Urinary Drug & Supplement Compendium
Evidence over reviews — drugs and supplements sorted by research, track record and real usage in this app.
How to read the grades
- Feline evidenceFeline clinical evidence (RCT / prospective)
- Limited evidenceSmall/observational feline studies, or dog evidence
- ExtrapolatedExtrapolated from other species / in-vitro
- UnestablishedEvidence not established
Pain relief (buprenorphine·NSAIDs)
The first line of cystitis care — make the bladder stop hurting first
Limited evidence
Drug
BOTTOM LINE
For a cat with cystitis signs, pain relief is not an extra — it is the core of treatment, the first step in breaking the loop where pain feeds stress and stress feeds cystitis.
More than half of feline cystitis is idiopathic (FIC) — no bacteria, no stones — yet the bladder wall genuinely hurts from inflammation and nerve sensitization. That is why international guidance puts pain relief first in the acute phase; avoiding the litter box, peeing in odd places and frequent licking can all be pain signals. Buprenorphine, an opioid absorbed through the mouth lining, has long been used in cats; NSAIDs also tackle inflammation but strain the kidneys in cats that drink little or have kidney disease, so your vet chooses. Above all, never share human painkillers from your cabinet.
FACTS
- Research
- Pain control in acute idiopathic cystitis (FIC) is a standard recommendation of the international consensus (iCatCare 2025) — few large feline trials per drug
- Track record
- Buprenorphine used in cats for 20+ years · feline-licensed NSAIDs (meloxicam, robenacoxib) in use
- Caution
- Never give human painkillers — acetaminophen (Tylenol) can be fatal to cats · NSAIDs risk the kidneys in dehydrated or kidney-disease cats; only prescribed dose and duration · if no urine comes out, go to the ER instead of medicating
Prazosin (urethral relaxant)
A plausible mechanism, no difference in trials — a lesson in reading evidence
Extrapolated
Drug
BOTTOM LINE
There is currently no evidence that it prevents reobstruction in previously blocked males. If it was prescribed, do not stop on your own — confirm the reason and the re-evaluation point with your vet.
Males that were blocked and unblocked re-block fairly often (36% in one study), so prazosin, said to relax the urethra, was long a standard discharge drug. Critics noted that the lower urethra, where blockages form, has more of a different muscle type than the smooth muscle this drug acts on — and a 2021 placebo-controlled trial indeed found no difference in reobstruction. The 2025 international guideline therefore does not recommend routine use. This card is a clear example that "the mechanism sounds right" and "it helped patients" are different claims.
FACTS
- Research
- In a 2021 randomized placebo-controlled trial (65 cats analysed), reobstruction rates did not differ significantly between prazosin and placebo · iCatCare 2025 does not recommend routine use
- Track record
- Routinely added at discharge for decades · being re-evaluated after the 2021 trial and the 2025 guideline
- Caution
- Can lower blood pressure, causing weakness · caution with other blood-pressure drugs · if urine stops again, do not wait on the drug — go to the clinic now
Gabapentin (pain·stress)
Shown in a trial to ease the stress of vet visits
Limited evidence
Drug
BOTTOM LINE
A reasonable option to discuss for cats whose flare-ups follow vet visits or travel, or who seem to have chronic pain. It does not cure cystitis itself.
Idiopathic cystitis is tangled up with the stress-response system, not just the bladder, so many cats flare after vet visits, travel or household changes. Gabapentin calms over-sensitized nerve signalling; in a feline placebo-controlled trial, one dose before the visit lowered stress scores during transport and the exam. It is used to ease recheck days and for suspected chronic pain. Direct trials showing it prevents cystitis flares are still lacking, and sleepiness and wobbliness are common, so try the first dose at home.
FACTS
- Research
- In a feline randomized placebo-controlled crossover trial (van Haaften 2017), a single 100 mg dose before the visit lowered transport and exam stress scores · trials on cystitis pain itself are limited
- Track record
- A human nerve-pain drug since the 1990s · widely used in cats for pre-visit calming and chronic pain
- Caution
- Sleepiness and wobbliness are common (usually hours) · lingers longer with kidney disease, so doses need adjusting · some human liquids contain xylitol — use the product your vet specifies
Amitriptyline (chronic recurrent cystitis)
The last card, played when everything else has failed
Limited evidence
Drug
BOTTOM LINE
Not a drug for the acute phase. For severe cases that still flare several times a year despite thorough environment, wet-food and stress work, it is an option to trial with your vet over months.
Amitriptyline has been used in chronic recurrent cystitis because it dampens pain signalling, anxiety and the bladder's histamine response together. In small studies of severely recurrent cats treated for months, some improved, but a short-term placebo-controlled trial showed no difference. It takes time to work and side effects such as sleepiness and weight gain are common, so today it is a last card after other measures have been used fully. If you start, agree in advance on how long you will assess benefit and side effects.
FACTS
- Research
- In an open study of 15 cats with severe recurrent FIC (Chew 1998), 9 (60%) stayed sign-free for 12 months · a 7-day placebo-controlled trial (Kraijer 2003, 24 cats assessed) found no difference · no large trials
- Track record
- A human antidepressant since the 1960s · used off-label in cats for chronic cystitis and behaviour problems
- Caution
- Sleepiness, weight gain and less grooming are common · fewer urinations raise a theoretical stone risk · check liver values · do not stop abruptly
Antibiotics (bacterial cystitis)
Right only when bacteria are confirmed — most cystitis has none
Feline evidence
Drug
BOTTOM LINE
A sure treatment when a urine culture confirms bacteria. But most cystitis in young cats is idiopathic with no bacteria, so reflexively repeating "cystitis = antibiotics" leaves resistance without benefit.
The biggest misconception about feline cystitis is that it is a bacterial infection. In cats under 10, most cystitis is idiopathic, with neither bacteria nor stones; bacterial cystitis is a minority — whereas older cats and those with kidney disease, diabetes or hyperthyroidism have dilute or sugary urine and more infections. So the fork in the road is a culture of urine taken straight from the bladder by needle. If bacteria are confirmed, use an antibiotic matched to sensitivity; current guidance says 3–5 days is enough for simple cystitis. Bacteria without symptoms are, as a rule, not treated.
FACTS
- Research
- Treating bacterial cystitis is established medicine · ISCAID 2019: sporadic bacterial cystitis is treated for 3–5 days; bacteria without symptoms are not treated
- Track record
- Amoxicillin-class drugs for 50+ years · ISCAID animal urinary-infection guidelines 2011, 2019
- Caution
- Culture and sensitivity (bladder-tap sample) is the gold standard · finish the prescribed course; do not stop early · older cats and those with kidney disease or diabetes have more infections, so culture matters more
Stone-recurrence drugs (potassium citrate·thiazides)
For calcium oxalate stones that will not dissolve — a backup when diet is not enough
Limited evidence
Drug
BOTTOM LINE
Drugs to consider with your vet when calcium oxalate stones return within a year despite water and diet management. Not something to start right after a first stone.
Of the two big feline stone types, struvite can be dissolved with diet, but calcium oxalate cannot — removal and prevention are all there is. First come water (urine specific gravity under 1.030) and a diet that avoids over-acidifying (urine pH 6.5–7.5); drugs are added only for repeated recurrence. Thiazide diuretics lowered oxalate supersaturation in a feline study, but in healthy cats; potassium citrate shifts urine toward alkaline and adds stone-inhibiting citrate, but has no feline controlled study. Both are backup cards "to consider with frequent recurrence."
FACTS
- Research
- Thiazide (hydrochlorothiazide): in healthy cats (Hezel 2007) calcium oxalate supersaturation (RSS) fell about 65%, though 24-hour urine calcium did not · potassium citrate: no feline controlled study · ACVIM 2016 suggests considering them for frequent rec
- Track record
- Decades of use in human stone prevention · mentioned as options for cats in the ACVIM 2016 consensus
- Caution
- Thiazide: recheck potassium, calcium and kidney values; watch hydration · potassium citrate: adjust to the urine pH target (6.5–7.5); beware excess potassium depending on kidney function · not for struvite stones
Glucosamine·GAGs (Cystaid etc.)
The poster child of "bladder-lining support" — no different from placebo in a trial
Extrapolated
Ingredient
BOTTOM LINE
Not harmful to give, but there is no evidence it prevents flare-ups. The same money and effort are better spent on wet food, water and environment changes.
From the observation that the bladder's protective lining (GAG layer) is thin in idiopathic cystitis came the theory that feeding glucosamine, its building block, would restore it — and many pet bladder supplements followed. Yet in a placebo-controlled trial randomizing 40 cats with recurrent cystitis, glucosamine and placebo did not differ, and interestingly both groups improved — likely because many owners fed more wet food at the same time. This card is a clear example that "it got better" does not mean "thanks to this product."
FACTS
- Research
- In a randomized double-blind placebo-controlled trial of 40 cats with recurrent FIC (2004), N-acetylglucosamine did not differ from placebo on clinical measures — both groups improved
- Track record
- Grew from the bladder-lining GAG-defect theory (1990s–) · widely sold as pet bladder supplements
- Caution
- Beware "it got better after we gave it" stories — cystitis often settles on its own, and diet or environment usually change at the same time · check full labels on blends
Cranberry
A human UTI folk remedy — aimed at a different target than germ-free feline cystitis
Extrapolated
Ingredient
BOTTOM LINE
At most worth discussing for older cats with repeated bacterial cystitis; no basis to expect help with idiopathic cystitis in young cats.
Human research suggesting cranberry proanthocyanidins stop E. coli from clinging to the bladder wall made it a famous UTI-prevention supplement. But most feline cystitis is idiopathic, with no bacteria, so the target is different from the start, and no clinical study shows benefit in cats. Cranberry also contains oxalate, so it is safer avoided in cats with a history of calcium oxalate stones. For repeated bacterial cystitis, the first step is a culture and a look for the underlying cause (kidney disease, diabetes and so on).
FACTS
- Research
- No feline clinical study · extrapolated from lab and human research suggesting proanthocyanidins block E. coli from sticking to the bladder wall
- Track record
- A human UTI folk remedy for 100+ years · common in pet bladder blends
- Caution
- Contains oxalate — safer to avoid in cats with calcium oxalate stones · tends to acidify urine · beware sugar and additives in juices and concentrated human products
Calming ingredients (alpha-casozepine·L-tryptophan)
Support for stress-linked cystitis — no substitute for fixing the environment
Limited evidence
Ingredient
BOTTOM LINE
A gentle add-on alongside environment changes for cats whose flare-ups seem stress-triggered. Do not expect it to prevent recurrence on its own.
Idiopathic cystitis tends to strike cats with a sensitized stress-response system and often returns after a move, a new family member or litter-box trouble. That is why the core of international guidance is environment change (MEMO — litter boxes, separate resources, play). Alpha-casozepine, derived from milk protein, reduced anxiety in a small placebo-controlled feline study, and L-tryptophan is paired with it as a serotonin building block. Stress-care prescription diets containing them have been studied, but no trial shows the ingredients alone prevent cystitis flares — think of them as a helper to environment changes.
FACTS
- Research
- Alpha-casozepine (from milk protein): a 56-day placebo-controlled trial in 34 anxious cats (Béata 2007) significantly improved anxiety scores · direct evidence in idiopathic cystitis comes only from prescription diets containing it
- Track record
- Sold as pet supplements (e.g. Zylkene) since the 2000s · included in some urinary "stress" prescription diets
- Caution
- Effects are mild and build over weeks · check for duplication if a prescription diet already contains them · first fix environmental causes — litter-box number and location, multi-cat tension
Feline pheromone (Feliway)
Making home smell "safe" — a trend in trials, not yet proof
Limited evidence
Pet product
BOTTOM LINE
A helper worth adding in homes where changes like a move or a new family member trigger flare-ups. The evidence is too weak to rely on it while litter-box and resource problems remain.
The pheromones cats leave when they rub their faces signal "this place is familiar and safe." The idea behind Feliway, a synthetic version, was that lowering stress at home might reduce stress-linked idiopathic cystitis; a small placebo-controlled pilot trial showed a trend toward fewer flares, but it was not statistically confirmed. It is nearly harmless and may help during big changes, so it is used as a helper — but it cannot replace fixing root causes such as litter-box number and location or multi-cat conflict.
FACTS
- Research
- A small placebo-controlled pilot trial in idiopathic cystitis (Gunn-Moore & Cameron 2004) showed a trend toward fewer episodes, without statistical significance
- Track record
- Synthetic facial-pheromone products since the late 1990s · diffuser and spray forms
- Caution
- Put diffusers in the rooms your cat uses most, not behind furniture · judge effects over weeks · odourless to people and other pets
This compendium summarizes published research and anonymous app statistics for reference. Always discuss starting, stopping or dosing with your vet.