Gabapentin Side Effects

Like all medicines, gabapentin can cause side effects, although not everyone gets them.

Common side effects of Gabapentin

These common side effects may happen in more than 1 in 100 people.

They’re usually mild and go away by themselves.

Keep taking the medicine, but talk to your doctor if these side effects bother you or don’t go away:

      • feeling sleepy, tired or dizzy
      • feeling sick (nausea)
      • being sick (vomiting) and diarrhoea
      • getting more infections than usual
      • mood changes
      • swollen arms and legs
      • blurred vision
      • dry mouth
      • difficulties for men getting an erection
      • weight gain – gabapentin can make you feel hungry
      • memory problems
      • headaches

Serious side effects

Very few people taking gabapentin have serious problems.

Call a doctor straight away if you have a serious side effect, including:

  • thoughts of harming or killing yourself – a small number of people taking gabapentin have had suicidal thoughts, which can happen after only a week of treatment
  • yellowing of your skin or whites of your eyes – these may be warning signs of jaundice
  • unusual bruises or bleeding – these may be warning signs of a blood disorder
  • long-lasting stomach pain, feeling sick or vomiting – these may be warning signs of an inflamed pancreas
  • muscle pain or weakness and you’re having dialysis treatment because of kidney failure
  • hallucinations

Serious allergic reaction

In rare cases, it’s possible to have a serious allergic reaction (anaphylaxis) to gabapentin.

Immediate action required:Call 999 or go to A&E now if:
  • you get a skin rash that may include itchy, red, swollen, blistered or peeling skin
  • you’re wheezing
  • you get tightness in the chest or throat
  • you have trouble breathing or talking
  • your mouth, face, lips, tongue or throat start swelling

You could be having a serious allergic reaction and may need immediate treatment in hospital.

These are not all the side effects of gabapentin. For a full list, see the leaflet inside your medicines packet.

How to cope with side effects

What to do about:

  • feeling sleepy, tired or dizzy – as your body gets used to gabapentin, these side effects should wear off. If they don’t wear off within a week or two, your doctor may reduce your dose or increase it more slowly. If that doesn’t work, you may need to switch to a different medicine.
  • feeling sick (nausea) – take gabapentin with or after a meal or snack. It may also help if you don’t eat rich or spicy food.
  • being sick (vomiting) and diarrhoea – drink plenty of water or other fluids to avoid dehydration. Take small sips if you feel sick. Signs of dehydration include peeing less than usual or having dark strong-smelling pee. Do not take any other medicines to treat diarrhoea or vomiting without speaking to a pharmacist or doctor.
  • mood changes – if you feel this medicine is causing mood changes, talk to your doctor. You may be able to change to an alternative medicine.
  • swollen arms and legs – try sitting with your feet raised and try not to stand for a long time. Gently exercising your arms might help. Talk to your doctor if this doesn’t get better.
  • blurred vision – avoid driving or using tools or machines while this is happening. If it lasts for more than a day or two, speak to your doctor as they may need to change your treatment.
  • a dry mouth – chew sugar-free gum or suck sugar-free sweets.
  • difficulties for men getting an erection – speak to your doctor, as they may be able to change your medicine or offer other treatments that might help with this problem.
  • weight gain – gabapentin can make you hungrier, so it can be quite a challenge to stop yourself putting on weight. Try to eat a healthy, balanced diet without increasing your portion sizes. Do not snack on foods that contain a lot of calories, such as crisps, cakes, biscuits and sweets. If you feel hungry between meals, eat fruit and vegetables and low-calorie foods. Regular exercise will also help to keep your weight stable.
  • memory problems – if you’re having problems with your memory, speak to your doctor. They may want to try a different medicine.
  • headaches – make sure you rest and drink plenty of fluids. Do not drink too much alcohol. Ask your pharmacist to recommend a painkiller. Headaches should usually go away after the first week of taking gabapentin. Talk to your doctor if they last longer than a week or are severe.

7. Pregnancy and breastfeeding

    • Gabapentin is not generally recommended in pregnancy.
    • There’s no firm evidence that it’s harmful to an unborn baby, but for safety pregnant women are usually advised to take it only if the benefits of the medicine outweigh the potential harm.
    • If you take gabapentin for epilepsy and become pregnant, do not stop the medicine without talking to your doctor first.
    • It’s very important that epilepsy is treated during pregnancy as seizures can harm you and your unborn baby.
    • If you’re trying to get pregnant or have become pregnant, you’re routinely recommended to take at least 400mcg of a vitamin called folic acid everyday. It helps the unborn baby grow normally.
    • Pregnant women who take gabapentin are recommended to take a higher dose of folic acid.
    • Your doctor might prescribe a high dose of 5mg a day for you to take during the first 12 weeks of pregnancy.
    • If you take gabapentin around the time of giving birth, your baby may need extra monitoring for a few days after they’re born because they may have gabapentin withdrawal symptoms.
    • For more information about how gabapentin can affect you and your baby during pregnancy, read this leaflet on the Best Use of Medicines in Pregnancy (BUMPS) website.

Gabapentin and breastfeeding

    • Usually, you can breastfeed while taking gabapentin.
    • Check with your doctor first though if your baby is premature or has kidney problems.

How to cope with side effects

What to do about:

    • feeling sleepy, tired or dizzy – as your body gets used to gabapentin, these side effects should wear off. If they don’t wear off within a week or two, your doctor may reduce your dose or increase it more slowly. If that doesn’t work, you may need to switch to a different medicine.
    • feeling sick (nausea) – take gabapentin with or after a meal or snack. It may also help if you don’t eat rich or spicy food.
    • being sick (vomiting) and diarrhoea – drink plenty of water or other fluids to avoid dehydration. Take small sips if you feel sick. Signs of dehydration include peeing less than usual or having dark strong-smelling pee. Do not take any other medicines to treat diarrhoea or vomiting without speaking to a pharmacist or doctor.
    • mood changes – if you feel this medicine is causing mood changes, talk to your doctor. You may be able to change to an alternative medicine.
    • swollen arms and legs – try sitting with your feet raised and try not to stand for a long time. Gently exercising your arms might help. Talk to your doctor if this doesn’t get better.
    • blurred vision – avoid driving or using tools or machines while this is happening. If it lasts for more than a day or two, speak to your doctor as they may need to change your treatment.
    • a dry mouth – chew sugar-free gum or suck sugar-free sweets.
    • difficulties for men getting an erection – speak to your doctor, as they may be able to change your medicine or offer other treatments that might help with this problem.
    • weight gain – gabapentin can make you hungrier, so it can be quite a challenge to stop yourself putting on weight. Try to eat a healthy, balanced diet without increasing your portion sizes. Do not snack on foods that contain a lot of calories, such as crisps, cakes, biscuits and sweets. If you feel hungry between meals, eat fruit and vegetables and low-calorie foods. Regular exercise will also help to keep your weight stable.
    • memory problems – if you’re having problems with your memory, speak to your doctor. They may want to try a different medicine.
    • headaches – make sure you rest and drink plenty of fluids. Do not drink too much alcohol. Ask your pharmacist to recommend a painkiller. Headaches should usually go away after the first week of taking gabapentin. Talk to your doctor if they last longer than a week or are severe.

Along 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 gabapentin. 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 gabapentin side-effects
What can I do if I experience this?
Feeling sleepy, tired, unsteady or dizzy; blurred vision and other eyesight problems Do not drive or use tools or machines
Headache Ask your pharmacist to recommend a suitable painkiller
Feeling or being sick, indigestion, stomach ache Stick to simple foods – avoid rich or spicy meals
Diarrhoea Drink plenty of water to replace the lost fluids
Constipation Try to eat a well-balanced diet and drink several glasses of water each day
Dry mouth Try chewing sugar-free gum or sucking sugar-free sweets
Infections, flu-like symptoms, increased appetite, flushing,
increased blood pressure, changes in weight, changes in emotions or mood, fits, movement difficulties, feeling shaky, difficulties sleeping, breathing difficulties, cough, gum changes, bruises, muscle or joint pains, impotence, and swollen feet or ankles
If any of these become troublesome, speak with your doctor for advice

Important: gabapentin has been associated with a number of unwanted effects which affect the blood, pancreas and liver. Although these occur less commonly than the side-effects listed above, you must let your doctor know straightaway if you notice any of the following as they could be serious:

  • Persistent stomach pain with sickness (these could be symptoms of an inflamed pancreas).
  • A skin rash, or any swelling of your mouth or face (these could be symptoms of an allergic reaction).
  • Any yellowing of your skin or of the whites of your eyes (these could be symptoms of jaundice).
  • Any unusual bruising or bleeding (these could be symptoms of a blood disorder).

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