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Doctor insights on: How Long Does Hives Last From An Allergic Reaction

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How long will hives last if I'm having an allergic reaction to medication?

How long will hives last if I'm having an allergic reaction to medication?

Less than one week: Typically, hives due to a medication will last for only a few days; two weeks tops. Medications that stay in the body for a few days could cause longer reactions. Adverse reactions to medications should always been discussed with and shown to the prescribing physician, so that the true cause is identified, and your chart is marked so you aren't given that medication again in the future. ...Read more

Dr. John Chiu
2,638 Doctors shared insights

Allergies (Definition)

Allergies occur when your immune system is triggered by envirionmental factors it should ignore--for example, pollen in the air, or dander on a cat or dog--and creates cells to fight against them. An allergic reaction typically causes itching, congestion, or drainage, and ...Read more


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How long does it take for hives to show up from allergic reaction to antibiotic?

How long does it take for hives to show up from allergic reaction to antibiotic?

Can vary: Allergic reactions from taking antibiotics can be an immediate event or can take days to develop. When they take a longer period of time, we call them "delayed hypersensitivity reactions". If there is a concern about an allergy to a medication, it is best to speak with the prescribing physician about what to do next. All the best! ...Read more

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How long does it take for an allergic reaction like hives to show up after eating something?

How long does it take for an allergic reaction like hives to show up after eating something?

Not very long: With food allergies hives either alone or as the first symptom of a more serious life-endangering condition called anaphylaxis typically appear within 5 minutes to 2 hours after the first bite. When appearing in a few minutes hives usually appear around the lips, eyes, face & neck. When 1st appearing after 2 hours hives can appear anywhere. Hives may be delayed as long as 8-12 hours after eating. ...Read more

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How long for side effects or allergic reaction of sever hives from zithromax till it clears up? They keep reappearing its been 5 days. My daughter 5y

How long for side effects or allergic reaction of sever hives from zithromax till it clears up? They keep reappearing its been 5 days. My daughter 5y

15 days: The time for 1/2 of azithromycin (zithromax) to be eliminated from the body is approximately 3 days. Drugs generally stay in the body for 5 half lives after the last dose. Azithromycin will stay in her body for about 15 days after the last dose. An allergic reaction can continue until all of the drug is eliminated and for several days thereafter. See md for antihistamine or corticosteroid rx. ...Read more

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I have had a allergic reaction (hives). I'm breakin out on my hands and vagina. (spread there last time) can it be an allergic reaction?

I have had a allergic reaction (hives). I'm breakin out on my hands and vagina. (spread there last time) can it be an allergic reaction?

Visit allergist: A physician should perform a physical exam and review your symptoms history and any medications you might be taking. They can recommend an aggressive antihistamine regimen including h1 and h2 antihistamines and might include a lt rc blocker such as singulair (montelukast). ...Read more

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How long after taking stool softener would it take an allergic reaction, such as hives, to appear?

How long after taking stool softener would it take an allergic reaction, such as hives, to appear?

Depends: Stool softeners are rarely allergens although psyllium allergy has been reported. The onset of allergic reaction can be expected from minutes to 2 hours if you are allergic. However I think the hives are more likely from something else. ...Read more

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What can cause hives besides an allergic reaction?

What can cause hives besides an allergic reaction?

Releasing histamine: Hives are due to a release of histamine in the skin, commonly due to allergy to foods, medicines, viruses, molds, animals, pollens, etc... Some people release histamine and get hives when exposed to cold temperatures, cold water, sunshine, stressful situations, etc... Other people with hives may have internal medical conditions such as chemical imbalances, intestinal parasites, etc... ...Read more

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I just moved into a new house and I'm having an allergic reaction. I have hives all over my body. What should I do?

I just moved into a new house and I'm having an allergic reaction. I have hives all over my body. What should I do?

Take Benadryl (diphenhydramine): Hives can result for exposure to allergens and they can be treated with antihistamines wih or withou steroids. If notice this occurs only in your new home you may be able find the cause. An allergist may be able to help you to find the cause. Once the cause is known then you may be able to get your landlord to help eliminate the cause. For the most part the true cause of hives may not be found. ...Read more

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What are good treatments for hives like allergic reaction?

What are good treatments for hives like allergic reaction?

Antihistamine: An antihistamine such as Diphenhydramine (benadryl) can help with symptoms. Hives can come and go for several days. I usually recommend using a once daily antihistamine such as claritin, zyrtec, or allegra, and using the Benadryl (diphenhydramine) when the hives break through. I will sometimes add h2 blocker such as zantac or pepcid, which also act as antihistamines. ...Read more

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What can cause hives and swelling if its not an allergic reaction?

What can cause hives and swelling if its not an allergic reaction?

Hives and angioedema: Most hives and angioedema are caused by allergic reactions however they can also be caused by reactions to medications or things like heat, cold or sunlight.
A variety of infections, including viral or bacterial infections, or collagen vascular disorders can cause a very similar rash. ...Read more

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Are hives ever just a side effect of a drug, or are they always considered an allergic reaction?

Are hives ever just a side effect of a drug, or are they always considered an allergic reaction?

Not always: Hives may be caused by many things including viral infections. Some drugs like opiates trigger certain types of cells to release histamine and thereby causing hives. Only on rare occasions are hives caused by airborne allergens. On the other hand, drug allergy can indeed cause hives. ...Read more

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When I have an allergic reaction why does alcohol make it worse and make me get hives everywhere?

When I have an allergic reaction why does alcohol make it worse and make me get hives everywhere?

Vasodilation: Alcohol has drug effect making more blood to be pumped to the skin by dilating blood vessels in the skin (vasodilation). With hives you have leaky blood vessels in the skin and the more fluid you pump into a leaky pipe the more it leaks. Over heating, exercise, taking a hot shower and eating spicey food will do the same thing. ...Read more

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Can u tell me the difference between urticaria, dermatitis, and hives? Which of them is caused by allergic reaction?

Can u tell me the difference between urticaria, dermatitis, and hives? Which of them is caused by allergic reaction?

Urticaria is hives: Urticaria is derived from a Latin word meaning to burn. It is the same thing as hives. Hives lasting 6 weeks are not usually allergic in origin. Dermatitis means any kind of inflamed skin. Atopic dermatitis AKA eczema may be due to allergy. There are many other causes of dermatitis. ...Read more

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Can a new manufacturer of the same meds I've been on cause hives or an allergic reaction? Only new med I took was Mucinexx DM. Maybe Mucinexx is prob?

Possibly: If you started a new medication, then it is possible for the new med to cause allergic reaction. Stop using the new medication and see if the hives go away. There are some people who have allergic reaction to generic forms of some medication as well. So of you were switched recently to a generic version, go back to the brand name. I would try the first option of stopping Mucinex (guaifenesin) and observing. ...Read more

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Could a allergic reaction from cat fur be the cause of my hives?

Could a allergic reaction from cat fur be the cause of my hives?

Perhaps: Contact urticaria is known to occur but hives from dander in the air is less likely. Finding the cause for this very annoying condition is often very frustrating. Testing guided by a good history and evaluation can help. ...Read more

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Why are doctors recommending Zantac (ranitidine) for an allergic reaction or hives?

Why are doctors recommending Zantac (ranitidine) for an allergic reaction or hives?

Good question: Hives (or urticaria) represent a sensitivity to something dilating the small vessels under the skin, causing a raised pink lesion; if u press on it, it will blanch, let it go it pinks up again. Many causes: foods, chemicals, perfumes, very often stress. Stress can increase acid formation in stomach, Zantac (ranitidine) reduces it. Over 50% of time, one can't find cause. I treat initially c antihistamines. ...Read more

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I have red blotches on my fingers and hives on my forearm could it be a allergic reaction or something else?

I have red blotches on my fingers and hives on my forearm could it be a allergic reaction or something else?

Hives: Hives are raised, often itchy, red welts on the surface of the skin. They are usually an allergic reaction to food or medicine.
Causes, incidence, and risk factors
when you have an allergic reaction to a substance, your body releases histamine and other chemicals into your bloodstream. This causes itching, swelling, and other symptoms. Hives are a common reaction, especially in people with allergy. ...Read more

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Allergic reaction to insect bite means hives or what else?

Allergic reaction to insect bite means hives or what else?

Allergy to insect bi: Most of the allergies to insect bites caue local reaction and itching. But some people have severe reaction to insect bites and stings especially bee stings. This is a life threatening allergic reaction and is called anaphylaxis, this can cause breathing difficulty and is an emergency. Need to be treated with Epipen (epinephrine) injection and emergency treatment. ...Read more

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I took sulfa for two weeks ending three days ago and I strayed breaking out in hives yesterday. Could this be an allergic reaction?

I took sulfa for two weeks ending three days ago and I strayed breaking out in hives yesterday. Could this be an allergic reaction?

Sulfa allergy: Yes, it is possible to experience an allergic response a few days after completing a course of sulfa. Please notify the prescribing practitioner without delay. Take benadryl (diphenhydramine) 25 mg every 4 hours for four doses. Then see how it is. ...Read more

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Found out my allergic reaction was from tide 2 weeks ago. However; no more steroids. My hives are drying up but still itch. Is this normal?

Found out my allergic reaction was from tide 2 weeks ago. However; no more steroids. My hives are drying up but still itch. Is this normal?

Maybe: Allergic reactions such as hives usually go away completely within two weeks of taking the medication stopping what's causing the allergy. If you're still having itching or any rash after two weeks you really should be seen this could be done with the video consult on telemedicine to determine the next treatment ...Read more

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How can I tell if my child is having an allergic reaction to prelone (prednisolone) syrup or if his hives from before are just getting worse?

How can I tell if my child is having an allergic reaction to prelone (prednisolone) syrup or if his hives from before are just getting worse?

Hives just worse: Prelone (prednisolone) is a med that mimics the stress hormone your body makes to stabilize membranes & stop allergic reactions. It is often give as an oral med to patients who would not like the alternative. A deep intramuscular injection would start working faster to slow the reaction. The oral takes some time to kick in so its common for a reaction to get a bit worse before improving. ...Read more

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When I was a child I accidentally drank overdosed on penicillan and had severe diarhhea. Then I developed hives. Is this an allergic reaction?

When I was a child I accidentally drank overdosed on penicillan and had severe diarhhea. Then I developed hives. Is this an allergic reaction?

Possible not likely: Medication allergy is usually an immediate IgE mediated immune response. In this case the hives would have been expected to come out first. Your hives were probably a stress related reaction to the diarrhea and the overdose amount of penicillin. An allergy specialist can do tests to check specifically for penicillin allergy and if negative, you will have access to an important, cheap class of med ...Read more

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What is the best antihistimane to take for an allergic reaction resulting in hives and or a rash?

What is the best antihistimane to take for an allergic reaction resulting in hives and or a rash?

Any OTC: Antihistamines are good. Benadryl, (diphenhydramine) taken every 6 hours may cause drowsiness, so do not drive. You can use loratadine, zyrtec or Allegra. If severe enough, may need steroids. Best to be evaluated by an allergist. May need to carry epi-pen if severe. ...Read more

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Hives around mouth is there some type of allergic reaction?

Sounds like: You have contact allergy to something you ate, or something else you placed around your mouth, such as cosmetics, toothpaste, mouthwash. If it persists for longer than one day, go see a doctor. If you have breathing problems along with it, right away to the doctor. ...Read more

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My 2 1/2 year has an allergic reaction to keflex has hives all over body how much Benedryl can I give her she is 28 lbs?

My 2 1/2 year has an allergic reaction to keflex has hives all over body how much Benedryl can I give her she is 28 lbs?

Benadryl (diphenhydramine) dosing: Benadryl (diphenhydramine) is effective between 0.5 to 1.0 mg/kg per dose every 8-12 hrs. Based on pt being 28 lbs then a tspn of benadryl (diphenhydramine) 12.5mg/5ml will give pt 12.5 mg which is about 1 mg/kg. ...Read more

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I was given Keflex around 3 months ago for Hidradenitis. I had an allergic reaction and stopped taking it. I've had hives ever since. Why is that?

I was given Keflex around 3 months ago for Hidradenitis. I had an allergic reaction and stopped taking it. I've had hives ever since. Why is that?

Not Keflex: HIves is a particular kind of rash, and rarely lasts more than a few days. And any rash due to cephalexin (Keflex) allergy would not last more than 1-2 weeks after stopping the drug. So whatever the cause of your current rash, it probably isn't hives and cephalexin isn't the cause. If you're taking any other medications, you might be allergic to one of them. Discuss with your doctor. ...Read more

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I've had a allergic reaction. There were hives everywhere. I've been taking meds and recently the hives turned into dark marks that look like scars.

I've had a allergic reaction. There were hives everywhere. I've been taking meds and recently the hives turned into dark marks that look like scars.

See a dermatologist: Cause of hives? Not always allergy. If it was allergy, then allergy to what? Benadryl is a brand name for diphenhydramine which is useful mainly as a sleeping pill. There are much better antihistamines which will be less likely to make you sleepy. Do not drive after taking Benadryl. If a rash, not hives, no antihistamine will help. Start with a precise diagnosis if possible. ...Read more

Dr. Daniel Saurborn
3 Doctors shared insights

Hives (Definition)

An outbreak of red bumps or wheals that appear quickly after exposure to certain allergens (foods, medications, other substances). They can vary in size, are itchy, can burn, and can last for up to ...Read more


Dr. John Chiu
1,044 Doctors shared insights

Allergic Reaction (Definition)

Sensitivities to substances, called allergens, that come into contact with the skin, nose, eyes, respiratory tract, and gastrointestinal tract. They can be inhaled into the ...Read more