Understanding Drug Interactions: What Not to Take with Anarex?

October 9, 2025 •

4 min read

Each year, preventable adverse drug events lead to significant health crises. Anarex, a combination of Orphenadrine Citrate and Paracetamol, requires careful management [1.6.2]. Understanding what not to take with Anarex is vital for your safety.

Quick Summary

Anarex contains Orphenadrine and Paracetamol, posing risks when mixed with CNS depressants, alcohol, and other anticholinergics. Awareness of these interactions is key to preventing serious side effects.

Key Points

Avoid CNS Depressants: Do not take Anarex with alcohol, opioids, or benzodiazepines to prevent severe drowsiness and respiratory depression [1.3.2, 1.3.5].
Prevent Paracetamol Overdose: Never combine Anarex with other medications containing paracetamol (acetaminophen) to avoid the risk of acute liver damage [1.5.8].
Watch for Anticholinergic Effects: Use caution with drugs like certain antidepressants and antihistamines, as they can amplify side effects like dry mouth, confusion, and urinary retention [1.4.7, 1.6.7].
Inform Your Healthcare Provider: Always disclose your full medication history to your doctor or pharmacist before starting Anarex to ensure safety [1.6.2].
Check All Medication Labels: Carefully read the labels of all over-the-counter products for cold, flu, or pain to check for hidden paracetamol [1.5.8].
Warfarin Interaction: If you take the blood thinner warfarin, regular use of Anarex can increase your bleeding risk and requires monitoring [1.5.7].

Understanding Anarex: What It Is and How It Works

Anarex is a compound medication used to relieve pain and discomfort associated with musculoskeletal conditions like muscle spasms, sprains, and tension headaches [1.3.3, 1.6.2]. It contains two primary active ingredients that work in tandem: Orphenadrine Citrate and Paracetamol (also known as acetaminophen) [1.6.2].

Orphenadrine Citrate (35mg): This is a skeletal muscle relaxant that works centrally, meaning it acts on the central nervous system (CNS) rather than directly on the muscles [1.2.1]. It has anticholinergic properties, which means it blocks the neurotransmitter acetylcholine. This action helps to reduce involuntary muscle spasms and associated pain [1.6.7]. It also possesses weak antihistaminic and local anesthetic effects [1.6.7].
Paracetamol (450mg): This is one of the most common analgesics (pain relievers) and antipyretics (fever reducers) in the world [1.5.3, 1.6.2]. It works by inhibiting prostaglandin synthesis in the brain, which are chemicals involved in signaling pain and elevating body temperature [1.3.3].

The combination of a muscle relaxant and an analgesic makes Anarex effective at breaking the pain-spasm-pain cycle, where pain causes muscles to spasm, and the spasm causes more pain [1.3.3].

Why Understanding Interactions is Critical

Because Anarex contains two different active substances, the potential for drug interactions is multiplied. An interaction can increase the risk of severe side effects, reduce the effectiveness of the medications, or lead to dangerous toxicity [1.3.9]. The sedative effects of orphenadrine and the potential for liver damage from paracetamol are two primary areas of concern [1.4.5, 1.5.3]. Therefore, it's essential for patients and caregivers to be fully aware of what substances and medications to avoid.

The Definitive List: What Not to Take with Anarex

To ensure safety, you must avoid several classes of drugs and substances while taking Anarex. The primary risks involve additive CNS depression, increased anticholinergic effects, and liver toxicity.

1. Central Nervous System (CNS) Depressants

This is the most critical category of interactions. Orphenadrine itself is a CNS depressant, causing drowsiness and impairing coordination [1.4.5]. Combining it with other CNS depressants can lead to profound sedation, dizziness, confusion, respiratory depression, coma, and even death [1.3.2, 1.3.5].

Avoid combining Anarex with:

Alcohol: Alcohol significantly potentiates the sedative effects of orphenadrine [1.3.2]. Chronic alcohol use also increases the risk of severe liver damage when combined with paracetamol [1.5.9].
Opioids: This includes prescription pain medicines like codeine, hydrocodone (found in Norco), and fentanyl, as well as opioids for cough [1.4.1, 1.3.5]. The combination can cause extreme sedation and respiratory depression [1.3.5].
Benzodiazepines: These are medications for anxiety or sleep, such as diazepam (Valium), alprazolam (Xanax), and lorazepam (Ativan) [1.2.2].
Barbiturates and other Sedatives/Hypnotics: Medications used for seizures or sleep, like phenobarbital, can cause additive depressant effects [1.4.1].

2. Other Paracetamol-Containing Products

Taking more than one product containing paracetamol can easily lead to an overdose. The maximum recommended adult dose of paracetamol is 4,000 milligrams (4 grams) per day [1.5.8]. Anarex already contains 450mg per tablet [1.6.2]. Exceeding the daily limit can cause severe, and potentially fatal, liver damage [1.3.9, 1.5.3]. Always read the labels of over-the-counter cold, flu, and pain medications to ensure they do not also contain paracetamol or acetaminophen [1.5.8].

3. Anticholinergic Drugs

Orphenadrine has anticholinergic properties. Taking it with other drugs that have similar effects can lead to an accumulation of side effects [1.6.7].

Symptoms of additive anticholinergic effects include:

Severe dry mouth [1.6.5]
Blurred vision and eye pain (especially in those with glaucoma) [1.6.4]
Urinary retention (difficulty urinating) [1.6.2]
Constipation [1.6.5]
Confusion and hallucinations, particularly in the elderly [1.4.7]
Fast or irregular heartbeat [1.6.5]

Be cautious with:

Tricyclic Antidepressants: Such as amitriptyline [1.4.7].
Some Antihistamines: Especially older ones like diphenhydramine (Benadryl) [1.4.2].
Phenothiazines: Used as antipsychotics or anti-emetics (e.g., prochlorperazine) [1.2.2].
Antispasmodics: Used for stomach cramps or bladder issues [1.6.7].

4. Other Notable Interactions

Warfarin: Regular use of paracetamol can increase the effect of the blood thinner warfarin, raising the risk of bleeding. Your INR (a measure of blood clotting) may need more frequent monitoring [1.5.7].
Certain Seizure Medications: Drugs like carbamazepine, phenytoin, and phenobarbital can increase the risk of liver damage from paracetamol [1.5.1, 1.5.3].
Medications for Tuberculosis (TB): Isoniazid and rifampin can make liver damage from acetaminophen more likely [1.5.3].

Comparison Table: Key Anarex Interactions


Interacting Drug/Substance	Potential Effect	Severity	Action Required
Alcohol	Extreme drowsiness, respiratory depression, increased risk of liver damage [1.3.2, 1.5.9].	High	Strictly avoid.
Opioids (Codeine, Hydrocodone)	Profound sedation, respiratory depression, coma [1.3.5].	High	Avoid combination; use alternative if possible.
Benzodiazepines (Diazepam, Alprazolam)	Increased sedation and impairment of judgment and motor skills [1.2.2, 1.3.2].	High	Avoid combination.
Other Paracetamol Products	Risk of overdose and severe liver damage [1.5.8].	High	Avoid. Always check labels.
Tricyclic Antidepressants (Amitriptyline)	Increased anticholinergic effects (dry mouth, confusion, blurred vision) [1.4.7].	Moderate	Use with caution and monitor for side effects.
Warfarin	Increased risk of bleeding with regular Anarex use [1.5.7].	Moderate	Monitor INR closely with healthcare provider.

Conclusion: Prioritize Safety Through Communication

The dual-action nature of Anarex makes it an effective medication for certain types of pain, but it also elevates the importance of vigilance regarding drug interactions. The most severe risks stem from combining it with CNS depressants like alcohol and opioids, and from accidental overdose by taking other paracetamol-containing products. Always provide your doctor and pharmacist with a complete list of all medications you are taking, including prescription, over-the-counter, and herbal supplements [1.6.2]. This open communication is your best defense against a potentially dangerous drug interaction.

For more authoritative information on medication safety, consider visiting the FDA's resources on drug interactions.

Frequently Asked Questions

Anarex contains two active ingredients: Orphenadrine Citrate, a muscle relaxant, and Paracetamol (acetaminophen), a pain reliever and fever reducer [1.6.2].

No, you should avoid drinking alcohol while taking Anarex. Alcohol can significantly increase the drowsiness and dizziness caused by orphenadrine and also raises the risk of liver damage from paracetamol [1.3.2, 1.5.9].

You must be very careful. Many over-the-counter cold and flu remedies contain paracetamol. Taking them with Anarex can lead to a paracetamol overdose and serious liver damage. Always check the ingredients list [1.5.8].

Taking Anarex (orphenadrine/paracetamol) with ibuprofen is generally considered safe as they work differently, but it's best to consult a healthcare provider first. However, do not take Anarex with other painkillers that contain paracetamol [1.5.7, 1.6.8].

It depends on the type of antidepressant. Combining Anarex with tricyclic antidepressants like amitriptyline can increase side effects such as confusion and dry mouth [1.4.7]. You should discuss all medications with your doctor before combining them.

Signs of a serious interaction include extreme drowsiness, confusion, hallucinations, difficulty breathing, fainting, a very fast or irregular heartbeat, or difficulty urinating. Seek emergency medical help if these occur [1.6.4, 1.6.5].

The orphenadrine in Anarex has anticholinergic effects, which can increase the pressure inside the eye. This is dangerous for individuals with glaucoma [1.6.2].