About fentanyl

Fentanyl is a analgésico opioide fuerte that is used to treat severe or chronic pain.

If you have long-term (chronic) pain, you may be prescribed a fentanyl skin patch. This is called transdermal fentanyl. The patch releases fentanyl slowly over time to give continuous pain relief.

Sometimes, pain may still break through. This is called breakthrough pain. In these cases, fentanyl may be given in other forms, such as lozenges, tablets, films, or nasal sprays, which are taken when needed for fast pain relief.

Fentanyl can also be given as an injection during surgery to help control pain.

It works by binding to certain tiny areas, called opioid receptors, in your brain and spinal cord (central nervous system). This leads to a decrease in the way you feel pain and your reaction to pain.

Common side effects of fentanyl include:

• Estreñimiento.

• Náuseas.

• Estar enfermo (vómitos).

• Sentirse mareado.

• Feeling sleepy or tired.

• Problemas respiratorios.

• Dolor de cabeza.

• Stomach (tummy) pain.

You will find a full list in the manufacturer's information leaflet supplied with your medicine.

Los efectos no deseados a menudo mejoran a medida que su cuerpo se adapta al nuevo medicamento, pero hable con su médico o farmacéutico si algún efecto secundario persiste o se vuelve problemático.

If you experience other symptoms which you think may be due to fentanyl, speak with your doctor or pharmacist for further advice.

Some medicines are not suitable for people with certain conditions. Before taking fentanyl it is important that your doctor knows:

• Si estás embarazada o amamantando.

• Si tienes un problema con el funcionamiento de tu hígado, o un problema con el funcionamiento de tus riñones.

• If you have a sore mouth or diabetes. This is because some brands of fentanyl may not be suitable for you to take.

• Si tienes problemas de próstata o alguna dificultad para orinar.

• If you have any breathing problems, such as asma o enfermedad pulmonar obstructiva crónica (EPOC).

• If you have been told you have baja presión arterial.

• Si tienes algún problema con tu tiroides o glándulas suprarrenales.

• If you have epilepsia.

• Si tienes un problema con tu conducto biliar.

• Si has estado estreñido por más de una semana o tienes un problema inflamatorio intestinal.

• If you have a condition causing muscle weakness, called miastenia gravis.

• If you have recently had a severe head injury, or have a brain tumour.

• Si alguna vez has sido dependiente de las drogas o el alcohol.

• Si alguna vez has tenido una reacción alérgica a un medicamento.

• Si está tomando otros medicamentos. Esto incluye cualquier medicamento que esté tomando y que esté disponible para comprar sin receta, así como medicamentos herbales y complementarios.

• Use fentanyl exactly as prescribed by your doctor.

• Fentanyl comes in different forms, so your doctor or pharmacist will explain how to use yours.

• When you first start fentanyl, your dose is usually increased gradually to find the right level for your pain and reduce side effects.

• Once the correct dose is found, keep using the same dose unless your doctor tells you to change it.

• Check the label on the pack for your dose and follow the instructions carefully.

• If you are unsure about the dose or how to use it, ask your pharmacist for advice.

If you are using fentanyl patches

• Open the pouch carefully and check the patch is not damaged. Keep the pouch to safely dispose of the patch later.

• Apply to clean, dry, healthy skin on your upper arm or upper body. Press firmly for about 30 seconds, especially around the edges. Avoid touching the sticky side. Wash your hands after applying.

• It may take up to 24 hours for the patch to reach full effect, so you may need other pain relief during this time.

• Leave the patch on for 72 hours (3 days). After this, remove it and apply a new patch to a different area. Change it at the same time of day each time.

• Dispose of used patches safely: fold it sticky side inwards, put it in the pouch, and follow your doctor’s instructions. Keep out of reach of children.

• Avoid heat sources on the patch, such as heating pads, hot water bottles, electric blankets, heated water beds, long hot baths, saunas, or sunbathing. Heat can release too much fentanyl and increase the risk of overdose.

• Tell your doctor if you develop a high temperature, as this can also increase fentanyl absorption.

• Always check your brand when getting a new prescription. Different brands may release fentanyl differently; stick to the same brand unless your doctor advises otherwise.

• Watch for signs of too much fentanyl: shallow or weak breathing, extreme sleepiness, confusion, slurred speech, or severe dizziness. If these happen, remove the patch and contact your doctor immediately.

If you are using fentanyl lozenges (Actiq®)

• Use the applicator to move the lozenge around your mouth while you suck it. Let it touch your tongue and inside of your cheeks.

• Do not chew or swallow the lozenge. Fentanyl is absorbed through the lining of your mouth.

• If your mouth is dry, moisten it with water before using the lozenge.

• Suck one lozenge over about 15 minutes.

• If your pain has not eased within 15 minutes after finishing the lozenge, you may suck another one.

• Do not use more than two lozenges for one episode of pain, or more than four in 24 hours.

• If your pain is not controlled, tell your doctor.

If you are using fentanyl sublingual tablets (Abstral®)

• Place the tablet under your tongue and let it dissolve completely.

• Do not chew, suck, or swallow the tablet.

• You can moisten your mouth with water before use, but do not eat or drink while it is dissolving.

• If your pain hasn’t eased in 15-30 minutes, you may use one more tablet.

• Do not use more than two tablets for one episode of pain.

• Wait at least 2 hours before treating a new episode of breakthrough pain.

• If you have more than four episodes of breakthrough pain in 24 hours, tell your doctor.

• If pain is still not controlled, contact your doctor.

If you are using fentanyl buccal tablets (Effentora®)

• Place the tablet between your gum and cheek and let it dissolve completely.

• Do not chew, suck, or swallow the tablet.

• You can moisten your mouth with water before use, but do not eat or drink while it is dissolving.

• If after 30 minutes small pieces remain, you can swallow them with water.

• If pain hasn’t eased in 30 minutes, you may use another tablet on the other side of your mouth or under your tongue.

• Do not use more than two tablets for one episode of pain.

• Wait at least 4 hours before treating another episode of breakthrough pain.

• If pain is still not controlled, contact your doctor.

If you are using fentanyl nasal spray (PecFent®)

• Sit or stand while using the spray.

• Bend your head slightly forward and hold the spray upright.

• Close one nostril with a finger and insert the tip into the other nostril.

• Spray once while breathing in through your nose.

• If pain hasn’t eased in 10 minutes, use a second spray in the other nostril.

• Do not use more than two sprays for one episode of pain.

• Wait at least 4 hours before treating another episode.

• If pain is not controlled, or if you have more than four episodes of breakthrough pain in 24 hours, contact your doctor.

• Do not drink alcohol while taking fentanyl. Alcohol can increase side effects like dizziness and sleepiness.

• Fentanyl is only given for as long as needed. Long-term use can cause tolerance (the medicine works less) and dependence, which may lead to withdrawal symptoms if it is stopped suddenly. Your doctor will reduce your dose gradually when it’s no longer needed.

• Fentanyl can slow your reactions. Do not drive if you feel drowsy or dizzy. Even if you feel safe, carry proof that fentanyl is prescribed (such as prescription slip or patient leaflet).

• Tell your doctor, dentist, or other healthcare professional that you are taking fentanyl before having any procedures or dental treatment.

• Before taking other medicines check with a pharmacist that they are safe to take with fentanyl.

• Fentanyl is a controlled drug, so carry a letter from your doctor when travelling. For trips longer than three months, you must apply to the Home Office for a licence to take fentanyl with you.

• Keep all medicines out of the reach and sight of children. This includes used patches and part-finished lozenges.

• Almacenar en un lugar fresco y seco, lejos del calor y la luz directos.

How long does it take for fentanyl to work?

Fentanyl usually starts to work within minutes, although the exact timing depends on how it is taken. Injected fentanyl works in 1-5 minutes, lozenges or nasal sprays in 5-15 minutes, and fentanyl patches begin providing pain relief after 12-24 hours.

How long does fentanyl stay in your system?

Fentanyl can stay in your system for 1 to 3 days, depending on dose and method of use. It is typically detectable for up to 24 hours in blood, 1-3 days in urine, 48 hours in saliva, and up to 90 days in hair. Fentanyl patches may cause longer-lasting effects.

Is fentanyl addictive?

Yes, fentanyl is highly addictive, even when prescribed. It is a strong opioid painkiller that can cause physical dependence, tolerance, and opioid addiction, particularly with long-term or non-medical use.

Is fentanyl stronger than morphine?

Yes, fentanyl is much stronger than morphine. It is around 50 to 100 times more potent, meaning much smaller doses are needed to achieve the same level of pain relief.

What happens when you stop taking fentanyl?

Stopping fentanyl suddenly can cause withdrawal symptoms. Common symptoms include muscle aches, anxiety, sweating, feeling sick, diarrhoea, and sleep problems. Doctors usually recommend gradually reducing the dose to minimise withdrawal.