Taking two muscle relaxers at the same time is generally not recommended. Muscle relaxers, also known as skeletal muscle relaxants, work by depressing the central nervous system to provide temporary relief from muscle spasms, pain, and discomfort. When taken correctly and under medical supervision, they are usually safe and effective. However, taking more than the recommended dosage can lead to dangerous side effects and potentially life-threatening complications.
How do muscle relaxers work?
Muscle relaxers work by binding to receptors in the brain and spinal cord. This helps calm abnormal nerve transmissions that cause excessive muscle contractions and spasms. Different muscle relaxers have slightly different mechanisms of action:
- Cyclobenzaprine (Flexeril) – Acts primarily on the central nervous system, not directly on muscle tissue.
- Orphenadrine (Norflex) – Blocks activity of neurotransmitters like norepinephrine.
- Metaxalone (Skelaxin) – Depresses central nervous system activity.
- Methocarbamol (Robaxin) – Inhibits spinal reflexes by affecting interneurons.
- Carisoprodol (Soma) – Blocks pain sensations transmitted from sore muscles to the brain.
- Tizanidine (Zanaflex) – Mimics action of neurotransmitter gamma-aminobutyric acid (GABA).
- Baclofen – Mimics GABA to reduce spasticity.
- Diazepam (Valium) – Enhances activity of GABA to produce sedation.
Even though their mechanisms differ slightly, all muscle relaxers work by suppressing the central nervous system in some way. This reduces the excitability of muscle spindles and interneurons, leading to overall muscle relaxation.
What are the risks of taking two muscle relaxers together?
Taking two different muscle relaxers together, or doubling up on the same one, increases the risks of side effects. Combining medications that have additive effects can cause muscle relaxers to build up to toxic levels in the body. Potential dangers include:
- Excessive sedation – Feeling extremely sleepy, sluggish or drowsy.
- Impaired coordination – Loss of balance, unsteady gait, slurred speech.
- Slowed breathing – Potentially life-threatening respiratory depression.
- Coma – Complete unresponsiveness, inability to be awakened.
- Seizures – Abnormal electrical activity in the brain.
- Heart problems – Slowed heart rate, low blood pressure, cardiac arrest.
Overdosing on muscle relaxers essentially poisons the central nervous system. It disrupts normal neurological function, including the signals needed for breathing and consciousness. Taking too many muscle relaxers can lead to respiratory failure, coma and even death in severe cases.
Which combinations are particularly dangerous?
Certain combinations of muscle relaxers are considered especially high-risk:
- Carisoprodol and meprobamate – Carisoprodol gets converted to meprobamate in the body, leading to toxic buildup if both are taken.
- Cyclobenzaprine and amitriptyline – Similar chemical structures increase likelihood of additive side effects.
- Metaxalone and tizanidine – Both are metabolized by the liver, so can accumulate to toxic levels.
- Chlorzoxazone and metaxalone – May have additive sedative properties.
- Carisoprodol and benzodiazepines – Benzos like Valium also depress the CNS and interact dangerously.
- Any muscle relaxer with opioids or alcohol – All three classes depress breathing and consciousness.
As a general rule, combining any two central nervous system depressants is considered risky. This includes mixing muscle relaxers with anxiety medications, sleep aids, antipsychotics, antidepressants and opioids like morphine. The more substances that depress neural function, the greater the risk of severe sedation, respiratory depression and death.
What about taking the same muscle relaxer twice?
Doubling up on the same muscle relaxer carries similar risks as combining two different ones. Taking twice the recommended dose greatly raises the blood concentration of the medication. Side effects become much more likely. For example:
- Flexeril (cyclobenzaprine) – Recommended max dose is 30mg/day. Taking 60mg may cause extreme drowsiness and confusion.
- Skelaxin (metaxalone) – Normal dose is 800mg, 3 times daily. 1600mg may dangerously depress breathing.
- Soma (carisoprodol) – Should not exceed 1500mg/day. 3000mg can lead to sedation and impaired motor control.
- Valium (diazepam) – Maximum is 40mg/day. 80mg significantly increases risks of overdose.
In some cases, taking twice the recommended amount can be fatal. Always follow dosage guidelines and do not double up on muscle relaxers or mix them without medical approval.
What are the approved uses for muscle relaxers?
Muscle relaxers are FDA-approved for certain medical uses only. Doctors may legally prescribe them for:
- Treating muscle spasms and pain from strains, sprains or muscle injuries
- Managing spasticity in conditions like multiple sclerosis or cerebral palsy
- Relieving discomfort from fibromyalgia, piriformis syndrome or other musculoskeletal disorders
For short-term relief of acute muscle spasms, the usual dosage is one dose every 6-8 hours as needed, up to 3 doses per day. For longer lasting chronic muscle conditions, relaxers may be prescribed on a regular schedule each day.
Muscle relaxers should only be used under medical supervision. It is never safe to increase dosage or frequency, combine multiple relaxers, or take them for reasons other than prescribed.
What conditions should avoid muscle relaxers?
Muscle relaxers should be used with caution or avoided entirely in people with certain medical conditions. Relaxers may be contraindicated or unsafe for:
- History of substance abuse or addiction
- Respiratory problems like COPD or sleep apnea
- Kidney or liver disease
- Myasthenia gravis
- Pregnancy and breastfeeding
- Elderly patients
- Patients taking MAO inhibitors
Doctors also use care when prescribing muscle relaxers for patients taking medications that interact with the central nervous system. This includes antihistamines, opioids, anticoagulants, antidepressants and antibiotics.
What are the side effects of muscle relaxers?
Muscle relaxers may cause a variety of side effects, even when taken as prescribed. Common adverse effects include:
- Drowsiness, dizziness, sedation
- Fatigue, weakness, lethargy
- Blurry vision, double vision, involuntary eye movements
- Dry mouth, nausea, vomiting, constipation
- Headache, confusion, disorientation
- Trouble concentrating, memory impairment
- Anxiety, irritability, mood changes
- Rash, itching, swelling, hives
- Tremors, loss of coordination, unsteady movements
Side effects like dizziness and sedation are more likely at higher doses. But even when taken as directed, muscle relaxers can impair mental sharpness, reaction times and physical abilities.
Can muscle relaxers be addictive?
Some types of muscle relaxers do carry a risk of dependence and abuse. The most potentially addictive options include:
- Carisoprodol (Soma) – Modified form interacts with GABA receptors like a benzodiazepine.
- Chlorzoxazone – Related to benzodiazepines chemically.
- Metaxalone (Skelaxin) – May rarely cause psychological dependence.
- Tizanidine (Zanaflex) – Has similar activity to clonidine and other addictive blood pressure medications.
- Methocarbamol (Robaxin) – Withdrawal may occur after long-term use.
For these reasons, doctors avoid prescribing Soma and other potentially addictive muscle relaxers for long periods. People with a history of substance abuse are at higher risk for developing dependence.
Conclusion
Taking two muscle relaxers together is generally not recommended unless specifically directed by a physician. Muscle relaxers depress the central nervous system, so combining medications can excessively enhance their effects. This may result in dangerous sedation, slowed breathing, loss of consciousness and other adverse effects. Only take muscle relaxers according to medical instructions and never mix, double up or increase dosage unless approved by a doctor.
Certain muscle relaxers should be avoided in people with substance abuse disorders, respiratory disease, impaired kidney or liver function, myasthenia gravis and other medical conditions. Pregnant women, elderly patients and those taking interacting medications should also use caution with muscle relaxers due to increased risks. Even when taken as directed, muscle relaxers can cause side effects like sedation, dizziness, nausea and headache.
Muscle relaxers can provide short-term relief from acute muscle spasms and pain related to strains, sprains or musculoskeletal injuries. They may also be used under medical supervision to manage chronic muscle spasticity in conditions like cerebral palsy. However, muscle relaxers are only safe when used exactly as prescribed. Combining or doubling up on dosages substantially increases the health risks.
