FortiFlora is a powdered probiotic supplement made by Purina for cats. The current U.S. feline label directs owners to give one packet daily, or as directed by a veterinarian, and says the product is intended to assist in managing occasional diarrhea. Purina’s FAQ says no negative side effects have been observed or are expected. Independent safety data on the product is limited, and the label tells owners to stop and consult a veterinarian if the cat’s condition worsens or does not improve.
What FortiFlora for cats is
FortiFlora is sold as a feline-specific powder. Each packet is a 1.0 g sachet, and the label describes it as a probiotic health supplement for cats. It is not a medication, and it is labeled for cats only, with a warning against human consumption.
| Label item | What the current U.S. feline label states |
|---|---|
| Product form | Powder supplement, supplied in 1.0 g sachets |
| Active ingredient 1 | Enterococcus lactis SF68 at 1 × 108 CFU per sachet |
| Active ingredient 2 | Taurine, 5 mg per sachet |
| Inactive ingredients | Liver flavor and yeast |
| Labeled use | To assist in managing occasional diarrhea |
| Species | Cats only |
A note on the strain name
The current label calls the organism Enterococcus lactis SF68. The 2011 and 2017 clinical reports discussed below use the older name Enterococcus faecium SF68 for what appears to be the same strain. If you compare FortiFlora with older literature, expect to see both names. Use the name printed on the package you are buying when checking product details.
Dosage and how to give it
The current U.S. feline label reads: “Administer one packet daily or as directed by your veterinarian.” Several points follow from that wording:
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- Number 1 vet-recommended cat probiotic brand to support digestive health (online survey among all US vets who indicated brand as one of 1-3 brands recommended Q4 2025).
- For Cats of All Ages: Purina Pro Plan Sensitive stomach cat food supplement for the dietary management of kittens and adult cats with cat diarrhea.
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- Trusted Brand: FortiFlora digestive probiotics for cats are developed in collaboration with Purina nutritionists, researchers and veterinarians.
- The dose is one packet per day, not a weight-based amount. The label does not scale the dose to the cat’s body weight, so a larger or smaller cat receives the same packet.
- The label does not state a treatment duration. It does not say how many days to continue. Your veterinarian’s direction is the reference point for how long to give it.
- Veterinary direction overrides the default. The label gives the packet-a-day instruction as the default and explicitly defers to a veterinarian’s instructions.
Before starting, the label recommends a veterinary examination. A supplement given without an exam means the cause of the diarrhea has not been identified.
Side effects and cautions
Side effects need to be considered in two parts: what the manufacturer says about its own product, and what independent sources have established. They are not the same thing.
The manufacturer’s statement on side effects
Purina’s FAQ states that FortiFlora has no negative side effects observed or expected. That is the manufacturer’s own statement. It is not an independent finding, and it does not mean adverse reactions cannot occur in any individual cat. The sources reviewed do not provide a reliable incidence rate for side effects or an exhaustive independent adverse-effect profile. In practice, this means a cat’s reaction should be judged by the owner and veterinarian, not by the absence of a published warning.
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Pregnancy and breeding
The feline label states: “Safe use in pregnant animals or animals intended for breeding has not been proven.” If the cat is pregnant, nursing, or being bred, talk to your veterinarian before giving FortiFlora. The label does not establish safety in these cats, so the decision rests on veterinary judgment.
When to stop and call a veterinarian
The label instructs: “If animal’s condition worsens or does not improve, stop product administration and consult your veterinarian.” Apply that instruction in two situations:
- The cat’s diarrhea gets worse while on the product.
- The diarrhea does not improve, or keeps coming back, after the product is given as directed.
A probiotic is not a substitute for veterinary assessment. Diarrhea can have many causes, and the cited studies do not show that FortiFlora addresses every cause. Contact a veterinarian promptly if diarrhea is accompanied by vomiting, blood in the stool, lethargy, loss of appetite, or signs of dehydration, or if the cat is a kitten, a senior, or has an existing illness.
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- Nature + Science in Every Scoop: Probiotic, prebiotic, FOS, and fiber-rich pumpkin and carrot make this cat diarrhea solution a complete formula for firmer stool and healthy digestion.
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What the clinical studies show
Two randomized controlled studies are the main published evidence on the strain. Each one answers a narrow question, and neither establishes a general treatment effect for diarrhea in all cats.
2011 shelter study (Bybee, Scorza, and Lappin)
A double-blind, placebo-controlled study published in the Journal of Veterinary Internal Medicine enrolled 217 shelter cats and 182 shelter dogs. In the cats, diarrhea lasting at least two days occurred in 7.4% of those receiving SF68 and 20.7% of those receiving placebo (P = .0297). This is a statistically significant difference in a shelter population. It does not show how the product performs in a single household cat, and it does not show that FortiFlora prevents or treats diarrhea from every cause.
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2017 antibiotic-associated diarrhea study (Torres-Henderson et al.)
A 2017 randomized controlled study examined cats receiving amoxicillin-clavulanate. Total diarrhea scores over days 1–11 were lower in the SF68 group than in the placebo group (P = 0.0058). This supports a possible benefit in the antibiotic-associated setting that was studied. It does not establish a universal effect in cats with diarrhea from other causes.
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| Study | Animals and setting | Outcome measured | Reported result | What it does not show |
|---|---|---|---|---|
| Bybee, Scorza, and Lappin, 2011, Journal of Veterinary Internal Medicine | Double-blind, placebo-controlled; 217 shelter cats and 182 shelter dogs | Diarrhea lasting at least two days (cats) | 7.4% SF68 vs 20.7% placebo; P = .0297 | Results in a shelter setting; not a guarantee for an individual household cat or for diarrhea from every cause |
| Torres-Henderson et al., 2017, randomized controlled study indexed in PubMed | Cats receiving amoxicillin-clavulanate | Total diarrhea scores, days 1–11 | Lower in SF68 group than placebo; P = 0.0058 | A universal treatment effect; benefit beyond the antibiotic-associated setting studied |
Limits of the evidence
The published evidence is limited in three ways. First, the studies are narrow: one examined shelter animals and one examined cats on a specific antibiotic. Second, the outcomes are specific, such as diarrhea duration and diarrhea scores, rather than a broad measure of health. Third, no independent regulator or veterinary society statement on this specific product was identified. The label directions and FAQ statement are manufacturer instructions, not independent clinical guidance. Read them as the product’s official directions, and let your veterinarian interpret them for your cat.
Comparing probiotics for cats
If you are considering a different probiotic for your cat, the word “probiotic” alone does not make two products interchangeable. Compare the following:
- The named strain and the amount per dose (for FortiFlora, Enterococcus lactis SF68 at 1 × 108 CFU per 1.0 g sachet).
- The species the label names and the intended use the label describes.
- The dosage form and the administration directions.
- Any clinical evidence tied to the specific strain and the condition your cat has.
- The manufacturer’s cautions, including pregnancy and breeding guidance.
A product with a different strain, dose, or formulation may not carry the same evidence, even if it is also sold as a feline probiotic.
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