Why 5 kg makes this gel cap dangerous
That softgel contained enough vitamin A to meet a human’s needs for days, but scaled down to your cat’s tiny body weight, it’s like drinking the entire bottle. Cats process vitamin A differently than humans — they can’t convert beta-carotene efficiently, so preformed vitamin A hits their system at full strength. At 5 kg, his liver is working with about 1/10th the capacity of an average adult’s.
The gel cap’s oily contents also mean faster absorption than a tablet. Within 30 minutes, significant amounts are already entering his bloodstream, heading straight for hepatic storage. This is why acting now, before symptoms appear, gives the best chance to prevent lasting damage.
Emergency symptoms that escalate fast
First signs often include excessive licking of lips or smacking sounds — nausea setting in as the vitamin A irritates his stomach lining. Vomiting may start within the hour, sometimes with bits of the gelatin capsule visible. More concerning is lethargy progressing to inability to stand, which signals neurological impact.
Cats show joint pain differently than dogs — he might sit hunched with elbows sticking out awkwardly, or refuse to groom his hindquarters. Skin changes appear later; if the inner ear flaps look scaly or his coat seems greasy, the overdose is affecting skin cell turnover.
The critical first 4 hours
Right now, the priority is preventing further absorption from his gastrointestinal tract. Don’t wait for symptoms — by the time he acts sick, a dangerous amount has already entered his system. Vets can administer medications to protect the liver and bind remaining vitamin A, but these work best when given early.
Blood tests now establish baseline liver values, crucial for monitoring progression. Even if he seems okay after vomiting once, vitamin A’s effects are cumulative — his liver enzymes could spike days later without outward signs until damage is significant.
Long-term risks for small felines
One-time large doses can cause acute liver inflammation, but repeated smaller overdoses lead to bony outgrowths on the neck and limbs. At this dose, your cat risks both — the initial assault on his liver today, plus residual vitamin A that will keep releasing from his fat stores over weeks.
Watch for subtle changes like new sensitivity around his neck (difficulty grooming) or hesitation when jumping down from heights. These might appear weeks later as excess vitamin A alters bone remodeling. Kittens are especially vulnerable to growth plate damage from such overdoses.
The step-by-step response, from the first minute to the vet visit, is in our Vitamin A Toxicity in Dogs and Cats emergency guide.