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What is Antibiotics Allergy?

Antibiotics are used in cats to treat a variety of illnesses. Antibiotics treat infections, as well as bacteria and yeast. Although these are quite effective in treating a cat’s illnesses, there are times in which cats may show an allergic reaction to a specific antibiotic. As with other allergies, a cat’s immune system may be very sensitive to a specific antibiotic and treat the medication as a foreign substance that must be fought. As these medications are being fought by the immune system, a cat may show certain symptoms that may be a cause for concern. 

Antibiotics also have a variety of side effects that occur when taking them. Side effects from antibiotics are usually not a cause for concern if they are mild. When a veterinarian prescribes a cat an antibiotic, he will communicate with the pet owner the possibility of side effects and when to immediately stop giving the medication. An allergy, however, is different, since the cat is actually having a reaction to the medication due to an over reactive immune system rather than having a typical side effect. Side effects and an allergy may present themselves in similar forms, thus, if a cat is showing any severe symptoms, it is very important to call a veterinarian.

Antibiotics allergies in cats are due to cats being allergic to specific antibiotics prescribed by a veterinarian to fight an existing infection. Allergic reactions to antibiotics can be very mild to severe, and need medical attention.

Symptoms of Antibiotics Allergy in Cats

If your cat is having an allergic reaction to an antibiotic, he may present a few or several symptoms. If you feel your cat is having an allergic reaction contact your veterinarian immediately. Symptoms may include: 

  • Rashes
  • Itching
  • Swelling
  • Narrowing of the airways
  • Diarrhea
  • Dehydration
  • Inability to breathe
  • Vomiting
  • Fever

Types

There are several different types of antibiotics which cats may be given for a variety of infections. Although they are considered safe, it is important to monitor your cat when taking an antibiotic just in case he is allergic. Different types are:

  • Penicillin
  • Cephalexin
  • Enrofloxacin
  • Trimethoprim-sulfa
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Causes of Antibiotics Allergy in Cats

Causes of antibiotics allergies in cats happen for several reasons and they may be confused with typical side effects. Specific causes may include:

  • Interference with other medications
  • Overdosing or dosages being too close together
  • Histamines are released within the body 
  • Immune system fighting the antibiotic as a “foreign invader”
  • Sensitive immune system
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Diagnosis of Antibiotics Allergy in Cats

If you are administering antibiotics given by your veterinarian to your cat and he is showing a reaction, contact your veterinarian. Do not give your cat another dose of the antibiotic until you speak to your veterinarian.

Your veterinarian will take a close look at your cat’s symptoms and will ask you questions about when his symptoms began and the severity of those symptoms. He will want to know how many doses of antibiotics were given before he began showing signs of an allergic reaction. He may also ask if you have fed him any different types of food or if your cat has been exposed to anything different or unique which could cause an allergic reaction. Your veterinarian will perform a complete physical examination of your cat, including bloodwork, urinalysis, and any other primary tests which he feels are necessary. 

If your cat is having a skin reaction, your veterinarian may choose to scrape a tiny bit of dry skin and send it to the laboratory for a diagnosis. Typically, your veterinarian will forgo this action because of the fact your cat began exhibiting a reaction soon after beginning the antibiotic. Your veterinarian may suggest that you stop giving your cat the antibiotic and see if any allergic reaction he is having dissipates.

Your veterinarian may also suggest a different type of antibiotic for your cat so he can continue to recover from any infection he may have. He may also suggest another medication for the time being in order for your cat to begin feeling better from any allergic reaction he is suffering from.

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Treatment of Antibiotics Allergy in Cats

Treatment for an allergic reaction to an antibiotic will begin once your veterinarian has determined your cat’s diagnosis. Treatment methods may include:

IV Fluids with Medication

If your cat has had diarrhea or vomiting due to an allergic reaction, your veterinarian may administer IV fluids to help rehydrate him and restore any lost electrolytes. IV fluids will also encourage urination and proper kidney function and help the antibiotic make its way out of his system so he can recover. An antihistamine may also be added to the IV to help fight the allergic reaction.

Wash and Rinse

If your cat is scratching or biting at his skin and has any inflammation or irritation of his in due to a rash or hives, your veterinarian may give him a bath and a mild detergent to help with any skin inflammation or discomfort. This may help calm the skin down and give your cat some relief.

Avoiding Future Dosages

Your veterinarian will want you to stop any future dosages of this antibiotic. Whether or not he replaces the antibiotic with another will be his decision and will depend on your cat’s infection; your veterinarian may find an alternative solution to medicating your cat so he can continue to recover from any infection he may have. Once future dosages are avoided, your cat should not have any more allergic reactions. It may take a few days for the medication to leave his system.

Monitoring

If your cat’s allergic reaction is severe, your veterinarian will treat him symptomatically. He may want to keep him overnight to monitor him to be sure his breathing is stabilized.

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Recovery of Antibiotics Allergy in Cats

Once you are able to take your cat home, your veterinarian will give you instructions and tell you what to watch for in terms of new symptoms. Since you are no longer giving your cat the offending antibiotic, your veterinarian may have prescribed a different medication. Once you give your cat the different medication, it will be important to understand all side effects of the medication, to give exactly the prescribed dosage, and watch for any other allergic reactions which may occur. If you see any other reactions, contact your veterinarian immediately.

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Antibiotics Allergy Questions and Advice from Veterinary Professionals

Need pet health advice? Ask a vet

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Tabby

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Three Years

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Unknown severity

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Unknown severity

Has Symptoms

Swollen Eyes, Loss Of Appetite,

My cat recently had an exploratory surgery and was put on Veraflox, famotidine, and cyproheptadinr

Sept. 29, 2020

Owner

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Dr. Michele K. DVM

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0 Recommendations

Thank you for your question. Depending on the findings during the exploratory surgery, there may be an explanation for what you were describing. Since I don't know very much about your cat's situation or why the exploratory happened, it would be best to call the veterinarian that was taking care of him, let them know what is happening with him, and see what they suggest as far as treatment goes. I hope that he is okay and feels better soon.

Oct. 1, 2020

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Calico cat

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6 weeks

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Unknown severity

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Unknown severity

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Lethargic, Sleeping, Have To Force Feed With Bottle Cause She Has No Appetite Suddenly

Worried about our kitten she lost her mom so we have been bottle feeding her and trying to introduce dry food. She suddenly this morning not wanting to eat/drink and is tired and lethargic.

Sept. 26, 2020

Owner

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Dr. Michele K. DVM

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Thank you for your question. I apologize for the delay in my reply, this venue is not set up for urgent emails. It would be best to have your pet seen by a veterinarian, as they can examine them, see what might be going on, and get any testing or treatment taken care of that might be needed.

Oct. 19, 2020

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Domestic Shorthair - Cat

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Fifteen Years

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Unknown severity

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Unknown severity

Has Symptoms

Strange Meowing

This is her first day on this medication for a staph infection in her bladder. A few hours after her second dose, she’s made a few strange meows like she’s very uncomfortable. She was playing like a lunatic after the first strange noise, and still very happy to be pet and purring. She wanted more food and acted very ravenous, so I gave her some extra soft food, thinking maybe she was nauseous. Wondering if this is common or if I’m taking a trip to the emergency vet this evening.

July 10, 2020

Owner

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Dr. Michele K. DVM

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If you just recently had her seen by a veterinarian, and she was otherwise healthy, you may be okay to keep a close eye on her. That medication can make cats a little nauseous, you're right, and it may be best to feed her a bland diet of boiled white chicken and boiled white rice for a couple of days to see if that settles her stomach. If she continues with the weird Behavior oh, it would be a good idea to have a recheck with your veterinarian, as soon as they are open. I hope that all goes well for her!

July 10, 2020

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Lila

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Siamese

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5 Years

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Moderate severity

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Moderate severity

Has Symptoms

Swollen Eyes
Redness In Eyes
Irriated Eyes

My cat (siamese, 5Y8M old, female, spayed, indoor, healthy weight) seems to have periodic conjunctivitis in her eyes. I was recently prescribed an eye gel that includes chloramphenicol and the day after applying this gel to her eyes, it seems that her eye infection has gotten worse. She blinks more often, her eyes are more swollen and red than before. The third day also shows the same reaction. The vet said she should be getting better after a few days so I am wondering if these signs are a sign of an allergic reaction to the medication or if she may have viral conjunctivitis and not bacterial?

Sept. 8, 2018

Lila's Owner

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Char

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Russian White

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9 Years

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Moderate severity

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Moderate severity

Has Symptoms

Excessive Licking
Scratching Above Eyes
Biting At Paws, Over Grooming

Char has been on Clavamox for two weeks due to gingivitis/a gum infection. She’d been overgrooming her paws, and scratching above her eyes to the point of scabs/bleeding but the vet didn’t mention this could be a possible side effect of medication. After getting her teeth cleaned four days ago, we’ve noticed she’s groomed patches on her belly, legs and paws down to the pink and is frequently licking/biting, and scratching. The Clavamox course is now done - what will help soothe her skin or help flush out the allergy? Thanks in advance for your best advice.

July 30, 2018

Char's Owner

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2 Recommendations

Itchy skin is a known side effect of Clavamox (amoxicillin/clavulanate) and should wear off with time if this is the cause; there is no specific way to flush the Clavamox out of the body but try to prevent Char from itching and licking herself and bathe any wounds or scratches she may have inflicted on herself. If there is no improvement in the itching and licking you should visit your Veterinarian for a follow up to be on the safe side and they may prescribe something to help with the itching. Regards Dr Callum Turner DVM “As with any medicine, CLAVAMOX may cause problems. Some pets may have an allergic reaction to this kind of medicine. Symptoms of an allergic reaction include swelling of the face, itchy skin, hives, vomiting, diarrhea or breathing problems. Allergic reactions may be serious, and may happen very quickly. If you think your pet is having an allergic reaction to the medicine, call your veterinarian right away.” www.zoetisus.com/contact/pages/product_information/clavamox.aspx

July 30, 2018

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Chloe

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DOMESTIC

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11 Years

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Moderate severity

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No Eating / Drinking Lethargic

Hi - My 11 year old Chloe went for a Welllness check a week ago. Chloe is a beautiful, heathy, girl. She passed with flying colors, except the Vet discovered she had an ingrown toe-nail. The nail was cleaned up and she gave her an injection of Convenia, and sent us home with Chloe to wear a cone etc...Well the cone was disastrous for her, and we decided to let her go cone free supervised since we would be close to home for several days. Within 48 hours she stopped eating and was drinking little. By the 4th day after her visit we took her back to the vet and they gave her fluids (via injection) ; anti-nausea injection and an appetite stimulant (pill form). Chloe showed a minimal sign of improvement, but essentially in the days that followed she declined and was eating , drinking nothing. We went back to the vet on day 6 and repeated everything (Chloe would not let me give her the pill for appetite stimulant ), but no improvement. I took her back last night and they have kept her, giving IV fluids, for hydration, and stimulate her appetite and monitoring. The Vet reported this morning that she ate an entire small tin of food and some kibble!....After a sleepless nite I was so relieved. However, not entirely convinced she is out of the woods yet...They want to keep her another 24 hours....I am good with this but the whole experience has been terrifying!...I never would have agreed to giving her the Convenia had I known this would happen. The Vet stated they have never seen this before although have admitted her reaction is likely due to the injection. They have contacted the manufacture, who now have opened a file on Chloe....I need some assurances she will recover...and do you have any suggestions of how I can help her along once she is home...Probiotics?..Thank you so much! - Mary

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Ohdeey

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Maine Coon

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1 Year

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Moderate severity

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Moderate severity

Has Symptoms

Sneezing
Drooling
Breathing Difficulty
Not Drinking Water
Foaming At The Mouth

So I have a cat that gets sick really easy they put her on doxycycline and within two days we saw improvement. They told us since we have two other cats that there was enough if needed. Well my Maine coon started sneezing and had a fever so I gave him a dose now I know that it’s bitter tasting but he immediately started foaming at the mouth and drooling. I gave him the next dosage 12 hours after as directed and this time gave him peanut butter after. The foaming didn’t happen and he seemed fine but when I got home he is now sneezing even more and foaming and drooling and seems to be having a harder time breathing. We have not seen improvement like in the other cat. Could he be allergic? Oh also he is rubbing his eye/nose with his paw a lot.

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Pearl

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Persian

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10 Months

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Serious severity

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Serious severity

Has Symptoms

Fever, Lethargic

Pearl my 10 months old kitten is unwell these days not having proper food , feeling lethargic when took to vet she was given antibiotics called zedox as a 12 day course it’s been 8 days she started eating a bit but fever is persistent, she was gone through blood test and found everything is normal ,vet suggested to go through PCR test to find viral infections, Any suggestions on this ??

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Rano

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Bengal cat

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9 Months

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Serious severity

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pill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filled

Serious severity

Has Symptoms

Redness
Redness Hairloss
Redness Hair Loss

My cat is 9 months old and she caught a fever.my vet gave him 3 injections per day and her treatment done in 3 days. she was active after treatment but not eating anything.Yesterday i saw a allergic reaction(red patch) around his tail area and its spreading all over his belly under side. some pox type granules on her nose also.My pet refuse to check and treat her :( don't know what to do now cuz i'm living in a town where only single vet live and he refused to help my cat. :( :( kindly suggest me something.

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Luna

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domestic short-hair

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1 Year

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Mild severity

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0 found helpful

pill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filled

Mild severity

Has Symptoms

Scratching Neck And Ears,
Inflammation On Ears
Excessive Licking Around Tail

About 2 weeks ago my vet prescribed amoxicillin to treat an upper respiratory infection, as well as an immune system supplement and probiotic powder. 3 days ago I noticed a hot spot on the base of her tail. At first I thought it was a reaction to fleas although I hadn't seen any, and gave her a flea bath that I had used previously with no issues. She now has inflammation on her ears and her neck seems to be really itching. There are some knots from her excessive scratching. I've kept an e-collar on her most of the time to avoid making the hot spot worse and it is healing, but every time I give her a break she immediately starts licking there and scratching her neck, almost compulsively. I haven't changed any chemicals in the house, or her food, and I've ensured that the air filter to my AC unit is clean. She seems to be getting worse and the only variable I can think of right now is the antibiotics, although she's been off them for a little over a week.

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