Methocarbamol side effects and drug information

Methocarbamol is a prescription drug in the form of an oral tablet that is available in the market in the form of its brand-name drug called Robaxin. Not to worry, though, since Methocarbamol is also available with its generic substitute, which usually costs less. Also, there are cases that there is no available brand-named version in every dosage strength or even form.

Molar mass 241.241 g/mol
PubChem CID 4107
ChEMBL Id 1201117
ChemSpider ID 3964
CAS ID 532-03-6
Read up


What is Methocarbamol?

This medication also takes the form of an injectable solution; however, this should only be given by health professionals.

Why it’s used

Methocarbamol is mainly used to treat muscle pains and stiffness, and most commonly prescribed with rest and some physical therapy.

How it works

This medicine is included in the class of drugs that are called muscle relaxers or muscle relaxants. The term “class of drugs” is one group of drugs that work in the same if not a similar way, and these drugs are usually used to relieve pain from similar conditions.

It is believed that Methocarbamol reduces the pain your body feels by decreasing the message of the pain of the body and slows down the nervous system. In this way, your muscles are relaxed, and you feel relief.

Side Effects

Common side effects

Just like other medicines, there are side effects that a person experiences when drinking Methocarbamol. One of the most common to be experienced when drinking this medicine as an oral tablet is a drowsiness since you feel your muscles relaxing. There are also other common side effects like headaches, dizziness, lightheadedness, and sedation. 

These side effects are usually mild and will disappear after a few days to a couple of weeks. If, in any case, that the effects do not go away, immediately talk to your physician or pharmacist.

Serious side effects

Depending on the reaction of your body, you may also experience severe side effects. Should this happen, immediately call your doctor.

Make sure to get your emergency numbers ready and be alert if something feels wrong in your body. Some of the severe side effects include allergic reaction with rashes, itching, hives, swelling in your face, your eyes, your throat, and your tongue, difficulty in breathing, and chest tightness. 

You can also experience Angioneurotic edema or the swelling of the lower layer of skin and tissues where there are a significant intracellular protein loss and plasma exudation. The symptoms included in Angioneurotic edema are swollen tissues, pain in the abdomen, and swelling of the voice box. 

For injectable Methocarbamol, the symptoms a patient can feel are the swelling of the veins where the patient was injected, pain on the injected part, skin peeling on the injected part, and redness or swelling on the injected part. 

People with jaundice will also experience yellowing of skin and whiteness of eyes. The medicine might also affect your vision, and you can experience having double vision, blurred vision, and uncontrolled eye movement. You can also experience a pink eye wherein you will have red, watery, and itchy eyes. 

More symptoms of Methocarbamol are slowed heart rate, flushing, low blood pressure, low white blood cell counts, memory loss and sudden confusion, lack of coordination, sleeplessness, seizures, and vertigos.

Dosage and Administration

The dosage information on Methocarbamol tablets will depend on many things that the doctor should consider. All possible dosages and drug forms can affect your body in different ways. To determine your dosage, the things to be considered are your age, your condition, and how severe it is, the other medical conditions that you have that may react to the medicine, and how you respond to the first dosage. 

Some forms of Methocarbamol include the oral tablet of the generic Methocarbamol, which can be 500mg and 750 mg. 

There is also a Methocarbamol available in the branded-named Robaxin, which is another oral table but with the only 500mg of strength, while there is also a Robaxin -750 with 750mg strength. 

There are also differences in dosages per age of a person if you are an adult aged from 18 to 64 years old, the typical starting dose is 6,000 mg per day while your standard maintenance dose ranges from 4,000–4,500 mg per day. There is a possibility that your doctor will set you up in higher dosage in the first two or three days, and then it will be reduced to about 4,000 mg daily. 

For children aged 16 to 17 years old, the typical starting dose is about 6,000 mg per day, while the average maintenance dose is 4,000–4,500 mg per day. Just as with the adult, the treatment will be higher than usual on the first three days, and then it will be decreased to the 4,000 mg daily dosage. For the children aged o to 15, however, it has yet to be confirmed if the methocarbamol is safe and effective to the usage of the children lower than 16 years old. 

The senior citizens or people aged 65 years old and older have a very different level of dosage. The kidneys of the elderly generally do not function as properly as they were young. This may cause the body to be slower in processing drugs, which can result in the medication staying for a more extended period in the body.

This heightens the risk of side effects to a person so that the doctor will start with the lower dosage of the medication, or a different schedule will be used. This is a technique to help maintain the levels of drugs in the body and keep it from building up too much. 

Drug Interaction

Taking in Methocarbamol does not only give you a side effect on your body, but it also interacts with the current medications, vitamins, and substances you are currently taking in. An interaction happens when a substance or drugs change the way the medicine works for you, which makes it very harmful or might even prevent the medication from working.

To avoid interactions, the doctor should know all about your medical history, condition, and other medications. This way, he can manage the side effects and drug interactions for you. Be sure to let your doctor know about all the things mentioned earlier. To also make sure how the drug may interact with other medications and prescription you have, do not hesitate to ask your doctor or pharmacist.

Warnings and Precautions

The doctor must monitor the progress of the patient through regular visits and check-ups. This ensures that the medicine the patient is taking in properly working and unwanted side effects can be prevented and maintained.

It is also very important that you check with your physician before taking  the medicine if you have plans to drink substances that will affect your central nervous systems, like alcohol or other medication. The usage of alcohol and other drugs that may affect the CNS together with risperidone may make the side effects of the medicine worse, like dizziness, poor concentration, drowsiness, unusual dreams, and trouble sleeping. 

Some of the examples of medicines that may affect the CNS are antihistamines also known as medicine for allergies and colds, some sedatives, a tranquilizer or sleep medicine, medication for depression, medication for anxiety, prescription pain medicine also known as narcotics, medicines used for attention deficit and hyperactivity disorder, medication for seizures and barbiturates, muscle relaxants, and anesthetics which includes dental anesthetics.

The medication may be the cause of some people to be dizzy and drowsy. Be sure that you know your body’s reaction to the medicine before you drive, use machines that would need you to be alert or do anything else that could endanger you if you are not alert. 

You also have to make sure that your doctor or dentist that will treat you know that you are using Methocarbamol, because this medicine may affect the results of certain medical examinations. 

Remember never to take medicine unless prescribed by your doctor and that you should not take other medication without discussing it with your doctor first. This should include all medicine, prescribed or not-prescribed, also known as over the counter medicines, herbal, and vitamin supplements. 

Heed the warning that certain substances will adversely affect you when you drink it together. Drinking alcohol will increase the effect of sedation of the medicine. If you are planning to take alcohol while drinking the medication, be sure to talk to your doctor about it so they can advise you.

Also, Methocarbamol can be the cause of your coordination or concentration impairment. You shall never take Methocarbamol if you are operating heavy machinery, or if you are driving a motor vehicle unless you are aware of how medications affect you. 

Overdose and Contraindications

Interactions that increase the risk of side effects

Simultaneously drinking methocarbamol with drugs have contraindications in your body and increases the risk of harmful side effects. These drugs must be discussed with your doctor first to make sure that it is not detrimental and useful for you.

If you are taking anxiety drugs like lorazepam, diazepam, clonazepam, and alprazolam, pain drugs including oxycodone, hydrocodone, tramadol, and morphine, antidepressants, especially amitriptyline, doxepin, and imipramine, and herbal products like kava-kava or valerian root, make sure you talk to your doctor about the side effects of the drugs.