GABAPENTIN Crescent 100mg, 300mg and 400mg capsules – patient leaflet, side effects, dosage

1. What Gabapentin is and what it is used for

Gabapentin belongs to a group of medicines used to treat epilepsy and peripheral neuropathic pain (long lasting pain caused by damage to the nerves).

The active substance in Gabapentin Capsules is gabapentin which belongs to a class of medicines called Gabapentinoids. This medicine has been prescribed to you and should not be given to anyone else.

Gabapentinoids can cause dependence, tolerance and addiction, and you may get withdrawal symptoms if you stop taking it or reduce the dose suddenly. Your prescriber should have explained how long you will be taking it for and, when it is appropriate to stop, how to do this safely. When your treatment is stopped, it is usually done gradually over a period which is specific to you and may occur over a period of weeks to months. If this medicine is being used for the treatment of epilepsy you must continue to take it as prescribed by your doctor.

Gabapentin are used for:

• Various forms of epilepsy (seizures that are initially limited to certain parts of the brain, whether the seizure spreads to other parts of the brain or not). The doctor treating you or your child 6 years of age and older will prescribe Gabapentin Capsules to help treat epilepsy when the current treatment is not fully controlling the condition. You or your child 6 years of age and older should take Gabapentin Capsules in addition to the current treatment unless told otherwise. Gabapentin Capsules can also be used on its own to treat adults and children over 12 years of age.
• Peripheral neuropathic pain (long lasting pain caused by damage to the nerves). A variety of different diseases can cause peripheral neuropathic pain (primarily occurring in the legs and/or arms), such as diabetes or shingles. Pain sensations may be described as hot, burning, throbbing, shooting, stabbing, sharp, cramping, aching, tingling, numbness, pins and needles etc.

2. What you need to know before you take Gabapentin

Do NOT take Gabapentin:

• If you are allergic (hypersensitive) to gabapentin or any of the other ingredients of Gabapentin Capsules (listed in section 6). Warnings and precautions

Talk to your doctor or pharmacist before you take Gabapentin Capsules:

• if you suffer from kidney problems your doctor may prescribe a different dosing schedule.
• if you have nervous system disorders, respiratory disorders, or you are more than 65 years old, your doctor may prescribe you a different dosing regimen.
• if you are on haemodialysis, (to remove waste products because of kidney failure), tell your doctor if you develop muscle pain and/or weakness.
• if you are pregnant, trying to become pregnant or are breast-feeding.
• if you develop signs such as persistent stomach pain, feeling sick and being sick contact your doctor immediately as these may be symptoms of acute pancreatitis (an inflamed pancreas).
• Before taking this medicine, tell your doctor if you have ever abused or been dependent on alcohol, prescription medicines or illegal drugs; it may mean you have a greater risk of becoming dependent on Gabapentin Capsules.
• are or have ever been addicted to opioids, alcohol, prescription medicines, or illegal drugs, or if you have ever had a history of struggling to control your alcohol or drug intake.
• have previously suffered from withdrawal symptoms such as agitation, anxiety, shaking or sweating, when you have stopped taking alcohol or drugs.
• feel you need to take more of Gabapentin Capsules to get the same level of symptom control, this may mean you are developing tolerance to the effects of this medicine or are becoming addicted to it. Speak to your prescriber who will discuss your treatment and may change your dose or switch you to an alternative medication.
• If you have myasthenia gravis (a disease causing muscle weakness) because this medicine may make your symptoms worse.

Cases of abuse and dependence have been reported for gabapentin from the post-marketing experience. Talk to your doctor if you have a history of abuse or dependence. A small number of people being treated with anti-epileptics such as gabapentin have had thoughts of harming or killing themselves. If at any time you have these thoughts, immediately contact your doctor.

Talk to your prescriber before taking this medicine if you:

• are or have ever been addicted to opioids, alcohol, prescription medicines, or illegal drugs, or if you have ever had a history of struggling to control your alcohol or drug intake.
• have previously suffered from withdrawal symptoms such as agitation, anxiety, shaking or sweating, when you have stopped taking alcohol or drugs.
• feel you need to take more of Gabapentin Capsules to get the same level of symptom control, this may mean you are developing tolerance to the effects of this medicine or are becoming addicted to it. Speak to your prescriber who will discuss your treatment and may change your dose or switch you to an alternative medication.

Taking this medicine regularly, particularly for a long time, can lead to physical dependence and addiction. Your prescriber should have explained how long you will be taking it for and, when it is appropriate to stop, how to do this safely. When your treatment is stopped, it is usually done gradually over a period which is specific to you and may occur over a period of weeks to months.

Physical dependence and addiction can cause withdrawal symptoms when you stop taking this medicine. Withdrawal symptoms can include:

• trouble sleeping, headache, nausea, feeling anxious, diarrhoea, flu-like symptoms, convulsions, nervousness, depression, thoughts of harming or killing yourself, pain, sweating, and dizziness.

  Some people may become dependent on Gabapentin Capsules (a need to keep taking the medicine).

  They may have withdrawal effects when they stop using Gabapentin Capsules or reduce the dose (see section 3, “How to take Gabapentin Capsules” and “If you stop taking Gabapentin Capsules”). If you have concerns that you may become dependent on Gabapentin Capsules, it is important that you consult your doctor.

  If you notice any of the following signs whilst taking Gabapentin Capsules, it could be a sign that you have become dependent.

  • You feel you need to take the medicine for longer than advised by your prescriber
  • You feel you need to take more than the recommended dose
  • You are using the medicine for reasons other than prescribed
  • You have made repeated, unsuccessful attempts to quit or control the use of the medicine
  • When you stop taking the medicine you feel unwell, and you feel better once taking the medicine again

If you notice any of these, speak to your doctor to discuss the best treatment pathway for you, including when it is appropriate to stop and how to do this safely.

Important information about potentially serious reactions

Serious skin rashes including Stevens-Johnson syndrome, toxic epidermal necrolysis and drug reaction with eosinophilia and systemic symptoms (DRESS) have been reported in association with gabapentin. Stop using gabapentin and seek medical attention immediately if you notice any of the symptoms related to these serious skin reactions described in section 4. Read the description of these symptoms in section 4 of this leaflet under ‘Contact your doctor immediately if you experience any of the following symptoms after taking this medicine as they can be serious’

Muscle weakness, tenderness or pain and particularly, if at the same time, you feel unwell or have a high temperature it may be caused by an abnormal muscle breakdown which can be life-threatening and lead to kidney problems. You may also experience discolouration of your urine, and a change in blood test results (notably blood creatine phosphokinase increased). If you experience any of these signs or symptoms, please contact your doctor immediately.

Other medicines and Gabapentin

Please tell your doctor or pharmacist if you are taking or have recently taken or might take any other medicines. In particular, tell your doctor (or pharmacist) if you are taking or have been recently taking any medicines for convulsions, sleeping disorders, depression, anxiety, or any other neurological or psychiatric problems.

Medicines containing opioids such as morphine

If you are taking any medicines containing opioids (such as morphine), please tell your doctor or pharmacist, as morphine may increase the effect of Gabapentin. In addition, combination of Gabapentin with opioids may cause symptoms like sleepiness, sedation, decrease in breathing, or death. Antacids for indigestion

If Gabapentin and antacids containing aluminium and magnesium are taken at the same time, absorption of Gabapentin from the stomach may be reduced. It is therefore recommended that Gabapentin is taken at the earliest two hours after taking an antacid.

Gabapentin

• is not expected to interact with other antiepileptic drugs or the oral contraceptive pill.
• may interfere with some laboratory tests, if you require a urine test tell your doctor or hospital what you are taking. Gabapentin with food

Gabapentin can be taken with or without food.

Gabapentin contain lactose monohydrate and sunset yellow

• These capsules contain lactose monohydrate. If you have been told by your doctor that you have an intolerance to some sugars, contact your doctor before taking this medicinal product.
• Gabapentin 400mg contain sunset yellow (E110) which may cause allergic reactions.

Pregnancy, breast-feeding and fertility

• If you are pregnant or think you may be pregnant, you must tell your doctor straight away and discuss possible risks the medicine you are taking might pose to your unborn baby.
• If you are planning to become pregnant you should discuss your treatment with your doctor or pharmacist as early as possible before you become pregnant.
• You should not stop your treatment without discussing this with your doctor.
• If you are breastfeeding or planning to breastfeed, ask your doctor or pharmacist for advice before taking this medicine. Pregnancy

Gabapentin can be used during the first trimester of pregnancy if needed.

If you plan to become pregnant or if you are pregnant or think you may be pregnant, talk to your doctor straight away. If you have become pregnant and you have epilepsy, it is important that you do not stop taking your medicine without first consulting your doctor, as this may worsen your illness. Worsening of your epilepsy may put you and your unborn child at risk.

In a study reviewing data from women in Nordic countries who took gabapentin in the first 3 months of pregnancy, there was no increased risk of birth defects or problems with the development of brain function (neurodevelopment disorders). However, babies of women who took gabapentin during pregnancy had an increased risk of low birth weight and preterm birth.

If used during pregnancy, gabapentin may lead to withdrawal symptoms in newborn infants.

This risk might be increased when gabapentin is taken together with opioid analgesics (drugs for treatment of severe pain). Contact your doctor immediately if you become pregnant, think you might be pregnant or are planning to become pregnant while taking Gabapentin. Do not suddenly discontinue taking this medicine as this may lead to a breakthrough seizure, which could have serious consequences for you and your baby. Breast-feeding

Gabapentin is passed on through breast milk. The effect on the baby is unknown; therefore, you should not breast-feed your baby unless told to by your doctor.

Fertility

Your prescriber will discuss with you how to gradually reduce your dose before stopping the medicine. It is important that you do not stop taking the medicine suddenly as you will be more likely to experience withdrawal symptoms. Your prescriber will ensure that your plan for stopping treatment is tailored to you and can be adapted according to your needs and experience of any withdrawal symptoms.

Gabapentinoids should only be used by those they are prescribed for. Do not give your medicine to anyone else. Taking higher doses or more frequent doses of gabapentinoids, may increase the risk of addiction. Overuse and misuse can lead to overdose and/or death.

There is no effect on fertility in animal studies.

Driving and using machines

Gabapentin may cause dizziness, drowsiness and tiredness. You should not drive, operate complex machinery or take part in other potentially hazardous activities until you know whether this medication affects your ability to perform these activities.

3. How to take Gabapentin

Always take your medicine exactly as your doctor has told you. Check with your doctor or pharmacist if you are not sure. Do not take more medicine than prescribed.

Your doctor will decide the dose that is right for you. Your prescriber should have discussed with you how long the course of gabapentin capsules will last. They will arrange a plan for stopping treatment. This will outline how to gradually reduce the dose and stop taking the medicine. Your prescriber will ensure that your plan for stopping treatment is tailored to you and can be adapted according to your needs and experience of any withdrawal symptoms.

Gabapentin Capsules are to be swallowed with plenty of water and can be taken with or without food

Dose for Peripheral Neuropathic pain:

• Adults

  Take the number of capsules or tablets as instructed by your doctor. Your doctor will usually built up your dose gradually. The starting dose will generally be between 300mg and 900mg each day. Thereafter, the dose may be increased as by your doctor up to a maximum of 3600mg each day and your doctor will tell you to take this in 3 separate doses - in the morning, in the afternoon and in the evening.

If you have kidney problems or are receiving haemodialysis

Your doctor may prescribe a different dosing schedule and/or dose if you have problems with your kidneys or are undergoing haemodialysis.

If you are an elderly patient (over 65 years of age)

You should take the normal dose of Gabapentin unless you have problems with your kidneys. Your doctor may prescribe a different dosing schedule and/or dose if you have problems with your kidneys.

If you have the impression that the effect of Gabapentin is too strong or too weak, talk to your doctor or pharmacist as soon as possible.

Dose for epilepsy:

• Adults and adolescents

  Take the number of capsules or tablets as instructed. Your doctor will usually build up your dose gradually. The starting dose is usually between 300 mg and 900 mg each day. The dose is then built up gradually each day in 3 divided doses – in the morning, at midday and in the evening. The maximum daily dose is 3600mg.

• Children aged 6 years and above

  The dose to be given to your child will be decided by your doctor and is calculated using your child’s weight. The treatment is started using a low dose, which is gradually increased over a period of approximately 3 days. The usual dose to control epilepsy is 25–35mg per kg per day. It is usually given in 3 divided doses each day, by taking the capsules in the morning, at midday and in the evening. Gabapentin should not be given to children under 6 years of age.

Method of administration

Gabapentin is for oral use. Always swallow the capsules or tablets with plenty of water.

Continue taking Neurontin until your doctor tells you to stop. If you forget to take a dose

Take it as soon as you remember unless it is nearly time for your next dose. Do not take two doses at the same time. If you take more Gabapentin than you should

Higher than recommended doses may result in an increase in side effects including loss of consciousness, dizziness, double vision, slurred speech, drowsiness and diarrhoea. Call your doctor or go to the nearest hospital emergency unit immediately if you take more Gabapentin than your doctor prescribed. Take along any capsules or tablets that you have not taken, together with the container and the label so that the hospital can easily tell what medicine you have taken.

If you stop taking Gabapentin

Do not suddenly stop taking this medicine or reduce your dose. If you want to stop taking this medicine or reduce your dose, discuss this with your prescriber first. They will tell you how to do this, usually by reducing the dose gradually so that any unpleasant withdrawal effects are kept to a minimum. If your treatment is stopped or your dose is reduced, it should be done gradually over a minimum of 1 week. Your prescriber will ensure that your plan for stopping a short or long-term treatment with Gabapentin or after reducing your dose, is tailored to you and can be adapted according to your needs and experience of any withdrawal symptoms.

Withdrawal symptoms such as: trouble sleeping, headache, nausea, feeling anxious, diarrhoea, flu-like symptoms, convulsions, nervousness, depression, thoughts of harming or killing yourself, pain, sweating, and dizziness.

These effects usually occur within 48 hours after stopping Gabapentin Capsules or reducing your dose. If you experience withdrawal effects, you should contact your doctor. If you have any further questions on the use of this medicine, ask your doctor or pharmacist.

4. Possible side effects

Like all medicines, Gabapentin Capsules can cause side effects, although not everybody gets them.

Tell your doctor immediately or go to the nearest hospital casualty department if you have any of the following serious side effects:

• Severe skin reaction that require immediate attention, Swelling of the lips and face, skin rash and redness, and/or hair loss (these may be symptoms of a serious allergic reaction).
• Persistent stomach pain, feeling sick and being sick as these may be symptoms of acute pancreatitis (an inflamed pancreas)
• Breathing problems, which if severe you may need emergency and intensive care to continue breathing normally
• Gabapentin may cause a serious or life-threatening allergic reaction that may affect your skin or other parts of your body such as liver or blood cells. You may or may not have a rash when you get this type of reaction. It may cause you to be hospitalized or to stop gabapentin.

Call your doctor right away if you have any of the following symptoms:

• Skin rash
• Hives
• Fever
• Swollen glands that do not go away
• Swelling of your lip and tongue
• Yellowing of your skin or of the whites of the eyes
• Unusual bruising or bleeding
• Severe fatigue or weakness
• Unexpected muscle pain
• Frequent infections

These symptoms may be the first signs of a serious reaction. A doctor should examine you to decide if you should continue taking gabapentin.

If you are on haemodialysis, tell your doctor if you develop muscle pain and/or weakness.

Stop using Gabapentin Capsules and seek medical attention immediately if you notice any of the following symptoms:

• Reddish non-elevated, target-like or circular patches on the trunk, often with central blisters, skin peeling, ulcers of mouth, throat, nose, genitals and eyes. These serious skin rashes can be preceded by fever and flu-like symptoms (Stevens-Johnson syndrome, toxic epidermal necrolysis).
• Widespread rash, high body temperature and enlarged lymph nodes (DRESS syndrome or drug hypersensitivity syndrome). If any of the following side effects gets worse or you are worried tell your doctor or pharmacist:

Very common: may affect more than 1 in 10 people:

• Viral infection.
• Feeling drowsy, dizziness, lack of coordination.
• Feeling tired, fever.

Common: may affect up to 1 in 10 people:

• Pneumonia, respiratory infections, urinary tract infection, inflammation of the ear or other infections.
• Low white blood cell counts.
• Anorexia, increased appetite.

• Anger towards others, confusion, mood changes, depression, anxiety, nervousness, difficulty with thinking.

  • Convulsions, jerky movements, difficulty with speaking, loss of memory, tremor, difficulty sleeping, headache, sensitive skin, decreased sensation (numbness), difficulty with coordination, unusual eye movement, increased, decreased or absent reflexes.
  • Blurred vision, double vision.
  • Vertigo.
  • High blood pressure, flushing or dilation of blood vessels.
  • Difficulty breathing, bronchitis, sore throat, cough, dry nose.
  • Vomiting (being sick), nausea (feeling sick), problems with teeth, inflamed gums, diarrhoea, stomach pain, indigestion, constipation, dry mouth or throat, flatulence.
  • Facial swelling, bruises, rash, itch, acne.
  • Joint pain, muscle pain, back pain, twitching.
  • Difficulties with erection (impotence).
  • Swelling in the legs and arms, difficulty with walking, weakness, pain, feeling unwell, flu-like symptoms.
  • Decrease in white blood cells, increase in weight.
  • Accidental injury, fracture, abrasion.

Additionally in clinical studies in children, aggressive behaviour and jerky movements were reported.

Uncommon: may affect up to 1 in 100 people:

• Difficulty swallowing.
• Allergic reactions such as hives.
• Decreased movement.
• Racing heartbeat.
• Swelling that may involve the face, trunk and limbs.
• Abnormal blood test results suggesting problems with the liver.
• Fall.
• Mental impairment.
• Increase in blood glucose levels (most often observed in patients with diabetes).
• Agitation (a state of chronic restlessness and unintentional and purposeless motions).

Rare: May affect up to 1 in 1,000 people:

• Trouble breathing, shallow breaths (respiratory depression)
• Loss of consciousness.
• Decrease in blood glucose levels (most often observed in patients with diabetes).

Not known: frequency cannot be estimated from the available data:

• Decreased platelets (blood clotting cells).
• Suicidal thoughts, Hallucinations.
• Problems with abnormal movements such as writhing, jerking movements and stiffness.
• Ringing in the ears.
• Yellowing of the skin and eyes (jaundice), Inflammation of the liver.
• Acute kidney failure, incontinence.
• Increased breast tissue, breast enlargement.
• Adverse events following the abrupt discontinuation of gabapentin (anxiety, difficulty sleeping, feeling sick, pain, sweating), chest pain.
• Breakdown of muscle fibres (rhabdomyolysis).
• Change in blood test results (creatine phosphokinase increased).
• Problems with sexual functioning including inability to achieve a sexual climax, delayed ejaculation.
• Low blood sodium level.
• Anaphylaxis (serious, potentially life-threatening allergic reaction including difficulty breathing, swelling of the lips, throat, and tongue, and hypotension requiring emergency treatment).
• Becoming dependent on Gabapentin Capsule (‘drug dependence’).
• Dependence and addiction (see section “How do I know if I am tolerant or addicted?”)
• Worsening of myasthenia gravis (a disease causing muscle weakness)

Drug Withdrawal - When you stop taking gabapentin capsules, you may experience drug withdrawal symptoms, which include:

• trouble sleeping, headache, nausea, feeling anxious, diarrhoea, flu-like symptoms, convulsions, nervousness, depression, thoughts of harming or killing yourself, pain, sweating, and dizziness.

How do I know if I am tolerant or addicted?

• If you notice any of the following signs whilst taking Gabapentin Capsule, it could be a sign that you have become addicted.
• You may feel the need to keep taking the medication for longer than your doctor recommended
• You feel you need to use more than the recommended dose
• You are using the medicine for reasons other than prescribed
• When you stop taking the medicine you feel unwell, and you feel better once taking the medicine again
• If you notice any of these signs, it is important you talk to your prescriber.

After stopping a short or long-term treatment with Gabapentin Capsules or after reducing your dose, you need to know that you may experience certain side effects, so-called withdrawal effects (see “If you stop taking Gabapentin Capsules”).

Reporting of side effects

If you get any side effects, talk to your doctor or pharmacist. This includes any possible side effects not listed in the leaflet. You can also report side effects directly via the Yellow card Scheme at: www.mhra.gov.uk/yellowcard or search for MHRA Yellow Card in the Google Play or Apple App Store. By reporting side effects you can help provide more information on the safety of this medicine.

5. How to store Gabapentin

Keep this medicine out of the sight and reach of children.

Do not store above 25°C. Store in the original package. Do not use after the expiry date, which is stated on the blister strip and carton. The expiry date refers to the last day of that month.

Medicines should not be disposed of via wastewater or household waste. Ask your pharmacist how to dispose of medicines no longer required. These measures will help to protect the environment.

6. Contents of the pack and other information

What Gabapentin contains

• Each capsule contains 100mg, 300mg or 400mg of the active substance gabapentin.
• The other ingredients are maize starch, lactose monohydrate, and talc.
• The capsules are made from gelatin and titanium oxide. The 300mg capsule also contains yellow iron oxide (E172) and quinoline yellow (E104). The 400mg capsule also contains sunset yellow (E110).
• The marking ink contains Shellac (E904), Dehydrated alcohol, Isopropyl alcohol, Butyl Alcohol, Propylene glycol (E1520), strong ammonia solution (E527), Black Iron oxide (E172) and Potassium Hydroxide (E525).

What Gabapentin look like and contents of the pack

The 100mg capsule is a hard white capsule marked with ‘GABA100’.

The 300mg capsule is a hard yellow capsule marked with ‘GABA 300’.

The 400mg capsule is a hard orange capsule marked with ‘GABA400’.

They are available in packs of 90 or 100 capsules in blister strips of 10 capsules.

Marketing Authorisation Holder and Manufacturer

Crescent Pharma Ltd., Key House,

Sarum Hill, Basingstoke, RG21 8SR, UK.

This leaflet was last revised in January 2026.

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