Gabapentin Side Effects: Common and Severe Side Effects

Gabapentin Side Effects – Overview

Gabapentin is a well-established anticonvulsant drug. It reduces abnormal excitement in the nerve and brain cells by lowering their activation. As a result, gabapentin effectively treats seizures in people with epilepsy and relieves neuropathic pain, a type of pain produced by abnormal nerve conduction. Post-herpetic neuralgia is a type of neuropathic pain produced by shingles infection and is one of the cases where gabapentin can be used. (1, 2)

Gabapentin enacarbil, as an extended-release tablet, is approved for treating moderate-to-severe primary Restless Legs Syndrome (RLS). This neurological disorder causes an uncontrollable urge to move the legs, usually because of an uncomfortable sensation. (2, 3)

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Like any other drug, gabapentin may cause side effects. However, some of them, such as hypersensitivity or suicidal thoughts, although rare, can be life-threatening and even fatal. Recognizing the signs of life-threatening side effects can save your life. (1, 3)

This article explains the most common and serious side effects associated with gabapentin use. Keep reading to learn about when you need to call your doctor and why shouldn’t you stop taking gabapentin on your own when treating epilepsy.

What Are Gabapentin’s Possible Side Effects?

Gabapentin’s Possible Side Effects

The most common side effects of gabapentin are the following:

Fever;
Viral infection;
Nausea and vomiting;
Feeling tired;
Feeling drowsy;
Difficulty with speaking;
Movement problems: lack of coordination, difficulty with coordination, tremor, jerky movements;
Eye problems: double vision, unusual eye movement. (1)

Headache, sleepiness, and dizziness are the most common side effects of gabapentin’s extended-release formulation. These side effects occur in more than 10% of people who take the medication, and they are at least twice as likely to occur in people taking gabapentin than in people taking a placebo. (3)

Nausea, dry mouth, fatigue, irritability, feeling abnormal, vertigo, or depression are side effects that may occur in less than 10% of people who take gabapentin. These side effects are less common than headache, sleepiness, and dizziness, but they can still be bothersome.

In some cases, following the United Kingdom National Health Service recommendations may help with relief from gabapentin side effects: (4)

Nausea and vomiting – Avoid rich or spicy food, and take gabapentin with or after a meal. Take small sips of fluids to keep you hydrated. Don’t use drugs to treat vomiting without consulting your doctor.

Diarrhea – Drink plenty of water to avoid dehydration. If you notice you pee less, have dark urine, or if it has a strong smell, you might be dehydrated. Therefore, it is important to keep adequately hydrated.

Dry mouth – Use sugar-free chewing gum or sweets.

Headache – Usually, the headache is gone a week after the treatment is initiated. Drink water or other fluids and rest. However, tell your doctor if you have severe headaches or they last more than a week.

Blurred vision – Avoid driving or using heavy machinery. Tell your doctor if your blurred vision does not disappear in a few days.

Tell your doctor if these or other adverse events appear, bother you, and don’t go away. Your doctor will give you appropriate medical advice.

Warning And Precautions When Using Gabapentin

Some side effects require precautions because they are severe, life-threatening, or even fatal. (1, 3)

Multiorgan Hypersensitivity

Multiorgan hypersensitivity is a rare side effect caused by some medications, such as gabapentin, lamotrigine, or carbamazepine. Also known as Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS), it affects several organs simultaneously and can be life-threatening or even fatal, so early signs detection is crucial. (1, 3, 5)

Fever, rash, and/or swollen, painful, or tender lymph nodes in the neck, armpit, or groin (lymphadenopathy) are typical symptoms. It involves the liver, kidney, or heart, which can cause yellow eyes or skin, bruising, unusual bleeding, feeling weak or pain in muscles, and inflammation of the kidney and heart muscle. An increased level of white blood cells than normal (eosinophilia) is often present. (1, 3, 6)

Fever or lymphadenopathy appears first, so if you have it, even without a rash, call your doctor immediately. If there is no other cause for these symptoms, your doctor will discontinue gabapentin. (1, 3)

Anaphylaxis And Angioedema

Gabapentin can cause serious and life-threatening allergic reactions that can appear at any time. Difficult breathing, trouble swallowing due to swollen lips, throat, and tongue, or decreased blood pressure are signs that require immediate medical care. If you notice any of the symptoms mentioned above, stop taking your drug and seek urgent medical care. (1, 3)

Suicidal Thoughts

Gabapentin can cause you to have abnormal or suicidal thoughts. Some patients may feel sad, nervous, or restless and can easily get upset, have suicidal thoughts, or attempt to commit suicide. Depression can also occur or, if present, worsen. Panic attacks, aggressive behavior, anger or violence, and an extreme increase in activity and talking are other symptoms. (1, 3)

Your doctor will monitor you; however, you can also pay attention to sudden changes in mood, behaviors, thoughts, or feelings. Keep regularly all scheduled visits and tell your doctor any changes you notice.

Suicidal thoughts can be associated with your medication, but other reasons can cause them too. So, talk to your doctor first before you stop taking your medication. (1, 3)

Changes In Behavior And Thinking In Children

In children 3 to 12 years of age, gabapentin can be associated with aggressive behavior, hyperactivity, emotional changes, problems with concentration, or changes in school performance. Carefully monitor how your child reacts to the therapy and pay attention if such events occur. Talk to the doctor and ask for medical advice. (1, 3)

Driving Impairment, Somnolence/Sedation, And Dizziness

At the beginning of gabapentin treatment, you may experience clumsiness, vision changes, dizziness, unsteadiness, sleepiness, or problems with thinking. In controlled epilepsy trials, 19% of the patients reported somnolence and 17% dizziness. Those who had post-herpetic neuralgia reported the same symptoms at a higher rate. (1, 3)

It is unknown how long this condition can last, so don’t drive until you find out how you react to the medication and if you can drive or operate heavy machinery. Consult your doctor if these symptoms bother you and limit your daily life. If needed, your doctor may discontinue gabapentin therapy. (1, 3, 6)

Risk Of Seizures

Increased seizure frequency may occur if gabapentin is abruptly discontinued in patients with seizure disorders. It may worsen your epilepsy and cause prolonged seizures (status epilepticus). Different studies reported that the incidence of status epilepticus was not higher than 1.5%; however, there is insufficient data to estimate the frequency. In case you notice increased seizure frequency, talk to your doctor. (1,3)

Call your doctor for medical advice about any adverse event that appears. In addition, you may report side effects to FDA at 1-800-FDA-1088.

Other Advice You Should Know About Gabapentin

When using gabapentin, keep in mind the following:

Gabapentin usage with morphine (drug interactions) – gabapentin interacts with morphine, where morphine increases gabapentin concentration. As a result, this interaction can cause slowed breathing. If you start to notice that you have trouble breathing or have a pale or blue mouth, fingernails, or skin, call 911 and seek medical help right away.

Pregnancy and breast-feeding – Tell your doctor if you plan on getting pregnant or are pregnant, as using this medication during pregnancy may cause serious birth defects to the unborn baby. Additionally, this medication can pass into breast milk and may harm the nursing baby. You should not breastfeed while taking this medication. Talk to your doctor about the risks and benefits of taking gabapentin during pregnancy.

Talk to your doctor – It is worth telling your doctor if you have any of the following medical problems:

Diabetes;
Kidney problems;
Severe kidney problems requiring hemodialysis;
Depression;
Mood or behavioral problems.

Additionally, let your doctor know about any medications or supplements you may be taking.

Don’t drink alcohol – avoid using alcohol or any substance that makes you dizzy or sleepy. Such consumption may worsen your sleepiness and dizziness.

Symptoms Of Overdose

If you took more than the dose your doctor prescribed, you might get overdosed. In such a case, the following symptoms may appear:

Double vision,
Slurred speech,
Drowsiness, and
Diarrhea.

If it happens to you, call the poison control helpline at 1-800-222-1222. The information is also available online at https://www.poisonhelp.org/help. In case of seizure or trouble with breathing, call 911 immediately. (1-3)

Gabapentin Misuse And Abuse Can Be Fatal

Gabapentin can put you at risk of addiction, misuse, or abuse. Improper use of this medication can lead to serious complications and unwanted side effects.

After 20 years of usage, some studies have shown gabapentin abuse or misuse. It happened for recreational purposes in combination with opioids, benzodiazepines, or psychedelics, as self-medication, or used in higher doses than recommended in those with prescription. (7) Gabapentin abuse can lead to substance dependence and intoxication. (8)

In cases of abrupt cessation of gabapentin, withdrawal symptoms like anxiety, agitation, fatigue, restlessness, dizziness, sensitivity to light, sweating, irregular heartbeat, or others may occur. (9)

Gabapentin abuse or misuse can be fatal. According to the Centers for Disease Control and Prevention, in 2019-20, half (52.3%) of gabapentin-involved deaths were due to overdose. The overdose death rate from the illegal use of opioids with gabapentin raised to 69.2% in the last quarter of 2020. (10)

Gabapentin’s Recommended Dosage

Gabapentin’s daily dosage depends on the disease and the patient’s age. This drug is available as an oral solution (50 mg/ml), capsules (100 mg, 300 mg, and 400 mg), or tablets (600 mg and 800 mg) that make the dose titration easy.

Epilepsy With Partial Onset Seizures

The starting daily dose in patients 12 years of age and older is 900 mg, divided into three doses. The daily dose can be increased by up to 1.800 mg/daily.

In patients 3 to 11 years of age, the starting daily dose is 10 to 15 mg/kg/day, divided into three equal doses. The dose increase depends on the age, so the recommended dose can be up to 40 mg/kg/day, given in three divided doses, and can be achieved in 3 days increasing step by step. (1, 3)

Postherpetic Neuralgia

The initial dose of gabapentin is 300 mg as a single dose and can be increased to 1.800 mg/day by adding 300 mg daily, day by day. Your doctor will divide the daily dose into 2 or 3 single doses. (1) If your doctor prescribes an extended-release formulation, you will take gabapentin twice daily. (3)

Restless Leg Syndrome Treatment

The recommended dose is 600 mg once daily and should be taken every day at 5 p.m. If you miss the dose, wait till the next day at the same time to take the next dose. (3)

Take note that you cannot interchange extended-release formulation with other gabapentin products. (3) Any therapy change should be done by your healthcare provider.

Final Thoughts

Gabapentin is a well-established medication for epilepsy treatment, for pain relief in post-herpetic neuralgia or RLS. When taken as recommended, gabapentin has an acceptable safety profile with well-known side effects.

Take your gabapentin dose as recommended, and be aware of the possible side effects that might appear. Even if some adverse events look mild, talk to your doctor and report it to FDA.

If anaphylaxis, multi-organ hypersensitivity, or suicidal thoughts symptoms occur, the treatment should be discontinued. In such cases, call your doctor right away to get advice on what to do.

Gabapentin can effectively help you to control seizures, relieve pain, or release from RLS. Use it as recommended to treat your disease safely.

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Gabapentin Side Effects: Common and Severe Side Effects of Gabapentin