A muscle relaxant
Orphenadrine
A muscle relaxant used for painful muscle spasm, with antimuscarinic (drying) effects.
What is Orphenadrine?
Orphenadrine is a muscle relaxant used to ease painful muscle spasm and stiffness, and it has also been used for some symptoms of Parkinson's disease. It has antimuscarinic effects, which means it can cause dry mouth, blurred vision and difficulty passing urine. It is dangerous in overdose, so it must be kept safely and never exceeded. Extra care is needed in glaucoma and in men with prostate problems.
Education and reference only. This is a plain-language guide to Orphenadrine — it deliberately contains no doses. Doses depend on the person, the brand and the reason for treatment, and belong with your prescriber. Always check the BNF, the product labelling (SmPC) and follow medical advice.
What it is
Orphenadrine is a muscle relaxant used mainly for painful muscle spasm and stiffness, and historically for some symptoms of Parkinson's disease such as tremor and rigidity. It has antimuscarinic (anticholinergic) properties, which give it both some of its effects and several of its side effects. It is taken by mouth and used under medical guidance.
How it works
Orphenadrine acts on the nervous system, with antimuscarinic activity that blocks some of the nerve signals involved in muscle tone and spasm. This can relax tense, painful muscles and, in Parkinson's disease, help reduce tremor and stiffness. The same antimuscarinic action explains drying side effects such as dry mouth and blurred vision.
Company & origin
Originated / developed by: Generic (long-established).
A muscle relaxant with antimuscarinic effects, used in the UK for muscle spasm and previously in Parkinson's disease.
Practical use
How to take Orphenadrine
General, dose-free guidance — always follow your prescriber's and the leaflet's specific instructions.
- Take it regularly as prescribed and do not exceed the amount advised, as it is dangerous in overdose.
- Keep it stored safely out of the reach of children.
- Expect possible dry mouth, blurred vision or constipation; sips of water and fibre can help, and report difficulty passing urine.
- Do not stop or change it without advice if you have been taking it regularly, and ask before adding other drying or sedating medicines.
- If you miss a dose, take it when you remember unless it is nearly time for the next, then skip the missed one — do not double up.
Weighing it up
Advantages & disadvantages of Orphenadrine
Advantages
- Can ease painful muscle spasm and stiffness.
- May help tremor and rigidity in some people with Parkinson's disease.
- Taken by mouth as a regular tablet or liquid, which is straightforward.
Disadvantages
- Antimuscarinic side effects such as dry mouth, blurred vision and urinary problems are common.
- Dangerous and potentially fatal in overdose, so must be handled carefully.
- Needs caution in glaucoma, prostate enlargement and in older people.
Practical use
Good to know
Because of its antimuscarinic effects, orphenadrine commonly causes a dry mouth, blurred vision, constipation and sometimes difficulty passing urine, so it is used cautiously in people with glaucoma or an enlarged prostate. It can be dangerous in overdose, so it must be stored safely out of reach of children and never taken in larger amounts than prescribed. It may cause drowsiness in some people and restlessness or difficulty sleeping in others, so it is taken as your prescriber advises. Tell your doctor about all your other medicines, as combining several drying medicines can add up.
Who should not take it / use with caution
- People with myasthenia gravis should not take it.
- People with closed-angle glaucoma or significant urinary retention or prostate enlargement should usually avoid it.
- It is generally avoided where there is bowel obstruction or certain stomach problems.
- Older people and those on other antimuscarinic medicines need extra caution because effects add up.
Monitoring
- Review of whether muscle spasm or Parkinson's symptoms are improving.
- Watching for antimuscarinic effects such as urinary retention, constipation or confusion.
- Extra care and review in older people and those on multiple drying medicines.
Side effects
- Dry mouth, blurred vision and constipation are common antimuscarinic effects.
- Difficulty passing urine, dizziness, and either drowsiness or restlessness and poor sleep.
- Less commonly, confusion (especially in older people) or a fast heartbeat — report these.
Key interactions
- Other antimuscarinic medicines add to dry mouth, constipation and urinary problems.
- Sedating medicines and alcohol can increase drowsiness.
- Tell your prescriber about all medicines, as several combinations need care.
Available as: Tablets and an oral liquid.
Answers
Orphenadrine: frequently asked questions
Why does it cause a dry mouth?
Orphenadrine has antimuscarinic effects, which reduce some secretions and commonly cause dry mouth, along with blurred vision and constipation.
Is it dangerous in overdose?
Yes, it can be dangerous and even fatal in overdose, so it must be stored safely and never taken in larger amounts than prescribed.
Can I take it if I have glaucoma or prostate problems?
It needs caution and is often avoided in closed-angle glaucoma and significant prostate enlargement, so tell your prescriber about these.
Will it make me drowsy?
It can cause drowsiness in some people and restlessness or poor sleep in others; take care with driving until you know how it affects you.
What if I am taking other drying medicines?
Combining several antimuscarinic medicines increases side effects like constipation and urinary problems, so check with your prescriber.
The wider class
About Muscle relaxants
Orphenadrine belongs to the muscle relaxants class. For how the class as a whole works, its shared safety principles and monitoring, see the full guide.
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Authoritative sources
- BNF
- NICE CKS
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