Gabapentin appears to work by altering electrical activity in the brain and influencing the activity of chemicals called neurotransmitters, which send messages between nerve cells.
Brand names for gabapentin include Horizant, Gralise, and Neurontin. The medication is available in capsule, tablet, or liquid form.
In this article, we describe the uses, dosages, and side effects of gabapentin. We also look into the associated risks and other safety considerations.
Gabapentin can prevent or control seizures.
Gabapentin's primary use is to prevent or control seizures. It works by calming down nerve activity to reduce seizure intensity or occurrence.
Some people take other medications with gabapentin to control epilepsy symptoms.
Gabapentin can also help reduce post-herpetic neuralgia, a burning or stabbing nerve pain that is a common complication of shingles.
Extended-release gabapentin (Horizant) tablets can treat restless legs syndrome (RLS), a condition characterized by uncomfortable sensations in the legs and a strong or irresistible urge to move the lower limbs.
A study from 2016 suggests that gabapentin combined with oxycontin, an opioid painkiller, can control pain and increase the quality of life for people with severe cancer pain. However, doctors do not typically prescribe gabapentin for this purpose.
The right dosage of gabapentin depends on several factors, including:
- the type and brand of gabapentin
- the strength of the product
- the condition
- the person's kidney function
- their weight, age, and general health
The number of daily doses, the hours that should pass between the doses, and the length of time that a person takes gabapentin will vary among individuals.
A person should take some forms of gabapentin with food, but for other forms it is unnecessary.
Anyone prescribed the Horizant brand of gabapentin for RLS should take it only in the evening or at night.
Some brands or dosages require a person to break the tablets in half. Always use the other half with the next dose, or as soon as possible.
Never break or chew extended-release gabapentin tablets — always swallow them whole.
It is vital to take only the recommended dose of gabapentin and not to continue using it for longer than prescribed. If a person misses a dose, they should follow the instructions on labeling or call a pharmacist for advice.
Side effects of gabapentin can include dizziness and feeling sleepy.
Image credit: Rachel Demsick, 2013
The most common side effects, occurring in 10 percent of participants on gabapentin, were:
- water retention (swelling of the arms, hands, legs, and feet)
- problems walking
Serious side effects were not common and were the same in those taking the placebo.
Children and older adults may be most susceptible to adverse reactions to gabapentin. Possible side effects include:
- back or chest pain
- upset stomach
- increased appetite and weight gain
- blurry vision
- changes in mood
- a cough
- a fever
- flu-or cold-like symptoms
- hoarseness and dry mouth
- memory loss
- mouth ulcers
- shortness of breath
- a sore throat and swollen glands
- urinary problems
- uncontrollable eye-rolling
In children, some of the more common adverse reactions are:
- anxiety, depression, or other mood changes
- behavioral problems
- changes in performance at school
- lack of concentration
Individuals taking gabapentin should talk to their doctors about any side effects that occur, especially if they are severe, ongoing, or get worse.
Seek emergency medical treatment if symptoms of a severe or allergic reaction occur. These include:
- breathing difficulties
- extreme dizziness
- severe weakness
- swelling of the face, lips, tongue, or throat
- yellowing of the skin or eyes (jaundice)
People can report adverse drug reactions to the United States Food and Drug Administration (FDA) at 1-800-FDA-1088 or at https://www.fda.gov/safety/medwatch.
Safety and risks
People taking gabapentin should be aware of the following:
Risk of suicidal thoughts or behaviors
Some people experience thoughts of suicide or exhibit suicidal behavior when taking gabapentin or other anticonvulsants.
If a person or their loved one notices changes in mood or behavior, they should contact a doctor immediately.
Interactions with other medications and substances
Gabapentin can interact with other prescription or over-the-counter medications, vitamins, and herbal supplements.
Be sure to give the doctor a full list of current medications and supplements before taking gabapentin.
Results of a 2017 review suggest that the following are the main substances that interact with the drug:
- caffeine, which is present in tea, coffee, and cola
- ethacrynic acid, a diuretic
- losartan, a medication for high blood pressure
- magnesium oxide, a mineral supplement and antacid
- mefloquine, an antimalarial drug
- morphine, an opioid pain medication
- phenytoin, an anti-seizure medication
If gabapentin causes sleepiness, speak to the doctor before taking other medications that can also cause drowsiness, including:
- antianxiety medications
- cold and flu medications
- muscle relaxers
- narcotics (pain medications)
- sleeping pills
Presence of other health conditions
To ensure that gabapentin is safe to take, a person should tell their doctor if they currently have or have ever experienced:
- breathing problems
- depression or other mental health disorders
- dialysis treatment
- drug and alcohol misuse issues
- heart disease
- kidney disease
- liver disease
- seizures (if taking gabapentin for conditions unrelated to seizures)
Risks during pregnancy and when breastfeeding
Pregnant women should only take gabapentin if it is unavoidable.
People who are pregnant, or intend to become pregnant, should tell their doctor before taking gabapentin.
Pregnant women should only take the drug if it is absolutely necessary. However, it is also essential to control seizures while pregnant.
Do not start or stop taking gabapentin for seizure control before talking to the doctor, who will assess the potential risks and benefits.
Gabapentin passes into breast milk, but its effects on babies are unknown. It is best to discuss this issue with a doctor before breastfeeding.
Potential for a drug allergy
Individuals with gabapentin allergies should not take the drug.
Also, the medication may contain other ingredients that can trigger allergy symptoms in some people. Discuss all drug and food allergies with a doctor before taking gabapentin.
Other safety considerations
Because gabapentin can cause drowsiness, anyone taking the drug should exercise caution while driving or using machinery.
Do not take antacids within 2 hours of taking gabapentin, as antacids reduce the body's ability to absorb the drug.
People should also avoid alcohol or limit their intake while on gabapentin because there is a risk of adverse reactions.
Doctors prescribe gabapentin to control seizures, treat RLS, and reduce nerve pain.
Several types of gabapentin are available, and different forms can treat different medical issues.
The right dosage will vary, depending on the condition and other factors. A doctor can best advise about drug interactions and other safety considerations.
Although gabapentin has the potential to cause several adverse reactions, many people experience no serious side effects.