9 Gabapentin Side Effects Worth Knowing About - GoodRx (2024)

Gabapentin is FDA-approved to treat certain types of seizures, as well as nerve pain from shingles (postherpetic neuralgia).

Gabapentin is an immediate-release (IR) medication that’s available under the brand-name Neurontin. Two other formulations of gabapentin are also available: Horizant and Gralise. Both of these extended-release (ER) medications are approved to treat postherpetic neuralgia. And Horizant is approved to treat restless leg syndrome.

Gabapentin is also used off-label to treat conditions such as anxiety and nerve pain from diabetes. It may also help people stop drinking alcohol.

Though gabapentin has many potential uses, it can cause side effects. We’ll cover 9 of the most important gabapentin side effects to know about here.

1. Dizziness

Dizziness is the most common gabapentin side effect. 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 healthcare provider 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 provider know. They may recommend a lower dose of gabapentin or another medication altogether.

2. Tiredness

After dizziness, tiredness is the second most common gabapentin side effect. According to studies, about 20% of people taking gabapentin experience tiredness. 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 — including opioids, benzodiazepines, and alcohol— can worsen these effects.

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

3. Fluid buildup

People taking gabapentin may experience fluid buildup in their legs (peripheral edema). This occurs in about 2% to 8% of people taking gabapentin. It can also be a side effect of Horizant and Gralise.

Peripheral edema from gabapentin may be more likely in older adults. It may also be more likely with higher doses of the medication (greater than 1,800 mg). And it’s most likely to happen within the first month of treatment.

This side effect can be serious for people with heart conditions because it can put excess stress on the heart. It can also be a problem for people with kidney or liver problems.

Although it’s uncommon, edema from gabapentin may lead to weight gain. If you experience edema or weight gain while taking gabapentin, let your healthcare provider know, and do not stop taking the medication until you speak with them.

Your provider will likely 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 the cause of the edema or weight gain, your provider may recommend a lower dose or that you stop taking the medication altogether. If this isn’t possible, they may recommend that you take medication to lower edema, like a diuretic.

4. Eye problems

Gabapentin may cause issues with your eyes. This may include blurred vision, double vision, or rapid eye movements that you can’t control. These issues are less common with Horizant and Gralise than they are with IR gabapentin.

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 healthcare provider if you have any changes in your vision. They may refer you to an eye specialist to determine if gabapentin is the cause.

5. 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 when taking gabapentin. So, if your child is taking gabapentin and you notice any changes in their mood or behavior, speak to their healthcare provider immediately.

6. Severe allergic reactions

A rare but serious side effect of gabapentin is severe allergic reactions. 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 drug reaction with eosinophilia and systemic symptoms (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.

7. Trouble 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 and substances that affect your brain in this way and are best avoided in combination with gabapentin include:

• Opioids, like hydrocodone/acetaminophen

• Benzodiazepines, like alprazolam (Xanax)

• Sleep medications, like zolpidem (Ambien)

• Alcohol

When taken alone, gabapentin is generally considered safe. But the involvement of gabapentin in opioid overdose deaths is on the rise. This means that more and more people who die from opioid overdose are being found to have gabapentin in their system as well.

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

8. 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. 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 healthcare provider. If it’s appropriate, they can help you come up with a plan to slowly lower your dose.

9. Suicidal thoughts and behavior

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 healthcare provider know immediately. And if you or someone you know is having thoughts of suicide, you’re not alone; help is available. Call the National Suicide Prevention Lifeline at 988, or text HOME to 741-741 to reach the Crisis Text Line.