A UTI script can turn 2 mg into a toxic-looking exposure
Ciprofloxacin is ordinary. Fluvoxamine is less ordinary but still sits on OCD and depression lists. Either one next to tizanidine is a labelled contraindication, not a 'monitor BP' hedge.
The 2 mg floor does not become safe because the milligram looks small. A 33-fold AUC rise does not care that Yvessa titled the start tablet.
If both drugs are already on the list, do not take the next Zanaflex. Call. This page is not a taper calculator.
When psychiatry owns fluvoxamine and neurology owns 2 mg
The two clinics must pick a survivor. This desk will not trade OCD control for a floor spasm tablet in an email.
A written hold date for tizanidine during a fluvoxamine restart prevents a quiet overlap at home.
If spasm flares on the hold, neurology needs a different agent, not a sneaked 2 mg.
Patients who 'only take Luvox sometimes' still have the 33-fold story on the days they take it.
Bring both letters to one pharmacist. Split care is how the wall fails.
What a Geneva window should catch before 2 mg leaves
A software flag for fluvoxamine or ciprofloxacin next to tizanidine is worth more than this markup. Ask the counter to look if you collect both packs in one week.
Hospital discharge lists written at 02:00 miss spasm tablets. Read the paper before you swallow the home 2 mg plus a new cipro.
Dental 'something for infection' bags are where fluoroquinolones arrive. Say Zanaflex the way you would say warfarin.
Travel clinics write cipro for traveller diarrhoea in some old habits. That pair is still contraindicated at 2 mg.
If the flag is missed and both were taken, hold tizanidine and call. Do not take a third 2 mg to 'finish the spasm'.
The combination is usually an add-on, not a joint plan
Neurology starts tizanidine. A week later someone treats a UTI with cipro or restarts fluvoxamine for OCD. Nobody opens the spasm leaflet. That is the failure mode this draft exists to name.
Dental and travel clinics write fluoroquinolones. Teach patients to say 'I take Zanaflex' the way they would say an anticoagulant.
Stopping tizanidine for a five-day cipro course still needs a spasm plan. Stopping fluvoxamine to 'make room' for 2 mg is a psychiatry decision, not a markup swap.
This desk will not pick your UTI drug
Many urinary infections can be treated with agents that are not potent CYP1A2 inhibitors. That choice is a prescriber and local-resistance job.
Do not crowd-source a substitute from a forum and keep 2 mg running. Do not stop a needed antibiotic because a markup scared you - call and hold the spasm tablet until someone who has both lists answers.
Levofloxacin and others still sit near the caution list. 'Not cipro' is not an automatic clear.
Inhibitors that are not the two hard stops
The label lists other CYP1A2 players: zileuton, fluoroquinolones other than ciprofloxacin (which is already contraindicated), some antiarrhythmics (amiodarone, mexiletine, propafenone), cimetidine, famotidine, oral contraceptives, acyclovir, ticlopidine. Concomitant use should be avoided unless tizanidine is necessary, then caution.
That is not a free-for-all. It is a weaker sentence than 'contraindicated' and a stronger sentence than 'no interaction'.
Smoking induces CYP1A2. Quitting can raise tizanidine levels. Mention a stop-smoking week at the next visit.
SSRI class is not one CYP story
Fluoxetine 20 mg uses live on another Yvessa plan. Fluoxetine is not the 33-fold fluvoxamine story. Do not paste this wall onto every antidepressant.
If the bottle says Luvox or fluvoxamine, the wall applies. If it says Prozac, read the fluoxetine plan for its own MAOI and interaction rules.
Combination products and hospital 'something for sleep' cups still need names. 'An SSRI' is not a med rec.
The picture is sleep plus a floor-level blood pressure
Expect heavier sedation than the driving note described, plus hypotension and bradycardia. Psychomotor impairment is not subtle in the cipro study.
Do not treat that picture with more coffee or a second 2 mg 'because spasm broke through'. Hold tizanidine and get help.
If the pair was already swallowed, emergency care for collapse or chest pain is 144. Bring both boxes.
Wall rules under the 2 mg lock
- Fluvoxamine: never with tizanidine, including 2 mg
- Ciprofloxacin: never with tizanidine, including 2 mg
- Other CYP1A2 inhibitors: pharmacist plus prescriber before any add
- Sedation note is separate - this page is the enzyme wall
Name both packs if you already overlapped
If cipro and tizanidine were both taken, tell triage both names and times. Sleepiness plus a low pressure is the expected toxic picture, not a mystery virus.
Do not drive yourself if you are already fogged. A household member or an ambulance is safer than pride.
Bring the boxes. A verbal 'some muscle pill' wastes minutes.
Hold further 2 mg until someone who has both lists answers. Do not take a third tablet because spasm flickered in the waiting room.
The 2 mg lock is still contraindicated in the pair. Floor milligrams do not punch a hole in a 10-fold or 33-fold rise.
The last cipro swallow is not an automatic 2 mg morning
Ask when tizanidine may restart. Residual inhibitor is a clinician gap, not a midnight guess.
Restart at the 2 mg floor unless they write your old afternoon extra. Spasm may flare on the hold. That is a clinic problem.
If fluvoxamine is the long-term drug, neurology needs another spasm agent. Do not sneak 2 mg on weekends.
Write the hold and the restart on the same card as the driving note. Split papers are how overlaps return.
What the interaction numbers actually measured
With fluvoxamine, tizanidine serum concentration jumped (Cmax 12-fold, AUC 33-fold). Hypotensive and sedative effects were potentiated. The label says they should not be used together.
With ciprofloxacin, Cmax rose about 7-fold and AUC about 10-fold. Blood pressure fell, drowsiness rose, psychomotor testing worsened. Same sentence: do not combine.
Those fold-changes were measured with single tizanidine doses in the programme. They are not a licence to 'just use 2 mg'. They are the reason 2 mg is still forbidden in the pair.
| Added drug | Tizanidine PK change | Label |
|---|---|---|
| Fluvoxamine | Cmax ~12x; AUC ~33x | Contraindicated |
| Ciprofloxacin | Cmax ~7x; AUC ~10x | Contraindicated |
| Other CYP1A2 inhibitors | Variable rise | Avoid unless necessary; caution |
A 2 mg swallow under a 33-fold rise is not a small adult dose
People bargain with the floor tablet because the milligram looks harmless. The fluvoxamine study did not bargain. Cmax rose about twelve times and AUC about thirty-three. Ciprofloxacin still multiplied AUC about ten times. Those are labelled contraindication numbers, not forum scares.
Hypotension, bradycardia, and psychomotor failure are the picture. Coffee will not reverse them. A third 2 mg in the waiting room will make them worse.
Other CYP1A2 inhibitors sit on a weaker sentence: avoid unless tizanidine is necessary, then caution. Oral contraceptives, some fluoroquinolones that are not cipro, cimetidine, and acyclovir live there. They still deserve a pharmacist look.
Smoking induces CYP1A2. A quit week can raise tizanidine. Mention it.
The driving sibling still applies when the wall is clear. This page is only the enzyme stop so the 2 mg lock is not read as a loophole.
Yvessa files uses notes. It does not clear a tiny exception by email.
Hold 2 mg if either hard-stop drug appears
Keep the parent Zanaflex 2 mg uses plan as the sheet. This draft only marks the CYP1A2 wall so the floor lock is not read as a loophole.
Collapse, severe dizziness, or an unresponsive sleepy state: 144. Bring both packs.
Sources
- FDA Zanaflex - contraindication with fluvoxamine and ciprofloxacin; other CYP1A2 caution list.
- DailyMed Zanaflex - fluvoxamine Cmax 12x / AUC 33x; ciprofloxacin Cmax 7x / AUC 10x.
- Label counselling - tell clinicians when any medicine starts or stops.
Checked against the current label and reviewed by Dr. Amélie Laurent. See Survey, Draft, Peer-check, Stamp.