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Muscle Relaxers Side Effects: Do Muscle Relaxers Cause Constipation?

Last Updated: February 23, 2023

Authored by Olivier George, Ph.D.

Reviewed by Michael Espelin APRN

Muscle relaxers are prescription medicines used to treat pain, spasms, or spasticity. Muscle relaxants are acting in the central nervous system and provide temporary relief to the user. As these medicines may look harmless, it is vital to note that side effects of muscle relaxers are harmful for the user, especially in the long run. Do muscle relaxers cause constipation, lower blood pressure, or make one sleepy? Let’s find out.

Common Side Effects Of Muscle Relaxers

If muscle relaxers pills are taken regularly, the user may experience specific side effects, such as:


Can muscle relaxers cause constipation? Yes, patients who start taking these drugs may observe a change in their bowel movements. This is because muscle relaxers cause constipation.


Do muscle relaxers make one sleepy? Yes, another common side effect of muscle relaxers is dizziness. This drug can make one feel tired and sleepy. This statement is particularly true in the case of potential skeletal muscle relaxers side effects, which directly affect the nervous system. Feeling drowsy may also be a sign of overdose on muscle relaxant medication. If the intake of a large dose took place, it is advised to call 911.

Low Blood Pressure

Dry Mouth

Another common side effect of muscle relaxers pills is dry mouth. After taking these pills, the user may experience a dry or parched sensation in their mouth due to the absence of saliva. This condition is known as xerostomia.

Allergic Reactions

This side effect is common not only for common prescription muscle relaxers but to all medicine in general. It is recommended to discontinue using this drug if an allergic reaction is observed – even if it is mild. Typical allergic reactions include swelling in the throat, itching, and chest tightness.
These are the most common side effects of muscle relaxants that the user is likely to experience in the short-term and are not that dangerous. However, the use of these meds in the long term can cause serious problems for the user.

Muscle Relaxers Side Effects

Long Term Effects of Muscle Relaxers

When the drugs are taken for a long time, they can have more severe adverse effects, including:

Weight Gain

Do muscle relaxers make one gain weight? Although these pills do not directly affect the weight, they do invoke drowsiness and loss of activity. Topped with less physical movement due to injury, this can lead to an increase in body mass – if taken for a long time. Thus, it can be said that muscle relaxers make one gain weight. This is more common in cases of serious injuries, where the person is in a wheelchair or on bed rest. OTC back pain muscle relaxers, especially topical formulations, aren’t known for causing weight gain.

Impaired Thinking And Functioning

One of the most severe risks attached to this drugs is that they can impair the user’s thinking and functioning. As mentioned above, they have a sedative effect. This means that impaired eyesight, thought the process and decision-making ability are side effects that may be experienced in the long term.

Sexual Dysfunction

Do muscle relaxers make you last longer in bed? The answer is no. In fact, certain muscle relaxers, as well as benzodiazepines, can lead to sexual dysfunction. Sedative and muscle-relaxing properties of these pills cause sexual dysfunction by lessening interest, excitement, and sensation, and by interfering with the production of testosterone.

Heart Problems


Perhaps the most dangerous risk associated with the intake of this kind of drugs is an addiction. The sedative effect of these pills causes relaxation and numbness, which is the primary reason why they might be abused. Examples of addictive muscle relaxers include baclofen, carisoprodol, and cyclobenzaprine.
Prolonged use of them can make the user physically dependent on these medicine. People addicted to these pills may need professional treatment of addiction in the form of drug detox and rehabilitation program.

Taking Muscle Relaxers While Pregnant

It is believed that medicines should be avoided during pregnancy and breastfeeding. Most of the doctors discourage any medication in such conditions, and this seems comprehensible to an extent because it is hard to know for sure how a drug might affect the body, or any side effects appeared. Also, a lot of medicines act differently within people.

. pregnant woman holding muscle relaxers

Are Muscle Relaxers Safe During Pregnancy?

Taking muscle relaxers increases the risk of experiencing adverse side effects, and that too is not just limited to the mother; it can affect the baby as well. Despite that the majority of them are listed in C pregnancy category, some of the side effects can be lower milk supply, excessive sleepiness in infants, etc.

Can One Take Muscle Relaxers While Pregnant?

Pregnant women who commonly experience neck or backache, especially in the last stages of their pregnancy, might feel a need to take muscle relaxers, but they must consult their doctor before that. Muscle relaxants don’t show up on urine tests and may seem harmless in most cases, but not to a pregnant woman or her fetus. For example, carisoprodol is not recommended during pregnancy, as it may harm the fetus.

Moreover, the side effects of muscle relaxers while pregnant include blurred vision, constipation, acid reflux, and mental impairment. It is also vital to note that side effects can vary from person to person, and during pregnancy, some of these may be more intense or significant. So, the possibility of these must be assessed before taking any such medication.

Coping With Side Effects Of Muscle Relaxers

A doctor should be the one who decides whether the risk of taking medicine is higher than the risk of adverse effects. Herbal muscle relaxant or exercises can be a safe remedy. For example, the doctor might advise a back massage instead of taking pills.
Female doctor measuring blood pressure after muscle relaxers intake
If it is essential to use medication due to the severity of conditions, there are specific tips that patients can use to minimize the side effects:

  • If muscle relaxers cause constipation, the patient must increase their fiber intake and add more leafy green vegetables into their diet along with increased water intake.
  • If muscle relaxers make one drowsy, the patient should take the medication close to their bedtime or nap time.
  • If muscle relaxers cause weight gain, the patient should make sure to indulge in physical activity to limit its effects. The more the patient remains still, the more weight they are likely to gain. Therefore, some physical activity, like a brisk daily walk, is recommended.
  • If muscle relaxers lower blood pressure, the user can take caffeine in any form for an instant spike in the blood pressure. This also helps with the drowsiness that comes with the intake of these medications, but one should always consult a doctor before.

If a patient feels that they become addicted to muscle relaxers seeking help in a rehabilitation facility is advised.

Page Sources

  1. U.S. National Library of Medicine, DRUG RECORD: MUSCLE RELAXANTS, https://livertox.nih.gov/MuscleRelaxants.htm

Published on: August 14th, 2019

Updated on: February 23rd, 2023

About Author

Olivier George, Ph.D.

Olivier George is a medical writer and head manager of the rehab center in California. He spends a lot of time in collecting and analyzing the traditional approaches for substance abuse treatment and assessing their efficiency.

Medically Reviewed by

Michael Espelin APRN

8 years of nursing experience in wide variety of behavioral and addition settings that include adult inpatient and outpatient mental health services with substance use disorders, and geriatric long-term care and hospice care.  He has a particular interest in psychopharmacology, nutritional psychiatry, and alternative treatment options involving particular vitamins, dietary supplements, and administering auricular acupuncture.

24/7 National Substance Abuse Hotline (800) 913-1755