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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

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

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.

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.

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.

Antibiotics Allergy Questions and Advice from Veterinary Professionals

Sepet
Main Coone
10 Months
Mild condition
0 found helpful
Mild condition

Has Symptoms

Lethargic

Medication Used

antibiotic

My 10 month old cat is diagnosed with flu.. despite of that my cat was still very active and playful until i brought my cat to see the vet and was given antibiotic via infiltration.. the next day my cat suddenly look sick.. he was lying down whole day asleep, the flu didn’t get any better. Im not sure if my cat is allergic to the antibiotic given or not. Please help

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Tito
Maine Coon
Thirteen Years
Serious condition
0 found helpful
Serious condition

Has Symptoms

Diarrhea

8 weeks ago the vet gave my cat an antibiotic injection to treat a suspected skin infection. From that day forward he has had diarrhea that is clay like in color. I took him back to the vet and I was given powder probiotics - that didnt work. Then I have had him on prescription royal canin wet food gastro extra energy and he STILL has diarrhea. HELP!!!!

Dr. Michele King, DVM
Dr. Michele King, DVM
1606 Recommendations
I'm sorry that Tito is having this problem. Some antibiotics will cause a short term GI upset to some cats, but they don't tend to go on for that long, and tend to respond to therapy quite well. Since he isn't improving with the therapy that should have helped him, it would be a good idea to call your veterinarian, as they examined him and know more about what is going on with him, and let them know that he still has diarrhea, and see what the next step might be.

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Alizee
domestic short hair
10 Years
Serious condition
0 found helpful
Serious condition

Has Symptoms

none
Depression, lethargy,apetite low
Depression
Lethargy

Medication Used

none

Hi, my 10 year old cat was about 5 days ago taken to the vet because of increased licking of her belly area. Vet on visitation coukd not feel any abnormalities but found her a high fever of 39.8 degrees celcius. A blood test was performed were all values were normal other than high glucose,HCT and reticulocytes. She was give toffedine for her fever and marbocyl. I was also given a prescription of 1 marbocyl 20mg per day. The next day my cat started acting lethargic, no apetite and would even drop food from her mouth while chewing. Took her to vet chevk up resulted that she had an allergic reaction to marbocyl, pupils would not contract to light etc. she was give steroids (dexafort). Her apetite improved but she is still very lethargic that is 24 hrs after dexafort and about 40 hrs from her last marbocyl which i duly stopped.cat suffers from nothing else, what is your advice as to why she is depressed and lethargic, thanks.

Dr. Michele King, DVM
Dr. Michele King, DVM
1606 Recommendations
Thank you for your email. I'm sorry that she is having these problems. Without examining her, I can't really comment on why she is depressed and lethargic - that is a possible but unusual reaction to marbofloxacin, and those signs should continue to improve as the drug is metabolized from her body. She may need continued supportive care while that happens, and if she doesn't continue to improve, you should follow up with your veterinarian, as the lethargy may be related to the original problem that was causing her fever. I hope that she is okay!

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Sammy
Domestic shorthair
12 Years
Mild condition
0 found helpful
Mild condition

My cat (12yrs) received a shot of Convenia and was prescribed Metacam after a leg injury.
That evening, I noticed a couple of sneezes. The following day I noticed a few more sneezes. No discharge.
Should I be concerned?

Dr. Michele King, DVM
Dr. Michele King, DVM
1606 Recommendations
Thank you for your email. It is possible that Sammy is having a mild flare up of viral disease caused by the stress of the injury and the visit to the veterinarian. If his sneezing worsens, or he develops any discharge, or he stops eating, he should be seen by a veterinarian, but typically these infections are self-limiting over a few days.

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Tanny
Calico
1 Year
Mild condition
0 found helpful
Mild condition

Has Symptoms

heavy breath

Medication Used

Amoxicillin

Took my 3 cats to the vet today because of a chronic diahrrea case (in all of them) the vet applied each cat a shot of amoxicillin. 2 of them came home and had no side effects but one has been acting very weird, breathing rapidly, walking low, hiding and not being her normal self. The vet told me that as long as she is not drooling everything is ok. We should take them for two other shots but i'm afraid my cat is having bad reactions to this meds.

Dr. Callum Turner, DVM
Dr. Callum Turner, DVM
3316 Recommendations
All medications carry some side effects which vary from animal (or human) to animal (or human); if Tanny is otherwise alright and isn’t struggling to breathe or in any distress you should monitor her for the time being. However when it comes to future use of antibiotics, this would be down to your Veterinarian’s discretion as they may recommend a different class of antibiotics or a different treatment. Regards Dr Callum Turner DVM

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Char
Russian White
9 Years
Moderate condition
0 found helpful
Moderate condition

Has Symptoms

Scratching above eyes
Excessive licking
Biting at paws, over grooming

Medication Used

Clavamox antibiotic- oral

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.

Dr. Callum Turner, DVM
Dr. Callum Turner, DVM
3316 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

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Oliver
Domestic MH
12 Weeks
Serious condition
0 found helpful
Serious condition

Has Symptoms

Runny Nose
Sneezing

Medication Used

terramycin

Hi! My cat Oliver is 12 weeks. Recently he had one eye that was completely closed shut, and very watery. Along with this he was also sneezing a lot. We went to the vet and were given a eye salve called Terramycin. We put it in one eye the first day but that evening the other eye had the same symptoms. We ending up putting it in both eyes and his eyes seemed to fully open again. This morning he looked much better and was very playful. But in the afternoon, we continued the salve but he seeming very lethargic. He was sneezing a lot, and had runny water mucus, and very red and watery eyes. Would you have any suggestions on what to do next?
Thank you so much,
Kim

Dr. Callum Turner, DVM
Dr. Callum Turner, DVM
3316 Recommendations
It is possible that Oliver may require a more systemic treatment than just the topical eye drops, you should return to your Veterinarian for another examination to determine if systemic antibiotics or another treatment is required; sometimes an infection cannot be treated with topical treatment alone but it is best to start with topical treatment especially in a kitten this age. Regards Dr Callum Turner DVM

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Fiesty
short hair
2 Days
Serious condition
0 found helpful
Serious condition

Has Symptoms

Inflamation
Ears
Swelling
Redness

My cat is about 2 years old and just had 3 teeth pulled 8 days ago due to her stomatitis. She has been on cephalexin for 7 days now, 250mg/5ml 1ml twice daily. (She had been on keflex once before same strength 2ml twice daily.) I just finished her evening dose and noticed her skin is pink and inflamed around her mouth, and pink inside her ears, next to her eyes, and her toes are swollen and pink. I can also see scratching her ear from where she’s been itching. So I believe she’s having an allergic reaction to something,... we recently put her on a renal diet a few weeks ago after her sdma (think thats right) test came back elevated at 17 instead of 14 that our vet said was the high normal. I did give her baby food last night as I had read that it was safe for cats with renal issues and would encourage her to eat. She’s playing, purring, and drinking atm. I thought about giving her Benadryl but I don’t want to hurt her kidneys. It’s Friday night and our vet won’t be open till Monday morning, is there anything I can do for her now should I just watch her or should I look rush her to an emergency that is hours away? She was in the house with the windows open all day. I looked around but I don’t see anything she could’ve gotten into though she does to drink right out of the sink, tub, and if open toilets. Did get her normal plastic bowls a few days ago, but she’s always had plastic bowls.

Dr. Michele King, DVM
Dr. Michele King, DVM
1606 Recommendations
It does sound like Fiesty may be reacting to something, from your description, and it may be the medication, or something in the environment. Without seeing her, I can't recommend giving any medication, unfortunately, but if she is eating, drinking, and purring and seems comfortable, you may be okay to monitor the areas that are pink, as they may get better. If she seems to be getting more pink, your veterinarian may have an after hours number that you can call to see what you can do, as they have seen her. Benadryl can sometimes cause a hyperactive response in cats - there may be better medications for her.

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Lila
Siamese
5 Years
Moderate condition
0 found helpful
Moderate condition

Has Symptoms

irriated eyes
Redness in eyes
Swollen 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?

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Mia
Grey
5 Months
Moderate condition
0 found helpful
Moderate condition

Has Symptoms

Running Nose

Medication Used

Doxycycline

We have four cats. Took two to the vet to get spayed. The cats came back sneezing and blowing their noses. Contacted the vet and they provided Doxycycline. The two cats seem to be better. The other cats started with the same symptoms, gave them Doxycycline. The baby cat has become severely sick. Very lethargic, running eyes and just overall not doing well. Seems like she could allergic to the medicine, I don't know. Going to call the vet in the morning but I hate to go back to the same office. Do you have any advice?

Dr. Callum Turner, DVM
Dr. Callum Turner, DVM
3316 Recommendations
It is possible that your two cats picked up something whilst at the clinic or during transport to or from the clinic and passed it on to your other two cats; antibiotics would be indicated but if your youngest seems to be having a reaction you should stop treating him and get a different antibiotic from your Veterinarian (a phone call may be sufficient depending on the severity and their judgement). Regards Dr Callum Turner DVM

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Jasper
Orange tabby
3 Days
Mild condition
0 found helpful
Mild condition

Has Symptoms

Licking at paws
Chewing paw pads
Itching

Our cat has a bit of an eye infection. She was given a shot and an ointment for her eyes. Thing have been going fine, but she's suddenly been licking and chewing on her paws a lot and licking herself insessenly. Could she be allergic to the ointment?

Dr. Callum Turner, DVM
Dr. Callum Turner, DVM
3316 Recommendations
Licking of the paws is a common sign of allergies, normally towards food; you should discourage Jasper from licking her paws to prevent any other issues, but ideally you should complete the course of treatment to resolve the eye infection. Another cause may be that Jasper is rubbing her eyes and then licking off the ointment from the paws; if the licking becomes excessive you should visit your Veterinarian to discuss alternative treatment. Regards Dr Callum Turner DVM

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Roux
Ragdoll
15 Years
Serious condition
0 found helpful
Serious condition

Has Symptoms

lethargy, pain, hiding

Medication Used

Clavamox antibiotic- oral

What options are available to treat bacterial bladder infection if cat is allergic to antibiotics?
My 15 years old female ragdoll cat was diagnosed last week with bacterial bladder infection. No crystals present. Bladder is soft and normal when palpated. She was given liquid Clavamox (1 ml 2x per day). She began vomiting and had diarrhea 2 hours after first dose. She went to stand up, stumbled and collapsed. stopped eating and drinking. Called vet to report. Didn't give her anymore Clavamox until three days later after she regained her appetite. I tried a second dose with the same results. Called vet. Was told to discontinue Clavamox. Vet says she doesn't know what else to do because my cat is sensitive to many medications. She did not offer any other treatment plan other than an ultrasound to rule out stones. I am trying D-mannose powder in her food and water and slippery elm syrup in her food for inflammation. Blood is gone from her urine. No more straining to pee. She stopped vomiting and is eating again, but she continues to just pee wherever she stands which tells me the infection is still there. Blood work shows elevated liver enzymes and high calcium. Thyroid is perfect. Any suggestions to keep her out of pain and clear up the bacterial infection?

Dr. Michele King, DVM
Dr. Michele King, DVM
1606 Recommendations
Thank you for your email. There are many antibiotics that are available that are not related to Clavamox that might be used to treat her UTI. Cephalosporins and enrofloxacin type medications are two antibiotics that can be quite effective for bladder infections, and tend to cause fewer side effects. It would be best to ask your veterinarian which antibiotics might be helpful if she is sensitive to Amoxi-type drugs.

Thank you Dr. King for your response. I have made an appointment with a new veterinarian to have Roux evaluated. Last night she started sneezing and has now developed a bad head cold/upper respiratory infection. On a good note, she is still eating and drinking water since discontinuing the clavamox. Crossing my fingers this new vet will be able to help her. Thank you again.

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Winston
DOMESTIC
3 Years
Moderate condition
1 found helpful
Moderate condition

Has Symptoms

Hiding

Medication Used

Clavamox antibiotic- oral

My cat has been hiding and in general a lot less active than normal. We have already been to the vet once where the took x-rays, did urin analysts, and blood work. The only thing they could find was that he might have an infection coming because he has some immature white blood cells but other blood levels were normal. He was sent home with some antibiotics that I have been giving him. So that was Sunday, it’s now Wednesday he is eating more, drinking more but still hiding. He uses the litter box maybe three times a day. He’s feces are now runny, something that wasn’t happening before we went to the vet. The vet did tell me that if he wasn’t getting better than I should take him back in to get more test done. I think that he has improved since taking him to the vet but not very much. Is it just something that will take time or should I take him for additional tests?

Dr. Michele King, DVM
Dr. Michele King, DVM
1606 Recommendations
Thank you for your email. Clavamox is a good broad spectrum antibiotic that should help with general infections from abscesses or intestinal infections. Clavamox can cause runny stool, so that may be related. Since I can't examine him, and don't know what blood work was run, if you feel that he isn't getting better, it would be worth a phone call to your veterinarian and ask what sort of time frame they would expect for him to improve, as it has been 3 days. If they feel that he is improving and needs a little more time, you can do that, but if they are surprised that he isn't back to normal, it would be a good idea to take him back for a recheck. I hope that he does well.

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Mico
Persian Cat
4 Years
Moderate condition
0 found helpful
Moderate condition

Has Symptoms

Foaming At The Mouth

I think my cat have flu. Bcs she keep sneezing and have runny nose all the time. So, i gave her the flu med given by vet. But, i was so shocked when a lot of foam/bubble coming out from her mouth. A lot of them. But it okay after a while like after half and hour. What to do? Is it some kind of allergic reaction?

Dr. Callum Turner, DVM
Dr. Callum Turner, DVM
3316 Recommendations
There are a few different products which your Veterinarian may have given to you, without knowing which one I cannot go into specifics; however cats may foam at the mouth due to increased salivation, increased respiration, upset stomach among other causes. If Mico is alright for the time being, I would monitor for any changes and return to your Veterinarian if there is another episode. Regards Dr Callum Turner DVM

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Kali (and) Dozer
Calico
10 Years
Fair condition
0 found helpful
Fair condition

I really just wanted to say what a wonderful thing you do for people and their pets! For Free ...! Do you realize that you are one of the few who truly care about others well fare. You have a very kind and good heart, thank you so much for sharing it with us .

Dr. Callum Turner, DVM
Dr. Callum Turner, DVM
3316 Recommendations
Thank you for your support, we hope that you don’t need to use our service for Kali and Dozer but you know where we are if you need any advice. Regards Dr Callum Turner DVM

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Sofi
DOMESTIC
7 Weeks
Mild condition
0 found helpful
Mild condition

Has Symptoms

Weakness
Foaming At The Mouth
Lethargy

My kitten threw up after taking trimethoprim-sulfamethoxazole. She's 7-8 weeks old. She also poop after throwng up. Before giving her a medicine I feed her fish meat and rice. She's also thin and always sleeping so I took her to bet and they prescribe me the trimethoprim-sulfamethoxazole (anti biotic) 0.1ml

Dr. Michele King, DVM
Dr. Michele King, DVM
1606 Recommendations
Without seeing Sofi, I can't say for sure, but she may have reacted badly to the antibiotic, and she may need a different medication so that she doesn't have GI upset. It would be best to call your veterinarian, let them know what happened, and see if she can get another type of antibiotic if that is what she needs.

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