Get emergency medical help if you have signs of an allergic reaction to gabapentin: hives; difficult breathing; swelling of your face, lips, tongue, or throat.
Seek medical treatment if you have a skin rash with symptoms of a serious allergic reaction that can affect other parts of your body, including: fever, dark urine, blood in your urine, swollen glands, sore throat, extreme weakness or tiredness, unusual bruising or bleeding, muscle pain, or jaundice (yellowing of the skin or eyes).
Report any new or worsening symptoms to your doctor, such as: mood or behavior changes, anxiety, depression, or if you feel agitated, hostile, restless, hyperactive (mentally or physically), or have thoughts about suicide or hurting yourself.
Dizziness and somnolence are the most frequent side effects. Fatigue, ataxia, peripheral edema (swelling of extremities), and nystagmus are also common. A 2017 meta-analysis found that gabapentin also increased the risk of difficulties in mentation and visual disturbances as compared to a placebo.
Gabapentin is associated with a weight gain of 2.2 kg (4.9 lb) after 1.5 months of use. Case studies indicate that it may cause anorgasmia and erectile dysfunction, as well as myoclonus that disappear after discontinuing gabapentin or replacing it with other medication.
Fever, swollen glands that do not go away, eyes or skin turning yellow, unusual bruises or bleeding, unexpected muscle pain or weakness, rash, long-lasting stomach pain which may indicate an inflamed pancreas, hallucinations, anaphylaxis, respiratory depression, and increased suicidal ideation are rare but serious side effects.
Call your doctor at once if you have:
- increased seizures;
- severe weakness or tiredness;
- upper stomach pain;
- chest pain, new or worsening cough with fever, trouble breathing;
- severe tingling or numbness;
- rapid back and forth movement of your eyes;
- kidney problems–little or no urination, painful or difficult urination, swelling in your feet or ankles, feeling tired or short of breath; or
- severe skin reaction–fever, sore throat, swelling in your face or tongue, burning in your eyes, skin pain followed by a red or purple skin rash that spreads (especially in the face or upper body) and causes blistering and peeling.
Some side effects are more likely in children taking gabapentin. Contact your doctor if the child taking this medication has any of the following side effects:
- changes in behavior;
- memory problems;
- trouble concentrating; or
- acting restless, hostile, or aggressive.
Common gabapentin side effects may include:
- dizziness, drowsiness; or
- headache.
This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.
Like all medicines, gabapentin can cause side effects, although not everyone gets them.
Common side effects
These common side effects of gabapentin may happen in more than 1 in 100 people. They’re usually mild and go away by themselves.
There are things you can do to help cope with them:Feeling sleepy, tired or dizzy
- Feeling sick (nausea)
- Being sick (vomiting)
- Diarrhoea
- Mood changes
- Swollen arms and legs
- Blurred vision
- Dry mouth
- Difficulty getting an erection
- Weight gain
- Memory problems
- Headaches
- Getting more infections than usual
Gabapentin Serious side effects
Very few people taking gabapentin have serious problems.
Call a doctor or call 111 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
- a high temperature, swollen glands that do not go away, your eyes or skin turn yellow (this may be less obvious on brown or black skin), unusual bruises or bleeding, severe tiredness or weakness, unexpected muscle pain or weakness, with or without a rash – these may be symptoms of a serious reaction
- long-lasting stomach pain, feeling sick or being sick – these may be warning signs of an inflamed pancreas
- muscle pain or weakness and you’re having dialysis treatment because of kidney failure
- seeing things that are not there (hallucinations)
Serious allergic reaction
In rare cases, it’s possible to have a serious allergic reaction (anaphylaxis) to gabapentin.
Immediate action required:Call 999 now if:
- your lips, mouth, throat or tongue suddenly become swollen
- you’re breathing very fast or struggling to breathe (you may become very wheezy or feel like you’re choking or gasping for air)
- your throat feels tight or you’re struggling to swallow
- your skin, tongue or lips turn blue, grey or pale (if you have black or brown skin, this may be easier to see on the palms of your hands or soles of your feet)
- you suddenly become very confused, drowsy or dizzy
- someone faints and cannot be woken up
- a child is limp, floppy or not responding like they normally do (their head may fall to the side, backwards or forwards, or they may find it difficult to lift their head or focus on your face)
You or the person who’s unwell may also have a rash that’s swollen, raised, itchy, blistered or peeling.
These can be signs of a serious allergic reaction and may need immediate treatment in hospital.
Information:
Do not drive yourself to A&E.
The person you speak to at 999 will give you advice about what to do.
Long-term side effects
- Some people can become addicted to gabapentin. If this happens, you’ll have withdrawal symptoms after you stop taking the medicine.
- When you stop taking gabapentin, you’ll need to reduce your dose gradually to avoid withdrawal symptoms. Do not stop taking gabapentin without talking to your doctor.
- Talk to your doctor if you’re concerned about becoming physically dependent on gabapentin.
Other side effects
These are not all the side effects of gabapentin. For a full list, see the leaflet inside your medicines packet.
Gabapentin (Neurontin) is one of the most commonly used medications in the U.S. It’s FDA approved to treat seizures and nerve pain from shingles (postherpetic neuralgia). It also has several off-label uses.
Common Side Effects of Gabapentin
- Drowsiness: Feeling unusually tired or sleepy is one of the most common side effects.
- Dizziness: You may feel light-headed or off-balance.
- Fatigue: General tiredness or lack of energy.
- Coordination Problems: Difficulty with coordination, unsteady movements, or clumsiness.
- Blurred Vision: Vision may become less clear.
- Tremors: Shaking or trembling, especially in the hands.
- Nausea and Vomiting: Some people experience an upset stomach.
- Swelling (Edema): Swelling of the hands, feet, or ankles.
- Weight Gain: Some people notice an increase in weight, especially with prolonged use.
- Memory Issues: Difficulty concentrating, remembering things, or experiencing mental fog.
- Dry Mouth: A dry feeling in the mouth or throat.
- Headache: Mild to moderate headaches
Less Common but Serious Side Effects
- Mood Changes: Including anxiety, irritability, depression, or agitation.
- Suicidal Thoughts: Gabapentin has a rare risk of causing suicidal thoughts or behavior. This is especially concerning if there’s a history of mental health issues.
- Severe Allergic Reactions: Symptoms can include rash, itching, swelling (especially of the face or throat), severe dizziness, or trouble breathing. This requires immediate medical attention.
- Difficulty Breathing: Breathing problems may occur, particularly in people with respiratory conditions.
- Muscle Weakness: Unusual muscle weakness or pain.
- Unusual Eye Movements: Jerky eye movements (nystagmus) can occur, which may affect vision.
- Increased Seizure Frequency: In rare cases, people may experience an increase in the frequency of seizures instead of relief.
- Low Blood Sodium Levels (Hyponatremia): Symptoms can include confusion, severe drowsiness, and weakness.
Psychological Side Effects:
- Mood Changes:
- Depression, anxiety, or mood swings.
- Behavioral Changes:
- Agitation, irritability, or hyperactivity.
- Suicidal Thoughts:
- Increased risk of suicidal ideation, particularly in younger individuals.
Gastrointestinal Side Effects:
- Nausea and Vomiting:
- Feeling sick or actually being sick.
- Diarrhea or Constipation:
- Changes in bowel movements.
- Dry Mouth:
- Decreased saliva production, leading to a dry feeling in the mouth.
Serious Side Effects:
- Allergic Reactions:
- Symptoms include rash, itching, swelling, severe dizziness, and trouble breathing.
- Respiratory Depression:
- Slowed or difficult breathing, particularly dangerous if taken with other CNS depressants.
- Severe Skin Reactions:
- Conditions like Stevens-Johnson syndrome, characterized by painful rashes and blisters.
- Pancreatitis:
- Inflammation of the pancreas, leading to severe abdominal pain, nausea, and vomiting.
- Kidney Problems:
- Changes in urine output or color, swelling in the legs, and feeling tired.
- Changes in urine output or color, swelling in the legs, and feeling tired.
Long-Term Side Effects:
- Dependency and Withdrawal:
- Although not common, there is potential for dependency with prolonged use. Withdrawal symptoms can include anxiety, insomnia, nausea, pain, and sweating.
- Chronic Fatigue:
- Persistent tiredness that does not improve with rest.
- Cognitive Impairment:
- Long-term use can potentially lead to difficulties with concentration and memory.