Uniflex combines paracetamol 450 mg with orphenadrine citrate 35 mg. It treats painful muscle spasm — back and neck spasm, and spasm after injury — pairing a painkiller with a muscle relaxant. It causes drowsiness and dry mouth, and is intended for short-term use.
What is Uniflex?
Uniflex, formerly sold as Besenol NC, contains two ingredients:
- Paracetamol 450 mg — a simple painkiller
- Orphenadrine citrate 35 mg — a muscle relaxant
The combination addresses two parts of the same problem. Paracetamol acts centrally to reduce pain perception. Orphenadrine works in the brain and spinal cord to reduce the nerve activity driving muscle spasm — it relaxes the muscle rather than acting on the pain directly.
That pairing makes sense because of how muscle pain actually behaves. When you strain your back, surrounding muscles tighten protectively. That guarding is useful for a day or so and then becomes part of the problem: tight muscle hurts, restricts movement, and slows recovery. A painkiller alone treats the pain while leaving the spasm; a muscle relaxant alone leaves the pain. Together they break the cycle.
Orphenadrine also has antimuscarinic and antihistamine properties, which is where its side effects come from — dry mouth, blurred vision, drowsiness and constipation. The same ingredient at a higher strength is sold alone as Norflex.
What is Uniflex commonly used for?
- Acute painful muscle spasm — lower back spasm, neck spasm, spasm after a strain or injury.
- Muscle spasm with musculoskeletal conditions, where the spasm itself is worsening the pain.
- General pain with a muscular component.
- Tension-related neck and shoulder pain.
The most useful thing to know alongside the medicine is what actually resolves back pain.
Movement is the treatment. Current guidance for ordinary mechanical back pain is to stay as active as the pain allows, returning to normal activity as soon as possible. Prolonged bed rest makes recovery slower, not faster. Uniflex is there to make movement possible — it is not a substitute for it.
Most back pain settles within weeks without imaging or specialist input. Scans are generally unhelpful early on and often show age-related changes unrelated to the pain.
It is for short-term use. If spasm is not settling within a week or two, the answer is usually assessment and physical treatment rather than continuing tablets.
How Uniflex fits into this medicine category
| Group | Examples | What it does |
|---|---|---|
| Painkiller + muscle relaxant | Uniflex, Norflex Co | Treats pain and spasm together |
| Muscle relaxants | Orphenadrine (Norflex), methocarbamol | Reduces the nerve drive causing spasm |
| Simple analgesics | Paracetamol (Donapan, Zypol) | Relieves pain |
| Anti-inflammatories | Ibuprofen, diclofenac | Reduces inflammation and pain |
| Corticosteroids | Prednisone | Suppresses inflammation, as courses |
See the pain, inflammation and musculoskeletal medicines hub.
What to check before using Uniflex
Do not take any other paracetamol product. Each tablet contains 450 mg — close to a full standard dose. Cold and flu remedies, sinus tablets and combination painkillers such as Mybulen or Stilpane commonly contain paracetamol, and adding one is how accidental overdose happens.
Do not drive until you know how it affects you. Drowsiness is common.
Speak to a pharmacist or doctor if:
- You have glaucoma, particularly narrow-angle. Antimuscarinics can raise pressure in the eye.
- You have an enlarged prostate or difficulty passing urine.
- You have myasthenia gravis.
- You have a heart condition, especially a fast or irregular heartbeat.
- You have a bowel obstruction or significant constipation.
- You have liver disease, or drink alcohol heavily — the paracetamol matters here.
- You are pregnant or breastfeeding.
- You are older. Antimuscarinic medicines are associated with confusion and falls in older adults.
- You take other antimuscarinic medicines — some antidepressants, antihistamines, bladder medicines. The effects add up.
- You take other sedating medicines, or drink alcohol.
Follow the pack instructions and note the maximum in 24 hours.
Possible cautions and when to ask a pharmacist or doctor
Expect dry mouth and drowsiness. These are the commonest effects. Blurred vision, constipation and difficulty passing urine also occur.
Paracetamol overdose is a medical emergency with no early warning. Someone who has taken too much may feel entirely well for a day or more while liver damage develops. Go to an emergency department immediately with the packaging, even if they seem fine. Doubling up on paracetamol through another product is the usual route.
Confusion in older adults is a recognised risk with this class. Report new confusion, agitation or unsteadiness in an elderly person — it may be the medicine.
Alcohol adds to the sedation and, separately, to the risk to the liver.
Keep moving. For back pain, gentle activity within the limits of the pain speeds recovery.
Short-term use only. If spasm persists beyond a week or two, seek assessment rather than continuing.
Seek medical attention for eye pain with blurred vision or halos around lights, inability to pass urine, palpitations or an irregular heartbeat, confusion, or a rash with swelling. See a doctor urgently for back pain with numbness in the groin or inner thighs, loss of bladder or bowel control, or leg weakness — those need immediate assessment and are not simple muscle spasm.
Related medicine guides
- Browse Pain, Inflammation & Musculoskeletal Medicines guides
- Read: Prednisone used for
- Read: Donapan used for
Frequently asked questions
What is Uniflex used for? Painful muscle spasm — back and neck spasm, and spasm after injury. It contains paracetamol and the muscle relaxant orphenadrine.
Was it called something else before? Yes, it was previously sold as Besenol NC.
Can I take paracetamol with it? No. Each tablet already contains 450 mg of paracetamol. Check cold and flu remedies too.
Will it make me drowsy? Commonly, yes. Do not drive until you know how it affects you, and avoid alcohol.
How is it different from Norflex? Norflex contains orphenadrine alone at a higher strength. Uniflex pairs a lower amount of orphenadrine with paracetamol.
Should I rest my back? Stay as active as the pain allows. Prolonged bed rest slows recovery — the medicine is there to make movement possible.