Allergies to sulfa drugs what to avoid

The symptoms and severity of a sulfa allergy can vary but generally involve the appearance of a widespread rash. Occasionally a photosensitive rash may develop, meaning that a rash will happen in areas exposed to sunlight or other UV light while on the medication.

Other serious manifestations of a sulfa allergy include:

Sulfonamide antibiotics

Adverse reactions to sulfonamide antibiotics are estimated to happen in 3-6% of treatment courses. The majority of these reactions are not of an allergic nature. Types of non-allergic reactions to sulfonamide antibiotics include nausea and diarrhoea, candidiasis, folate deficiency, and headaches.


In the majority of cases, a person with a sulfa allergy will own experienced an allergic reaction to one or more of the following antibiotic drugs:

  1. Bactrim (sulfamethoxazole and trimethoprim)
  2. Septra (sulfamethoxazole and trimethoprim)
  3. Pediazole (erythromycin and sulfafurazole)

These reactions are not every that unusual and affect around 3 percent of every people. This is a rate similar to what is seen with other types of antibiotics, including penicillin.

Certain people appear to be at higher risk of sulfa allergy than others.

These include those who, for various reasons, own a suppressed immune system (such as organ transplant recipients and people with HIV/AIDS).

Medications to Avoid

People with a known sulfa allergy should always check with their doctor before starting a new medication.

Allergies to sulfa drugs what to avoid

This is especially true for those who own had a previous severe reaction.

In addition to oral antibiotics, topical sulfonamides should be avoided. These include:

  1. Silver sulfadiazine ointments used to treat burns
  2. Sulfacetamide eye drops, shampoos, or creams
  3. Sulfanilamide vaginal preparations

Similarly, the oral drug Azulfidine (sulfasalazine), used to treat inflammatory bowel disease and rheumatoid arthritis, should be avoided.

Keep in mind that the risk of cross-reactivity to non-antibiotic sulfonamides is low.

Allergies to sulfa drugs what to avoid

This means that it's generally safe to take the following drugs:

  1. Oral sulfonylureas-class drugs used to treat diabetes
  2. Diuretics (water pills) such as HCTZ (hydrochlorothiazide) and Lasix (furosemide)
  3. Celebrex (celecoxib), a COX-2 inhibitor used to treat arthritis and pain


The first-line of treatment of a sulfa allergy is typically the termination of the suspected drug.

Anaphylaxis requires immediate epinephrine use and medical care.

Stevens-Johnson syndrome or toxic epidermal necrolysis are also potentially life-threatening conditions that require immediate medical evaluation; in severe cases, management in a burn unit may be required.

In milder cases where a sulfa drug is considered essential to the treatment of an infection, an allergist or other qualified physician may supervise the istration of smaller doses and gradually increase them as the drug is better tolerated.


There's no validated skin or blood test available to diagnose a sulfa allergy.

The diagnosis is generally made on careful review of the suspected reaction and history of current and previous medication use.

Sulfite and Sulfate Allergies

People will often error a sulfa allergy for a sulfite allergy. Sulfites are preservatives found in foods and medications. These include:

  1. Sodium metabisulfite
  2. Sodium sulfite
  3. Potassium bisulfite
  4. Sodium bisulfite
  5. Potassium metabisulfite

Sulfates are drugs containing sulfuric acid. As with sulfites, sulfates may cause allergy, but the drugs are in no way related to sulfonamides or sulfa-allergy risk.

These include medications such as:

  1. Iron sulfate used to treat iron-deficiency anemia
  2. Albuterol sulfate used to treat bronchial spasms
  3. Chondroitin sulfate used to treat osteoarthritis
  4. Codeine sulfate, an opioid drug used for pain relief


Sulfa, sulfite, sulfate, and sulfur are four terms that sound similar but own extremely diverse allergy profiles. As healthcare practitioners, it is significant to understand these four terms to establish whether patients own true allergy, cross-allergy, or no allergy among drugs, herbs and foods.

1. Sulfa (sulfonamide antimicrobials and sulfonamide non-antimicrobials)

“Sulfa drugs” refers primarily to sulfonamide antimicrobials, such as sulfamethoxazole, sulfisoxazole, sulfafurazole, and sulfadiazine, containing sulfur, oxygen, nitrogen and other groups.

Allergic reactions happen due to the actions of sulfonamide antimicrobials, not the actual sulfur. Though 3 to 4% of patients claim to allergic to sulfa drugs, only 3% of these patients own a true allergy to sulfonamide antimicrobials.[1],[2],[3] True hypersensitivity reactions, such as rash and hives, will generally resolve within two weeks after discontinuation of the drug. Severe hypersensitivity reactions, such blistering and mucosal reactions, may require hospitalization.[4],[5],[6]

Sulfonamide non-antimicrobials include drugs such as furosemide, hydrochlorothiazide, acetazolamide, sulfonylureas, and celecoxib.

Sulfonamide antimicrobials and sulfonamide non-antimicrobials own diverse chemical structures, and there is no clinical evidence of cross-allergy.[7],[8]

Sulfonamides were originally derived from red dye. There is no data available to determine whether there is cross-allergy with Chinese herbs that own been used as blue/green dye, such as BanLanGen (Radix isatidis), DaQingYe (Folium isatidis) and QingDai (Indigo naturalis).

Table 1.

Sulfonamide Antimicrobials

Sulfamethoxazole-trimethoprim (Septra, Bactrim)
Sulfisoxazole-erythromycin (Pediazole)
Table 2.

Allergies to sulfa drugs what to avoid

Sulfonamide Non-Antimicrobials

Celecoxib (Celebrex)
Furosemide (Lasix)
Glimepiride (Amaryl)
Glyburide (Glynase, Diabeta)
Hydrochlorothiazide (Microzide)
Sumatriptan (Imitrex)

What if I forget to take it?

If you forget to take a dose, take it as soon as you remember, unless it’s almost time for your next dose.

In this case, just leave out the missed dose and take your next dose as normal.

Never take 2 doses at the same time. Never take an additional dose to make up for a forgotten one.

If you often forget doses, it may assist to set an alarm to remind you.

You could also enquire your pharmacist for other ways to remember your medicine.


Sulfa, sulfite, sulfate, and sulfur are four terms that sound similar but own completely diverse clinical implications. In addition to inquiring after patients’ allergy profiles, healthcare practitioners must assist patients understand the differences between these four terms so patients who own true allergy or cross-allergy with sulfa, sulfites, and/or sulfates can avoid those drugs, herbs, foods, and products.

  1. Sulfites, including bisulfite, metabisulfite, and sulfur dioxide, are widely present in foods, dietary supplements, drugs and cosmetic products.

    There is no evidence of cross-allergy between sulfonamide antimicrobials and sulfites. For patients with true sulfite allergy, seven herbs (listed above) should be tested to ensure they are sulfite-free.

  2. Sulfa drugs, specifically sulfonamide antimicrobials, may cause allergy in approximately 3% of the population. There is no clinical evidence of cross-allergy between sulfonamide antimicrobials and sulfonamide non-antimicrobials, or documented evidence of cross-allergy between sulfonamide antimicrobials and Chinese herbs.
  3. Sulfates are widely present in everyday life as drugs, dietary supplements, and personal care products.

    Sulfate allergies are rare. There is no evidence of cross-allergy between sulfates with sulfonamide antimicrobials and sulfites.

  4. Sulfur is a chemical element that is naturally present in human body and numerous foods.

    Allergies to sulfa drugs what to avoid

    It is virtually impossible to be allergic to sulfur.


Sulfates contain one sulfur atom surrounded by 4 oxygen atoms. Sulfates are widely present in everyday life: sulfate-containing drugs (i.e., ferrous sulfate), dietary supplements (i.e., glucosamine sulfate), and personal care products (i.e., shampoo, toothpaste, shaving foam, body washes and facial cleansers).[13]

Sulfate allergies are rare. In addition, sulfates, again, are diverse from sulfonamide antimicrobials as well as sulfites and do not cause allergic or sensitivity reactions.


Sulfites are molecules that contain one sulfur atom surrounded by 2 or 3 oxygen atoms.

Sulfites occur naturally in some foods during the fermentation process, such as red wine. Sulfites, which can be added as preservatives to prevent food from turning color and bacteria from spoiling foods, are commonly found in foods such as dried fruits (excluding dark raisins and prunes), bottled lemon juice (non-frozen), bottled lime juice (non-frozen), sauerkraut (and its juice), grape juices (white, white sparkling, pink sparkling, red sparkling), salad, and pickled cocktail onions.

Sulfites are also present in numerous oral medications (adrenaline, isoprenaline, isoproterenol, isoetharine, phenylephrine, dexamethasone and injectable corticosteroids, dopamine, local anaesthetics, propofol, aminoglycoside antibiotics, metoclopramide and doxycycline) and topical creams and ointments (antifungals and corticosteroids).

Lastly, numerous cosmetic products also contain sulfites (hair colors and bleaches, home permanent solutions, skin fading/lighteners, untrue tan lotions, anti-aging creams and moisturizers, facial cleansers, around-the-eye creams, body washes/cleansers, hair sprays, perfumes, blush, bronzers, and highlighters).[9]

Sulfites are present in numerous forms including bisulfite, metabisulfite, and sulfur dioxide. Sulfites cause allergy in approximately 1% of population. Hypersensitivity reactions include hives, dyspnea, and in severe cases, anaphylactic shock. Products that contain more than 10 ppm of sulfite require disclosure on the label, according to the US FDA.[10]

Sulfites and sulfonamides own diverse chemical structures, and there is no evidence of cross-allergy between sulfites and sulfonamides.[11],[12]

For patients with sulfite allergy, inquiry should be made to ensure the seven herbs listed under are sulfite free.

Chinese herbs that may be treated with sulfite include: BaiGuo (Semen Ginkgo), BaiHe (Bulbus Lilii), GeGen (Radix Puerariae Lobatae), GouQiZi (Fructus Lycii), RenShen (Radix et Rhizoma Ginseng), ShanYao (Rhizoma Dioscoreae), YuZhu (Rhizoma Polygonati Odorati).

Table 3. Foods That Contains Sulfites
Fruits, dried (excluding dark raisins and prunes)
Grape juices (white, white sparkling, pink sparkling, red sparkling)
Lemon juice, bottled (non-frozen)
Lime juice, bottled (non-frozen)
Pickled cocktail onions
Sauerkraut (and its juice)
Table 4.

Drugs That Contains Sulfites

Aminoglycoside antibiotics
Anaesthetics, local
Antifungal (creams and ointments)
Corticosteroids (creams and ointments)
Corticosteroids (injectable)
Table 5.

Cosmetic ProductsThat Contains Sulfites

Anti-aging creams and moisturizers
Around-the-eye creams
Body washes/cleansers
Bronzers and highlighters
Facial cleansers
False tan lotions
Hair colors and bleaches
Hair sprays
Home permanent solutions
Skin fading/lighteners
Table 6. Herbs That May Contain Sulfites
BaiGuo (Semen Ginkgo)
BaiHe (Bulbus Lilii)
GeGen (Radix Puerariae Lobatae)
GouQiZi (Fructus Lycii)
RenShen (Radix et Rhizoma Ginseng)
ShanYao (Rhizoma Dioscoreae)
YuZhu (Rhizoma Polygonati Odorati)


Sulfur is a chemical element that is naturally present in numerous amino acids and other significant molecules in the body.

In fact, after calcium and phosphorus, it is the third most abundant mineral in the human body. Sulfur is also found in numerous foods, such as garlic, onions, and broccoli.[14]

While some individuals may be allergic to the action of sulfonamide antimicrobials and sulfites, they do not have true allergy to sulfur itself. True allergy to sulfur is virtually impossible, as sulfur is present in every living tissues and humans cannot survive without it.

How to take it

Clarithromycin tablets come in 250mg or 500mg strengths.

Swallow clarithromycin tablets or capsules whole with a drink of water, with or without food.

Do not chew or break them.

Clarithromycin granules come in 250mg sachets. Open the pack — or packets — and stir the granules with a little quantity of water to drink.

There’s also a liquid clarithromycin for children and people who discover it hard to swallow tablets.

If you or your kid are taking clarithromycin as a liquid, your pharmacist will generally make it up for you.

The medicine will come with a plastic syringe or spoon to assist you take the correct quantity.

If you don’t own a syringe or spoon, enquire your pharmacist for one.

Do not use a kitchen teaspoon as it will not give the correct amount.

A Expression From Verywell

The nuances of a sulfa allergy can be tricky to tease out, even for some healthcare providers.

That's why it's significant to tell your doctor about any prior reaction you may own had to a sulfa medication (or any other drug for that matter). Sharing that information will make it easier for your doctor to prescribe a substitute that's less likely to cause an allergy.

It's significant to take every drug-related rash seriously, no matter how mild it may be. In some cases, continuing a sulfa-drug while having mild symptoms may cause those mild symptoms to become severe and life-threatening.

While sulfites can cause an ​allergy, there is no direct relationship between a sulfa and sulfite allergy—so someone with a sulfa allergy doesn't own to avoid sulfites (or vice versa).

The usual dose of clarithromycin is 250mg to 500mg twice a day.

The dose may be lower for children and if you own kidney problems.

If your doctor prescribes slow release or modified release tablets, the dose is 500mg once a day.

These tablets release the medicine slowly, which means that 1 dose a day is enough.

Try to take your medicine at the same time every day.

What if I take too much?

Taking an additional dose of clarithromycin by accident is unlikely to harm you or your kid.

It may give you temporary side effects, love stomach pain, feeling and being ill, and diarrhoea.

Talk to your pharmacist or doctor if you’re worried or get severe side effects, or if you or your kid accidentally take more than 1 additional dose.

Written by: John K.

Chen, PhD, PharmD, OMD, LAc

Reviewed by Tina T. Chen, LAc; Donna Chow Sanchez, LAc; and Anita Chen Marshall, DAOM, PharmD, PhD, LAc

About the Author

Dr. John K. Chen, PhD, PharmD, OMD, LAc, is the lead author of Chinese Medical Herbology and Pharmacology (2003, Art of Medicine Press) and Chinese Herbal Formulas and Applications (2008, Art of Medicine Press).

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Multiple drug intolerance syndrome: prevalence, clinical characteristics, and management. Ann Allergy Asthma Immunol. 2012;108:88-93.

[2] Strom BL, Schinnar R, Apter AJ, Margolis DJ, Lautenbach E, Hennessy S, et al. Absence of cross-reactivity between sulfonamide antibiotics and sulfonamide nonantibiotics. N Engl J Med. 2003;349:1628–1635.

[3] Slatore CG, Tilles SA. Sulfonamide hypersensitivity. Immunol Allergy Clin N Am. 2004;24:477–490.

[4] Joint Task Force on Practice Parameters, the American Academy of Allergy, Asthma and Immunology, the American College of Allergy, Asthma and Immunology, and the Joint Council of Allergy, Asthma and Immunology.

Drug allergy: an updated practice parameter. Ann Allergy Asthma Immunol. 2010;105:259-273.

[5] Zawodniak A, Lochmatter P, Beeler A, Pichler WJ. Cross-reactivity in drug hypersensitivity reactions to sulfasalazine and sulfamethoxazole.

Allergies to sulfa drugs what to avoid

Int Arch Allergy Immunol. 2010;153:152-156.

[6] Slatore CG, Tilles SA. Sulfonamide hypersensitivity. Immunol Allergy Clin North Am. 2004;24:477-490.

[7] Hemstreet BA, Sheet RL 2nd. Sulfonamide allergies and outcomes related to use of potentially cross-reactive drugs in hospitalized patients. Pharmacotherapy. 2006;26:551-557.

[8] Vally H, Misso NL. Adverse reactions to the sulphite additives. Gastroenterol Hepatol Bed Bench. 2012;5:16-23.

[9] Sampson HA, Aceves S, Bock SA, et al. Food allergy: a practice parameter update–2014. J Allergy Clin Immunol. 2014;134:1016-1025.

[10] Wolke, RL.

Sulfa-Sulfites Confusion. The Washington Post. October 26, 2005.

[11] Brackett CC, Singh H, Block JH. Likelihood and mechanisms of cross-allergenicity between sulfonamide antibiotics and other drugs containing a sulfonamide functional group. Pharmacotherapy. 2004;24:856-870.

[12] Hemstreet BA, Sheet RL 2nd. Sulfonamide allergies and outcomes related to use of potentially cross-reactive drugs in hospitalized patients. Pharmacotherapy. 2006;26:551-557.

[13] Dibbern DA Jr, Montanaro A.

Allergies to sulfonamide antibiotics and sulfur-containing drugs. Ann Allergy Asthma Immunol. 2008;100:91-100.

[14] Dibbern DA Jr, Montanaro A.

Allergies to sulfa drugs what to avoid

Allergies to sulfonamide antibiotics and sulfur-containing drugs. Ann Allergy Asthma Immunol. 2008;100:91-100.


Sulfa drugs (also called sulphur drugs or sulfonamide-containing drugs) is an imprecise term that generally refers to drugs that contain a sulfonamide functional group in their chemical structure. These drugs own a variety of uses and can be classified into antibiotics and non-antibiotic drugs. Sulfonamide-containing drugs are frequently implicated in allergic and non-allergic reactions.


Allergies to sulfa drugs what to avoid