10 Gabapentin Side Effects You Should Know About

Gabapentin (Neurontin) is a medication that’s often used to treat nerve pain, seizures, and anxiety or sleep problems. It comes as immediate-release capsules, and it’s also available as extended-release tablets under the brand names Horizant and Gralise.

Though it has many potential uses, gabapentin also has several side effects to be aware of. Some are mild, but others may be more serious or bothersome — especially if you’re first starting the medication or increasing your dosage.

In this article, we’ll walk through the most common side effects of gabapentin, how to manage them, and when to seek medical care. Whether you’ve just started taking gabapentin or are thinking about it, knowing what to expect can help you feel more confident about your treatment plan.

Gabapentin side effects at a glance

Below are lists of gabapentin side effects reported in clinical studies. Keep in mind that these aren’t comprehensive lists. So it’s best to touch base with your healthcare team about any side effects you experience, even if they aren’t listed here.

Common gabapentin side effects include:

• Vertigo (dizziness)

• Drowsiness

• Fatigue

• Edema (fluid buildup)

• Trouble with balance or coordination

• Nausea and vomiting

• Unusual eye movements

• Diarrhea or constipation

• Dry mouth

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Less common gabapentin side effects include:

• Blurry or double vision

• Weight gain

• Flu-like symptoms in kids

• Tremor

• Restlessness

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

Rare but serious gabapentin side effects and risks include:

• Mood or behavior changes (more likely in children)

• Withdrawal symptoms, such as seizures, if stopped abruptly

• Suicidal thoughts or behaviors

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

• Severe allergic reactions, such as angioedema and drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome

Learn more about 10 of these side effects and risks below.

1. Dizziness

Dizziness is the most common side effect of gabapentin. Along with causing dizziness, gabapentin can worsen your coordination. This can increase your risk of falls, which is especially dangerous if you’re an older adult.

If you’re just starting to take gabapentin or your dosage has increased, avoid driving and other activities that require alertness or coordination. Once you see how gabapentin affects you, you and your prescriber can decide if and when it’s safe to resume these activities.

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

2. Tiredness

Taking gabapentin can also make you sleepy. You may also feel weaker or have less energy than usual. As with dizziness, these side effects can affect your ability to perform some activities safely.

Tiredness related to gabapentin may improve over time as your body adjusts to the medication. But to limit this side effect, work with your prescriber to find the lowest gabapentin dosage that’s effective for you. And if your tiredness doesn’t improve or is affecting your daily life, let your healthcare team know.

Taking gabapentin with other medications or substances that cause drowsiness can worsen its effects. It can also raise the risk of dangerously slowed breathing and even overdose in some cases. Examples of medications and substances that can interact with gabapentin in this way include:

• Opioids, such as oxycodone (Roxicodone, OxyContin)

• Benzodiazepines, such as alprazolam (Xanax)

• “Z-drugs,” such as zolpidem (Ambien)

• Certain antidepressants, such as trazodone

• Benadryl (diphenhydramine)

• Muscle relaxers, such as cyclobenzaprine (Amrix)

• Alcohol

It’s best to avoid combining gabapentin with these substances unless your prescriber OKs it.

3. Swollen arms and legs

Gabapentin is a common medication-related cause of peripheral edema. This condition is characterized by excess fluid and swelling in the body, often in the arms and legs. Edema is more likely in older adults. It’s also more likely with higher gabapentin dosages (i.e., greater than 1,800 mg per day). 

Often, edema from gabapentin is mild and doesn’t cause serious issues. But for people living 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.

4. Stomach-related side effects

Gastrointestinal (GI) side effects are possible with gabapentin. These side effects include nausea, diarrhea, and constipation.

If you have diarrhea after starting gabapentin, sticking with bland foods might be a good idea while your body adjusts to the medication. The BRAT diet (bananas, rice, applesauce, toast) is a tried-and-true tool for managing diarrhea in the short term.

If constipation happens, focus on hydration and fiber-rich foods. You can also try an over-the-counter (OTC) stool softener or laxative if needed. But if your constipation persists, be sure to let your prescriber know.

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

5. Blurred vision and other eye problems

Gabapentin may cause eye-related side effects in some cases. These include:

• Nystagmus (rapid, uncontrollable eye movements)

• Blurry vision

• Double vision

Reach out to your prescriber if you notice any changes in your vision. They may refer you to an eye specialist to determine the best approach.

6. Weight gain

Weight gain isn’t a common gabapentin side effect. But edema can sometimes lead to temporary weight gain due to the excess fluid in your body. Eating a balanced diet and avoiding high-sodium foods can help reduce the chance of weight gain from gabapentin.

If you experience weight gain while taking gabapentin, let your prescriber know. But don’t stop taking the medication until you speak with them. If your prescriber determines that gabapentin is the cause, they may recommend a lower gabapentin dosage or a medication to help remove excess fluid, such as a diuretic.

Your prescriber may also 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.

7. Sexual side effects

It isn’t common, but gabapentin can cause sexual side effects in some people. This could be erectile dysfunction, decreased sex drive, or trouble orgasming.

Let your prescriber know if you’re having sexual problems after starting gabapentin. They can help you figure out the cause and possible treatment options.

8. Mood changes

Though these side effects aren’t common, some people have reported new or worsening depression and anxiety while taking gabapentin. The medication may also cause more severe mood changes in children ages 3 to 12, including:

• Mood swings

• Aggressive behavior 

• Trouble concentrating 

• Lowered ability to perform at school

• Restlessness and hyperactivity

Gabapentin can also increase your risk for suicidal thoughts or behavior. This can begin as early as 1 week after you begin taking gabapentin.

If you’re taking gabapentin and you experience any new or worsening mood or behavior changes, let your prescriber know right away.

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.

9. Severe allergic reactions

While rare, gabapentin can cause serious allergic reactions, such as angioedema or anaphylaxis, at any point during treatment.

Angioedema involves swelling that usually occurs in the face, mouth, or throat. Anaphylaxis often shows up as hives and itching all over the body. More serious symptoms include trouble breathing, a fast heartbeat, and confusion.

Gabapentin can also cause another type of allergic reaction called DRESS syndrome. This condition usually starts with a fever, rash, and swelling of the lymph nodes. But it can progress and cause damage to major organs, such as 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.

10. Memory problems

Some studies show that gabapentin may have a negative effect on your memory — especially with long-term use. There may also be a link between gabapentin use and being diagnosed with dementia.

While some studies suggest a connection between gabapentin and memory problems, more research is needed to know for sure. Talk to your prescriber about gabapentin’s long-term effects on the brain before taking it, especially if you’re over age 65.

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Written by:

Stacia Woodcock, PharmD

Stacia Woodcock, PharmD, is a pharmacy editor for GoodRx. She earned her Doctor of Pharmacy degree from the University of Kentucky and is licensed in New York and Massachusetts.

Reviewed by:

Austin Ulrich, PharmD, BCACP

​​Austin Ulrich, PharmD, BCACP, is a board-certified ambulatory care clinical pharmacist. Ulrich’s experience includes direct patient care in hospital and community pharmacies.

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