnesium hydroxide can reduce the absorption of many medicines.
You have ever had an allergic reaction to a medicine.
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How to take magnesium hydroxide
Volver al contenidoBefore you start taking the mixture, read the manufacturer's printed information attached to the pack. It will give you more information about magnesium hydroxide and how to take it.
Shake the bottle well to make sure the medicine is evenly mixed before pouring out a dose. The dose for an adult is 30-45 ml (six to nine 5 ml spoonfuls). The dose for a child aged 3-12 years is 5-10 ml (one or two 5 ml spoonfuls), although magnesium hydroxide should solo be given to a child on the advice of a healthcare professional. Swallow the dose with a glass of water or milk at bedtime. The water/milk helps the magnesium hydroxide to work so it is important that you drink a glassful. It is also especially important if you are elderly, or at risk of becoming lacking in fluid in the body (dehydrated) for any reason.
Magnesium hydroxide is a laxative for occasional use only - do not take it for more than three consecutive days. It must not be taken to prevent constipation or to 'keep you regular'. If you are concerned about your bowel habit, please speak with your doctor for advice.
Do not take magnesium hydroxide at the same time as any other medicines. This is because it can interfere with the way your body absorbs other medicines and may stop them from working properly. Try to leave at least two hours both before and after a dose of magnesium hydroxide before you take any other medicines.
Obteniendo el máximo de tu tratamiento
Volver al contenidoIt is important for you to drink plenty while you are constipated. Adults should aim to drink at least two litres (about 8-10 cups) of fluid per day. Most sorts of drink will do but as a start, try just drinking a glass of water 3-4 times a day in addition to what you normally drink.
Intenta comer una dieta equilibrada que contenga alimentos ricos en fibra, como panes y cereales integrales, frutas y verduras, arroz integral y pasta integral. Si no estás acostumbrado a una dieta alta en fibra, puede ser mejor aumentar la cantidad de fibra que consumes gradualmente.
Mantener tu cuerpo activo te ayudará a mantener en movimiento tu sistema digestivo, así que intenta hacer ejercicio diario de forma regular.
You may wish to include some foods in your diet that contain sorbitol. Sorbitol is a naturally occurring sugar. It is not digested very well and draws water into your bowel which has an effect of softening stools. Fruits (and their juices) that have a high sorbitol content include apples, apricots, gooseberries, grapes (and raisins), peaches, pears, plums, prunes, raspberries and strawberries.
You can read more about how to prevent or treat constipation in the separate condition leaflets called Estreñimiento (for adults) and Estreñimiento en Niños.
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Can magnesium hydroxide cause problems?
Volver al contenidoOccasionally, people who have taken magnesium hydroxide have experienced digestive symptoms such as mild diarrhoea and stomach cramps. If either of these happens to you, stop taking it. Other side-effects are unlikely but if you do experience any other symptoms, speak with a doctor or pharmacist for further advice.
How to store magnesium hydroxide
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.
Check the label on the bottle for an expiry date. Once a bottle of mixture has been opened, it may need to be used within a period of time, or discarded.
Información importante sobre todos los medicamentos
Volver al contenidoInformación importante sobre todos los medicamentos
If you suspect that you or someone else might have taken an overdose of this medicine, go to the accident and emergency department of your local hospital. Take the container with you, even if it is empty.
Si vas a someterte a una operación o a un tratamiento dental, informa a la persona que realiza el tratamiento sobre los medicamentos que estás tomando.
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 Sitio web de Yellow Card.

¿Inseguro sobre mezclar medicamentos?
Verifica posibles interacciones entre medicamentos, suplementos y alimentos antes de tomarlos juntos.
Preguntas frecuentes
What kind of constipation is magnesium hydroxide most suitable for?
Magnesium hydroxide is used as a laxative, specifically for occasional constipation. It should not be used regularly to 'keep you regular' or to prevent constipation.
How quickly can I expect magnesium hydroxide to work after taking it?
The article states that magnesium hydroxide should be swallowed with a glass of water or milk at bedtime. This suggests it is intended to work overnight or by the next morning, but does not specify an exact timeframe.
Is it safe to crush or mix magnesium hydroxide with other foods or drinks besides water or milk?
The instructions advise shaking the bottle well and swallowing the dose with a glass of water or milk at bedtime. There is no information provided about crushing or mixing it with other foods or drinks.
What should I do if I forget to take a dose of magnesium hydroxide?
The article provides general instructions on how to take the medicine but does not specifically advise on what to do if a dose is missed. It does state that it's for occasional use only and not for more than three consecutive days.
Are there types of drinks I should avoid when taking magnesium hydroxide?
The article does not specify any drinks to avoid. It recommends taking the dose with water or milk and generally encourages drinking plenty of fluid, including different sorts of drinks, when constipated.
Can I give magnesium hydroxide to an infant or a child younger than 3 years old?
The recommended dose for a child is for those aged 3-12 years, and even then, magnesium hydroxide should only be given on the advice of a healthcare professional. There is no information provided for infants or children younger than 3 years old.
Lecturas adicionales y referencias
- Manufacturer's PIL, Magnesium Hydroxide Mixture BP; Thornton & Ross Ltd, The electronic Medicines Compendium. Dated July 2020.
- Medicamentos Completos BNF 89ª Edición; Asociación Médica Británica y Sociedad Real de Farmacia de Gran Bretaña, Londres.
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Sobre el autorVer biografía completa

Michael Stewart, MRPharmS
Gerente de Revisión de Folletos de Medicamentos – Contratista, Farmacéutico
BPharm (Hons), MRPharmS
Michael es un farmacéutico comunitario que ejerce en Midlands y South Yorkshire con más de 20 años de experiencia asesorando sobre medicamentos y condiciones médicas. Tiene una sólida formación en capacitación en atención médica, habiendo producido e impartido cursos de formación para equipos de farmacia y personal de entornos de atención residencial, incluidas enfermeras. También ha contribuido a juntas asesoras de farmacia para la gestión de condiciones de baja gravedad en la comunidad.
Acerca del revisor

Sid Dajani
Sultan Dajani se graduó en la Escuela de Farmacia de Londres en 1994 y se convirtió en el miembro más joven elegido para el consejo de la Sociedad Real de Farmacia desde su fundación en 1842.
Historial del artículo
La información en esta página está escrita y revisada por pares por clínicos calificados.
Next review due: 18 Oct 2027
21 Oct 2024 | Última versión

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