13 Gabapentin Side Effects You Should Know About

GoodRx Health

Gabapentin (Neurontin) isFDA approved to treat certain types of seizures. It's also approved to treat nerve pain from shingles (postherpetic neuralgia). Gabapentin is also available as extended-release (ER) tabletsHorizant and Gralise. These ER forms are approved to treat postherpetic neuralgia. Horizant is also approved to treatrestless leg syndrome.

Gabapentin is also used off-label to treat conditions such as anxiety and nerve pain from diabetes. It may also be used to treat alcohol use disorder.

Though gabapentin has many potential uses, it can cause side effects too. Knowing about gabapentin side effects in advance can help you manage them if they happen to you.

Gabapentin side effects at a glance

Gabapentin side effects are usually mild, and they may be less common with gabapentin ER forms. Examples of mild side effects that can happen include:

• Vertigo (dizziness)

• Feeling fatigued or sleepy

• Fluid retention

• Trouble balancing or controlling movement

• Diarrhea or constipation

• Nausea and vomiting

• Brain fog

• Headache

• Weight gain

• Dry mouth

• Blurry or double vision

• Unusual eye movements

• Sexual problems, such as decreased sex drive (libido) or erectile dysfunction

• Flu-like symptoms in kids

Though rare, serious gabapentin side effects can also happen. Examples include:

• Mood or behavior changes in children

• Withdrawal symptoms, such as seizures, if stopped abruptly

• Suicidal thoughts or behaviors

• Slowed breathing when used with other medications that can affect breathing

• Severe allergic reactions, such as Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS) syndrome

1. Dizziness

Dizziness is the No. 1 side effect of gabapentin. In studies, almost 30% of people taking gabapentin for postherpetic neuralgia, and over 15% of people taking it for seizures, experienced dizziness. Dizziness is similarly common with Horizant. But it may be slightly less likely with Gralise.

Along with causing dizziness, gabapentin can worsen your coordination. This can increase your risk of falls, which is especially dangerous for older adults. If you're just starting to take gabapentin or your dose has increased, avoid driving or doing any activity that requires alertness. Once you see how gabapentin affects you, you and your prescriber can decide if it's safe to resume these activities.

Dizziness from gabapentin may improve over time. But if you have dizziness that affects your day-to-day life, or is causing falls, let your healthcare team know. They may recommend a lower dose of gabapentin or another medication altogether.

2. Tiredness

Taking gabapentin can make you sleepy. According to studies, about 20% of people taking gabapentin experience drowsiness or fatigue. It may be even more likely, affecting 20% to 30% of people, with Horizant. However, tiredness is less common with Gralise, occurring in about 5% of people taking it.

As with dizziness, tiredness can affect your ability to perform some activities. And taking gabapentin with other medications or substances that cause tiredness can worsen these effects. Examples include:

• Opioids, such as oxycodone (Roxicodone, OxyContin)

• Benzodiazepines, such as alprazolam (Xanax)

• "Z-drugs," such as zolpidem (Ambien, Edluar, and ZolpiMist)

• Antidepressants, such as trazodone

• Benadryl (diphenhydramine)

• Muscle relaxers, such as cyclobenzaprine (Amrix)

Always talk to your prescriber or pharmacist before taking gabapentin; they can check for interactions with other medications and substances. To limit tiredness from gabapentin, work with your prescriber to find the lowest dose that works for you. And if your tiredness doesn't improve or is affecting your daily life, let them know.

3. Swollen arms and legs

Gabapentin is a common medication-related cause of peripheral edema. This is when you experience swollen tissues in the body, often in the arms and legs.

Up to 8% of people report edema with gabapentin clinical studies. But it's more likely to occur in older adults. It's also more likely with higher gabapentin dosages (greater than 1,800 mg).

Often, edema from gabapentin is mild and doesn't cause serious issues. But for people with heart conditions, it can put excess stress on the heart. It can also be a problem for people with kidney or liver problems. So if you experience symptoms of edema, such as unusual swelling, let your prescriber know. And if you experience painful swelling that's warm to the touch or red, this may be a sign that you have a blood clot. Blood clots aren't caused by gabapentin and can be serious. Seek medical attention right away if you experience this.

4. Weight gain

Although it's uncommon, edema from gabapentin may lead to weight gain. If you experience edema or weight gain while taking gabapentin, let your prescriber know, but don't stop taking the medication until you speak with them.

Your prescriber may want to know if you've changed your diet, reduced your physical activity, or started taking other medications that could also cause edema or weight gain. If gabapentin is determined to be the cause, your prescriber may recommend a lower gabapentin dose or that you stop taking the medication altogether. If this isn't possible, they may recommend that you take medication to decrease edema, like a diuretic.

5. Blurred vision and other eye problems

Gabapentin may cause issues with your eyes, such as blurred or double vision. Another eye problem reported by 8% of people taking IR gabapentin for seizures is nystagmus (rapid eye movements that you can't control).

In general, vision problems are less commonly reported with Gralise than they are with IR gabapentin or Horizant. But if you're having vision problems, keep in mind that this can affect your ability to perform daily activities. This is why it's important to reach out to your prescriber if you have any changes in your vision. They may refer you to an eye specialist to determine if gabapentin is the cause.

6. Mood changes in children

In studies of children ages 3 to 12 years old, gabapentin was found to cause mood changes in some participants. These changes included:

• Mood swings

• Aggressive behavior

• Trouble concentrating

• Lowered ability to perform at school

• Restlessness and hyperactivity

While these side effects are not extremely common, they do occur. For example, up to 8% of children between 3 to 12 years old may experience aggressive behavior, such as hostility, when taking gabapentin. So, if your child is taking gabapentin and you notice any changes in their mood or behavior, speak to their healthcare team immediately.

7. Severe allergic reactions

Allergic reactions aren't considered to be the same as a medication side effect. But it's worth discussing because some allergic reactions are severe. In fact, the manufacturers of gabapentin include a warning for rare but serious allergic reactions in the product information. This may include angioedema or anaphylaxis, which can occur at any point during treatment.

Angioedema involves swelling that usually occurs in the face, mouth, or throat. Anaphylaxis is an allergic reaction involving the whole body. Often, this shows up as hives, itching, or swelling. More serious symptoms may include difficulty breathing, a fast heartbeat, and confusion.

Gabapentin can also cause another type of allergic reaction called DRESS syndrome. It usually starts with a fever, rash, and swelling of the lymph nodes. But it can progress and cause damage to major organs, like the liver, kidneys, or heart.

Angioedema, anaphylaxis, and DRESS syndrome are medical emergencies that require immediate treatment. If you experience any symptoms of these allergic reactions, call 911.

8. Difficulty breathing

Gabapentin works by "slowing the brain down." If you take gabapentin with other medications or substances that slow down the brain, dangerous effects can occur. This includes slowed breathing, confusion, and extreme sleepiness. And the risk is higher for people with existing breathing problems.

Medications that affect your brain in this way are best avoided in combination with gabapentin. These are the same medications that are known to increase drowsiness. Additionally, gabapentin and alcohol is another risky combination to avoid.

When taken alone, gabapentin is generally considered safe. But research has found that the combination of gabapentin and opioids can increase the risk of overdose death.

If you're taking gabapentin with any other medications, check with your healthcare team to make sure it's safe. And if you notice excessive sleepiness or trouble waking up after taking gabapentin, let your prescriber know right away.

9. Diarrhea

Gastrointestinal (GI) side effects are possible with gabapentin, though they're not very common. Still, of these GI side effects, diarrhea was most commonly reported in studies.

If you have diarrhea after starting gabapentin, sticking with bland foods might be a good idea as your body adjusts to taking a new medication. The BRAT diet is a tried-and-true fix for helping with diarrhea in the short term. The diet consists of starchy foods like bananas and toast. But you should only continue this diet for as long as it's needed, as following it for too long can lead to constipation. Let your prescriber know about any ongoing bowel changes.

Nausea and vomiting are other GI side effects that can occur with gabapentin. Taking your doses with food might help prevent this.

10. Erectile dysfunction

Erectile dysfunction (trouble getting or keeping an erection) is a possible gabapentin side effect in men. But it's unclear how likely gabapentin is to cause sexual side effects like erectile dysfunction. This is partly because erectile dysfunction can occur for several reasons, including many health conditions and other medications.

Let your prescriber know if you're having erection problems after starting gabapentin. They can help you figure out the cause. They may offer effective medication treatments to help, such as Viagra (sildenafil) or Cialis (tadalafil).

11. Memory problems

Some studies show that gabapentin may have effects on your memory. But we need more research on this topic to be sure. Still, older adults are more at risk of memory issues and medication side effects in general.

A 2022 study looked at 480 adults aged 65 and older who were taking gabapentin. Researchers gave cognitive tests to the participants before starting gabapentin, and one year after starting it. The researchers found that cognitive scores declined after starting gabapentin.

Another study conducted in Taiwan looked at patient records collected over 18 years. Researchers found a link between past gabapentin use and being diagnosed with dementia.

While these studies suggest a connection between gabapentin and memory problems, more research is needed to know for sure. Still, talk to your prescriber about gabapentin's long-term effects on the brain, especially if you're over 65 and take other medications that affect the brain.

12. Withdrawal symptoms

Some medications can cause side effects or health problems if you stop taking them abruptly. This is true for all gabapentin products, which can cause withdrawal symptoms like anxiety, agitation, and nausea or vomiting. More seriously, stopping treatment with gabapentin abruptly can lead to seizures.

If you want to stop taking gabapentin, don't make any changes without talking to your prescriber. If it's appropriate, they can help you come up with a plan to slowly lower your dose.

13. Suicidal thoughts and behavior

Antiseizure medications, including gabapentin, can increase your risk for suicidal thoughts or behavior. This can begin as early as one week after you begin taking gabapentin.

If you're taking gabapentin and you experience any new or worsening depression, or any changes in your behavior, let your prescriber know immediately.

If you or someone you know is having thoughts of suicide, you're not alone, and help is available. Call the National Suicide Prevention Lifeline at 988, or text "HOME" to 741-741 to reach the Crisis Text Line.

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