Common and Serious Side Effects of Orphenadrine You Should Know About

Muscle spasms are common. They’re usually sudden and last between a few seconds to several minutes. But for some people, they can be very painful and last longer. If you’ve ever experienced severe muscle pain or discomfort, your healthcare provider may have prescribed a muscle relaxant to treat it.

Orphenadrine is one muscle relaxant your healthcare provider may consider. When taken as prescribed, it can help relieve painful muscle-related symptoms. But orphenadrine may not be the safest option for certain people, such as older adults. This is due to its side effects, including drowsiness, dizziness, and confusion. Dry mouth, blurry vision, and constipation are also possible.

If you’re considering orphenadrine for your muscle pain or discomfort, it’s a good idea to understand the potential side effects and risks.

Orphenadrine side effects at a glance

Orphenadrine has anticholinergic effects in the body, meaning that it blocks a chemical called acetylcholine. This action causes many of its side effects. Many of them can be managed at home. While less common, serious orphenadrine side effects usually happen at higher doses. But some can also happen when you take a lower dose.

Common orphenadrine side effects can include:

• Dry mouth

• Drowsiness

• Dizziness

• Constipation

• Trouble urinating

• Nausea

• Vomiting

• Blurred vision

• Headaches

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Less common but potentially serious orphenadrine side effects include:

• Fast or irregular heart rate

• Increased eye pressure

• Worsening myasthenia gravis symptoms

• Confusion

• Hallucinations

• Agitation

• Tremor

• Physical dependence and tolerance

If you’re experiencing side effects from orphenadrine, there are a few things you can do to help manage them. We provide helpful tips for dealing with 10 orphenadrine side effects below.

1. Dry mouth

Dry mouth is usually the first side effect you might notice after starting orphenadrine. If this happens, be sure to drink plenty of fluids to keep hydrated. It’s also a good idea to avoid foods and other substances that can worsen dry mouth. Examples include alcohol, tobacco, and salty, acidic, or dry foods.

There are also some steps you can take to try and promote salivation, such as sucking on ice chips and chewing sugarless gum. Over-the-counter (OTC) saliva substitutes are also available, such as Biotene and BioXtra products.

If these tips aren’t helping, ask your provider or pharmacist for more information on how to manage this side effect.

2. Drowsiness

Orphenadrine can cause drowsiness, especially with higher doses. So it’s a good idea to see how it affects you before driving a car or performing activities that require you to be alert.

Drowsiness from orphenadrine may be worse if you take it with other medications and substances (such as alcohol) that can make you tired. Share your current medication list with your healthcare team to check for potential interactions ahead of time.

If your drowsiness is starting to interfere with your daily activities, contact your healthcare provider. They may try lowering your dose to see if that makes you less drowsy.

3. Dizziness

Orphenadrine can also cause dizziness. If you’re feeling dizzy, sit or lie down until the feeling goes away. Change positions slowly, such as when going from sitting to standing, to avoid falling or passing out. Similar to drowsiness, avoid activities that can be dangerous if you’re dizzy, such as driving a car.

If your dizziness is severe, getting worse, or not going away, let your healthcare provider know. Since dizziness can have several causes, they can help determine the culprit. If it’s from orphenadrine, they may try lowering your dose.

4. Constipation

Constipation is also possible with orphenadrine and can be dose-related. Lifestyle changes, such as drinking more water and eating more fiber-rich foods, such as vegetables, beans, and bran, can help prevent or manage constipation. And if it’s safe for you to exercise, adding more movement to your routine may also help.

If needed, your pharmacist can suggest an OTC laxative to help alleviate constipation. But if lifestyle changes and laxatives aren’t helping, talk to your healthcare provider. Constipation can become serious if left untreated. Similar to other side effects covered above, they may lower your dose to lessen this side effect.

5. Nausea and vomiting

In addition to constipation, orphenadrine can cause other gastrointestinal issues, such as nausea and vomiting. You can take your dose with or without food, but taking it with a small snack or meal may help with nausea.

If you’re still feeling nauseous after taking orphenadrine, it may help to avoid foods that can worsen nausea. Examples include high-fat, fried, and spicy foods. You can also try eating bland, starchy foods for a short period of time. Let your healthcare provider know if these changes aren’t helping, or if your nausea is persistent or getting worse.

6. Headache

Some people experience headaches while taking orphenadrine. If occasional headaches are starting to interfere with your daily routine, an OTC pain reliever, such as acetaminophen (Tylenol), may help. Your healthcare team can recommend one that’s safe for you to take. Let them know if your headaches are persistent or getting worse.

Keep in mind that headaches can have many causes, including other medications and health conditions. Your healthcare provider can help you figure out if your headaches are from orphenadrine or something else. If needed, they may try lowering your dose.

7. Urination problems

Orphenadrine can cause urination problems, such as difficulty peeing. This is why you shouldn’t take orphenadrine if you have benign prostatic hyperplasia (BPH), since it may worsen your symptoms. Make sure your healthcare team has your full medical history before starting orphenadrine.

Let your healthcare provider know if you notice changes in how often or how much you’re peeing. If these problems are left untreated, they can lead to more serious issues, such as a urinary tract infection or kidney damage.

8. Fast or irregular heartbeat

Orphenadrine can cause fast or irregular heartbeats, especially if you take more than the recommended amount. However, there have been reports of serious heart rhythm issues with lower doses, too. 

Because of this risk, orphenadrine should be used with caution in people with a history of heart problems or an irregular heartbeat, such as atrial fibrillation. Make sure your healthcare team is aware of any current or prior heart problems before starting orphenadrine.

Contact your healthcare provider right away if you notice a faster or irregular heartbeat while taking orphenadrine. If you also have chest pain or any symptoms that feel severe or life-threatening, call 911 or have someone take you to the nearest ER.

9. Mental status changes

While uncommon, mental status changes, such as confusion, agitation, and hallucinations, are possible with orphenadrine. This may be more likely to happen in older adults, which is one of the reasons orphenadrine isn’t recommended for this age group.

Mental status changes can have many potential causes, so you should contact your healthcare provider right away if they develop. If they’re from orphenadrine, they may lower your dose or switch you to a different medication.

10. Aplastic anemia

Another rare but serious side effect that has been reported with orphenadrine is a blood condition called aplastic anemia. This is where your body isn’t making enough new blood cells, such as red and white blood cells and platelets (cells that help your blood clot). However, it’s not clear if orphenadrine was the cause.

Symptoms of this blood condition include fatigue, an infection that lasts a long time, and easy bruising or bleeding. Let your healthcare provider know right away if these develop. If left untreated, aplastic anemia can lead to serious heart problems, including heart failure.

When should you contact your healthcare provider about orphenadrine side effects?

Contact your healthcare provider if you have any questions or concerns about orphenadrine side effects. Your pharmacist can also be a helpful resource to answer your questions.

Many orphenadrine side effects are more common with higher doses. If any become bothersome or interfere with your daily activities, your provider may try lowering your dose. They can also give you additional tips for how you can manage side effects at home.

While less common, orphenadrine can also cause more serious side effects. Examples include fast or irregular heartbeats and mental status changes, such as confusion. Contact your healthcare provider right away if these develop. Get emergency medical care if any side effects feel severe or life-threatening.

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Written by:

Alyssa Billingsley, PharmD

Alyssa Billingsley, PharmD, is the director of pharmacy content for GoodRx. She has over a decade of experience as a pharmacist and has worked in clinical, academic, and administrative roles.

Reviewed 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.

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