The imprint R180 is used on a white-to-off-white, oval tizanidine hydrochloride 4 mg tablet. The tablet is about 11 mm long and has a four-part score on the back. Tizanidine is a prescription muscle relaxant used to treat spasticity in adults. Ask a pharmacist to confirm any loose pill before use.
R180 can cause drowsiness, dizziness, weakness, and low blood pressure. Serious interactions can occur with ciprofloxacin, fluvoxamine, alcohol, opioids, sedatives, and some blood pressure medicines. The sections below explain how to identify the pill, how tizanidine is taken, and when to get medical help.
Emergency: Call 911 if someone who may have taken R180 has collapsed, had a seizure, is struggling to breathe, or cannot be awakened. In the United States, call Poison Control at 1-800-222-1222 for any suspected overdose or accidental ingestion. Call even when no symptoms are present. Do not make the person vomit unless a medical professional tells you to do so.
What is the R180 pill?
R180 is a 4 mg tizanidine hydrochloride tablet. It is white to off-white and oval, with “R180” on one side and a four-way score on the other. It is available by prescription.
| Identification detail | R180 tablet |
|---|---|
| Imprint | R180 |
| Active drug | Tizanidine hydrochloride |
| Strength | 4 mg of tizanidine |
| Color | White to off-white |
| Shape | Oval, flat, with beveled edges |
| Size | About 11 mm |
| Reverse side | Four-way score |
| Drug class | Skeletal muscle relaxant |
| Availability | Prescription only |
| DEA schedule | None |
The tablet may come in bottles with different pharmacy or repackager names. Check the imprint and physical details instead of relying on the bottle company alone.
The inactive ingredients include anhydrous lactose, microcrystalline cellulose, colloidal silicon dioxide, and stearic acid. Ask the dispensing pharmacist to check the exact product if you have an allergy or need to avoid a certain ingredient.
Can appearance confirm what a loose pill contains?
A visual match cannot prove the contents of a loose tablet. Damaged, altered, or counterfeit pills may copy the color and imprint of a prescription drug. Keep the pill separate and ask a pharmacist to inspect it. Do not taste it or take it to test its effect.
R179 and R180: what is the difference?
R179 and R180 are both white, oval tizanidine tablets. Their strengths, sizes, and score lines differ.
| Detail | R179 | R180 |
|---|---|---|
| Tizanidine strength | 2 mg | 4 mg |
| Approximate size | 8 mm | 11 mm |
| Score | Divides the surface into 2 sections | Divides the surface into 4 sections |
Read the full imprint before taking either tablet. A one-character difference can identify a different strength or drug.
What should you do if you find an R180 pill?
Keep the tablet away from children, pets, food, and other medicines. Then:
- Check whether it came from a labeled prescription bottle.
- Compare both sides, the color, shape, and size with the original prescription bottle or a trusted pill identifier.
- Ask a pharmacist to confirm the tablet before anyone takes it.
- Call Poison Control at 1-800-222-1222 if someone may have swallowed it by mistake.
Do not give the pill to another person. Tizanidine doses are chosen for each patient, and its interactions can cause a dangerous drop in blood pressure or heavy sedation.
What is tizanidine used for?
Tizanidine treats spasticity in adults. Spasticity causes ongoing muscle tightness, stiffness, or spasms because nerve signals that control muscle tone are disrupted. It can occur with conditions such as multiple sclerosis or a spinal cord injury. An occasional nighttime leg cramp can have different causes and may require different care.
The FDA-approved indication is adult spasticity. A clinician may prescribe tizanidine for another reason after reviewing the patient’s symptoms and medical history. Take it only for the condition listed on your prescription.
Another prescription muscle relaxant, cyclobenzaprine 10 mg, is used for short-term muscle spasms linked to sudden musculoskeletal conditions. Its dose, treatment length, and interaction warnings differ from tizanidine.
How does tizanidine work?
Tizanidine is a central alpha-2 adrenergic receptor agonist. It lowers certain nerve signals in the brain and spinal cord that keep muscles tight. This can reduce muscle tone and spasms for a short period.
R180 dosage and how to take it
One R180 tablet contains 4 mg of tizanidine. Your prescription label sets the dose and timing. A 4 mg tablet strength does not mean every patient should start with 4 mg or take a full tablet.
General adult dosing information includes:
- Recommended starting dose: 2 mg every 6 to 8 hours as needed
- Maximum frequency: 3 doses in 24 hours
- Dose increases: 2 mg to 4 mg per dose every 1 to 4 days, based on response and side effects
- Maximum total dose: 36 mg in 24 hours
These numbers explain the approved dosing range. Follow the directions from your prescriber and pharmacist. Do not raise the dose because one dose seems weak, and do not take an extra dose to replace a missed one.
Can you split an R180 pill?
R180 has a four-way score. Split it only when your prescriber or pharmacist has told you how much to take and has confirmed that your dispensed tablet can be divided. Use a pill splitter on a clean, dry surface. Uneven or crumbling pieces should be checked with a pharmacist.
Should R180 be taken with food?
Tizanidine tablets may be taken with or without food. Choose one method and use it consistently because food changes how much tizanidine reaches the blood. A change in food timing can change the drug’s effect or side effects.
Tablets and capsules can produce different blood levels when taken with food. Use the same form and take it the same way with respect to food each time. Ask your prescriber before switching forms.
What should you do after a missed dose?
If you take tizanidine on a regular schedule, take the missed dose when you remember. Skip it when the next dose is close. Never take 2 doses together to make up for the missed dose. Follow any different instructions printed on your prescription label.
Can you stop taking tizanidine suddenly?
Sudden withdrawal can cause high blood pressure, a fast heartbeat, tighter muscles, tremor, or anxiety. The risk is higher after large doses, long-term treatment, or use with opioids. A prescriber may reduce the daily dose over time. Do not create your own taper or stop long-term treatment without medical advice.
How long does R180 take to work?
Tizanidine is short acting. Under fasting conditions, tablets reached their highest blood level in about 1 hour in a drug study. In a separate clinical study using single 8 mg and 16 mg doses, the largest reduction in muscle tone occurred 1 to 2 hours after treatment. The effect differed among patients and depended on the dose.
The drug’s half-life is about 2.5 hours in healthy adults. Age, liver function, kidney function, food, and interacting medicines can change how long it stays in the body. Do not repeat a dose early because relief has worn off.
Common R180 pill side effects
The most common tizanidine side effects are dry mouth, drowsiness, weakness or tiredness, and dizziness. In multiple-dose clinical trials, the following rates were reported:
| Side effect | Patients taking tizanidine |
|---|---|
| Dry mouth | 49% |
| Drowsiness | 48% |
| Weakness, fatigue, or tiredness | 41% |
| Dizziness | 16% |
In these studies, the median daily dose during steady treatment was 20 mg to 28 mg. These percentages do not predict what will happen after one 4 mg R180 tablet.
Tizanidine can make walking or standing less steady. Rise slowly from a bed or chair. Avoid driving, operating machinery, or doing risky work until you know how the medicine affects you.
Serious side effects that need medical care
Contact a medical professional promptly for symptoms such as:
- Fainting, severe dizziness, or a very slow heartbeat
- Hallucinations, confusion, or unusual behavior
- Yellow skin or eyes, dark urine, pain in the upper-right part of the abdomen, severe tiredness, or loss of appetite
- New vision changes
Call 911 for trouble breathing, swelling of the face, tongue, or throat, or if the person cannot be awakened. These symptoms may point to a severe allergic reaction, extreme sedation, or overdose.
R180 drug and alcohol interactions
Tell your prescriber and pharmacist about every prescription medicine, over-the-counter drug, vitamin, and supplement you use. The interaction groups below need special attention.
Ciprofloxacin and fluvoxamine
Tizanidine must not be taken with ciprofloxacin or fluvoxamine. These medicines can raise tizanidine levels and cause severe low blood pressure, marked drowsiness, and poor coordination.
If either drug appears on your medicine list, contact your prescriber or pharmacist for instructions before your next tizanidine dose.
Alcohol, opioids, and sedatives
Alcohol can raise tizanidine levels and increase drowsiness. Opioids, benzodiazepines, sleeping medicines, tricyclic antidepressants, and other sedating drugs can cause greater sedation when combined with tizanidine. The combination may also cause poor coordination or low blood pressure.
Avoid alcohol while taking R180. Ask a clinician before combining tizanidine with any drug that causes sleepiness.
Blood pressure medicines
Tizanidine can lower blood pressure. Blood pressure medicines can add to this effect and may cause dizziness or fainting. Other alpha-2 agonists can have the same problem. Your clinician may need to review the dose and monitor your blood pressure.
Other medicines that can raise tizanidine levels
Several moderate or weak CYP1A2 inhibitors should be avoided when possible. Examples include zileuton, amiodarone, mexiletine, propafenone, verapamil, cimetidine, famotidine, acyclovir, ticlopidine, and oral contraceptives. A clinician may change the treatment plan or watch for low blood pressure, a slow heartbeat, and excess drowsiness.
Who needs extra caution with tizanidine?
Tell your prescriber before taking R180 if any of these points apply:
- Liver disease: Tizanidine is processed in the liver and can cause liver injury. Liver enzyme tests are recommended before treatment and about 1 month after the highest dose is reached.
- Kidney disease: People with a creatinine clearance below 25 mL/min, a measure of kidney function, clear tizanidine more slowly and may need smaller individual doses.
- Age 65 or older: Older adults may clear the drug more slowly, especially when kidney function is reduced.
- Pregnancy: Human data are too limited to define the risk. Animal studies found developmental harm. Discuss the expected benefit and possible risk with your clinician.
- Breastfeeding: Human milk data are unavailable. A clinician should consider the parent’s need for treatment and possible effects on the baby.
- Under age 18: Safety and effectiveness in children have not been established.
Is the R180 pill a narcotic or controlled substance?
| Question | Answer |
|---|---|
| Is R180 an opioid or narcotic? | No. It contains the muscle relaxant tizanidine. |
| Is tizanidine a controlled substance? | No. It has no DEA schedule. |
| Is a prescription required? | Yes. |
| Can physical dependence occur? | Yes, especially with high doses or long-term use. |
Physical dependence means the body has adjusted to the medicine. It can occur even when a person takes tizanidine as prescribed. It is one reason a prescriber may lower the dose slowly.
R180 overdose symptoms and response
A tizanidine overdose can affect alertness, heart function, blood pressure, and breathing. Reported symptoms include:
- Extreme sleepiness or weakness
- Confusion or loss of consciousness
- Slow heartbeat
- Low blood pressure, dizziness, or fainting
- Slow or shallow breathing
- Coma
Call Poison Control at 1-800-222-1222 in the United States after a suspected overdose or accidental ingestion. Call 911 if the person has collapsed, had a seizure, has trouble breathing, or cannot be awakened. Bring the prescription bottle or provide the imprint, strength, estimated amount, and time taken.
How to store and dispose of R180
Store tizanidine at 77°F (25°C). Short temperature changes from 59°F to 86°F (15°C to 30°C) are permitted. Keep it in its original, tightly closed container away from excess heat, moisture, children, and pets.
Use a medicine take-back program for unneeded tablets. A pharmacist can give local disposal instructions. Do not share the medication or leave loose tablets in household trash where someone could reach them.
Frequently asked questions
What is a white oval pill with R180 on it?
The R180 imprint identifies tizanidine hydrochloride 4 mg when the tablet is white to off-white, oval, about 11 mm long, and has a four-way score on the reverse.
Is R180 Xanax?
R180 identifies tizanidine 4 mg. Xanax contains alprazolam and uses different approved imprints.
Is R180 the same as Zanaflex?
R180 contains tizanidine, the generic drug in Zanaflex. Follow your prescription and ask your prescriber before switching between tizanidine tablets and capsules.
Does the R180 pill make you sleepy?
Yes. Drowsiness is one of the most common tizanidine side effects. Avoid driving and risky tasks until you know how your body responds.
Can you drink alcohol after taking R180?
Avoid alcohol while taking tizanidine. Alcohol can raise tizanidine levels and add to drowsiness, poor coordination, low blood pressure, and other side effects.
Is R180 addictive?
Tizanidine is not a controlled substance. Its abuse potential has not been studied in people. Physical dependence and withdrawal can occur, especially after high doses or long-term treatment. Take it only as prescribed and ask for a supervised taper when treatment is ending.
How many R180 pills can you take in a day?
One R180 tablet contains 4 mg. Tizanidine may be prescribed up to 3 times in 24 hours, with a maximum total of 36 mg. These limits do not tell you how many tablets to take. Take only the number printed on your prescription label, and never add a dose on your own.
Can R180 be used during pregnancy?
Human pregnancy data are limited, and animal studies found developmental harm. Contact the prescriber if you are pregnant, planning a pregnancy, or become pregnant during treatment.
What should you do with an unidentified R180 pill?
Keep it away from children and pets and take it to a pharmacist for identification. Call Poison Control at 1-800-222-1222 if anyone may have swallowed it.
Safe use of the R180 pill
Use R180 only from your own labeled prescription. Take the exact dose, keep food timing consistent, and check every new medicine with a pharmacist. Ciprofloxacin and fluvoxamine have serious interactions with tizanidine. Alcohol and sedating drugs can make drowsiness and low blood pressure worse.
Loose pills should be checked before use. Get urgent help for breathing trouble, collapse, severe allergic symptoms, or extreme sleepiness.
Medical disclaimer: This article gives general information and does not replace advice from a physician, pharmacist, or other licensed health professional. Do not use it to diagnose a condition, identify a pill with certainty, or change a prescription. Seek medical help for symptoms or suspected poisoning.
References
- DailyMed: Tizanidine tablet prescribing information
- MedlinePlus: Tizanidine patient drug information
- Drugs.com: R180 pill identification
- Poison Help: U.S. poison center assistance