Everything you need to know about the sulfa allergy. What it is, symptoms, treatment, what foods to avoid, + more to stay safe.
The sulfa allergy is one of the major 8 allergies of the world with around 3% of people having a sulfa allergy. People who have asthma are at particular risk for developing a severe allergic reaction to sulfa.
Sulfa and sulfites have been used for centuries as a food preservative in the form of sulfur salts. They also occur naturally in the environment and even within our own bodies. Sulfa is a part of some medications, including those for skin disorders, eye infections, and rheumatoid arthritis.
There are 4 main types of sulfa that cause sensitivities and true allergic reactions. Some of them are mild but sulfa allergies can be very severe.
This article walks you through all aspects of a sulfa allergy, including all 4 types of sulfa, symptoms, what to avoid, what you can still enjoy, and how best to manage your sulfa allergy.
- What is a sulfa allergy?
- What is sulfa?
- Sulfa Medication Allergy Symptoms
- Sulfite Allergy Symptoms
- Sulfate Allergy Symptoms
- Anaphylactic reaction
- How to manage sulfa allergies
- What foods contain sulfa?
- Medications that contain Sulfonamide Antimicrobials
- Medications that contain Sulfa Non-Antimicrobials
- Medications that contain Sulfa + Sulfites
- Other products that contain Sulfites
- Products that contain Sulfates
- Herbs that May Contain Sulfites
- Cross reactions with sulfa allergies
What is a sulfa allergy?
A sulfa allergy is a response of the body's own immune system thinking that sulfa is a threat. This triggers an autoimmune response known as an allergic reaction.
People who have asthma are generally considered at higher risk for a sulfa allergy or sulfite sensitivity.
Additionally, people who are living with HIV or AIDS may be more likely to have a sulfa allergy.
There are some people who do not have a true allergy, but rather, hypersensitivity reactions. These should be treated with the same care as those with a sulfa allergy.
What is sulfa?
The 4 kinds of sulfa are:
- Sulfa (sulfonamide antimicrobials and sulfonamide non-antimicrobials)
A person can be allergic to just one or all 4 types of sulfa.
Sulfa/sulfate allergies are most common in asthmatics. If you do have asthma, your chance of being sensitive to sulfites ranges between 1 in 40 to 1 in 100.
If you suspect that you are allergic, you should make an appointment with your doctor to confirm.
Sulfa allergies have no cure and you will need to avoid sulfa in all its forms for your entire life.
Make sure you speak with your doctor to know what your allergy and asthma action plan is in case of exposure.
The FDA now requires sulfites to be declared on the label of any food containing more than 10 parts per million (ppm). Other products like body care items are not required to be labeled.
A “sulfa drug” usually refers to the first kind of sulfa, sulfonamide antimicrobials. The allergic reaction occurs due to the actions of the sulfonamide antimicrobials and not the actual sulfur.
There are people who are hypersensitive to sulfa drugs and have a reaction such as a rash or hives, that will resolve itself when the drug causing this reaction is stopped.
A true sulfa allergy is usually quite severe and causes blistering of the mucosal systems and oftentimes required hospitalization.
Sulfites are molecules that contain one sulfur atom and 2 or 3 oxygen atoms. They are naturally occurring in foods during the fermentation process, as in red wine.
These sulfites are added to foods and medications as a preservative both to keep food from turning colors and from bacteria from spoiling the food.
Sulfites cause an allergy in about 1% of the population and any foods or products that contain more than 10 ppm of sulfites must be labeled as such according to the United States FDA.
For people with sulfite allergies, you may or may not be allergic to the other types of sulfa. Sulfites and sulfonamides have different chemical structures and there is no evidence of a cross-allergy between them at this time.
Sulfates contain one sulfur atom surrounded by 4 oxygen atoms. Sulfates are used in many products in our lives including medications, supplements, and bath care products.
Many asthmatics have a sulfate allergy or sensitivity. It is estimated that up to 10% of all asthmatics have a reaction to sulfates.
Sulfur is a basic chemical element that is present in our world naturally. It is the third most abundant mineral in the human body! It is naturally found in foods such as cabbages and onions.
A true allergy to sulfur has not been documented at this time. Most people who are allergic to sulfur are allergic to the action of the sulfonamide antimicrobials and sulfites, not the sulfur itself. Again, sulfur is present in the human body naturally. However, it is possible to be sensitive and allergic to anything.
Sulfa Medication Allergy Symptoms
If you are allergic to any sulfa form, you may have one or more of these reactions:
- Sulfonamide drug hypersensitivity syndrome
- Rash, fever, and organ problems that begin a week after starting the medication
- Drug eruption
- Red, swollen, rounded patches on the skin that form 30 minutes to 8 hours after starting the medication
- Stevens-Johnson syndrome
- A life-threatening reaction that causes the skin to blister and peel off.
Other reactions to sulfa drugs include:
- Trouble sleeping
- Cloudy urine (crystalluria)
- Low blood counts
Sulfite Allergy Symptoms
Sulfite allergies cause different adverse reactions than the sulfa drug allergies. Common symptoms for sulfite allergies include:
- Asthma attacks
- Chest tightness
- Shortness of breath
- Anaphylactic shock
- Allergic rhinitis (hay fever)
- Angioedema (swelling)
- Abdominal pain
Sulfate Allergy Symptoms
Some common reactions to sulfates in things like shampoos and other body care products include:
- Scalp irritations (eczema, dandruff, psoriasis)
- Dry hair
- Breaking and brittle hair
- Split ends
- Skin irritations
- Red, itchy skin
- Irritation to the eyes, skin, lungs
It is rare that sulfa medications will cause an anaphylactic reaction. However, it can still happen.
It is more common for people with sulfite allergies to have asthma reactions and anaphylactic reactions.
If an anaphylactic reaction happens, call 911 or your local emergency number immediately. Signs and symptoms of an anaphylactic reaction include:
- Swelling and tightening of the throat
- Difficulty breathing
- Chest pain or tightness
- Trouble swallowing
- Dizziness or fainting
- Change of the normal coloring of the skin in the mucous membranes (inner lips, gums, around the eyes, and the nail beds)
- Light skin, check for signs of a dark blue tint in the mucous membranes
- Medium skin, check for signs of a gray-green tint in the mucous membranes
- Dark skin, check for signs of a gray or white tint in the mucous membranes
If you have had an anaphylactic reaction in the past, talk with your doctor and/or your healthcare provider about receiving an epinephrine auto-injector (Epi Pen). If you have been given one and are allergic to sulfa drugs, it is important that you still use the Epi Pen. This is a life saving medical device and should not be avoided if it is needed.
A diagnosis can begin by sharing your history and aspects of your asthma with your doctor.
There is currently no reliable blood test or skin allergy test to check for sulfite reactions. A food challenge is the best method of testing if you are allergic. This should be done under the supervision of a doctor who can confirm or exclude if you are allergic.
The challenge is normally done is a small step-up testing. Small does of sulfites are used so that if a reaction occurs, it is mild. After each dose, a waiting time of 20 to 30 minutes happens to allow time for the body to react. Once a reaction takes place it is measured by a lung function test (a spirometry).
If the sulfa allergy is an acute reaction to drugs, the best treatment is to stop the medication.
Following that, your doctor may prescribe different treatment options depending on your unique symptoms.
For example, for hives or other rashes, a doctor may prescribe antihistamines or corticosteroids.
If a person is having asthma symptoms or other respiratory symptoms, they may need a bronchodialator.
How to manage sulfa allergies
The best way to manage your sulfa allergy is to reduce your exposure when possible and to not use products or medications that contain the type of sulfa you are allergic to.
People with asthma in particular should continue to use their asthma medications as directed by their doctors. This is because asthma can cause severe complications for those with a sulfa allergy.
What foods contain sulfa?
Sulfites are commonly found in the following foods:
- Fruits, dried (excluding dark raisins and prunes)
- Grape juices
- Lemon juice (bottled, non-frozen)
- Lime juice (bottled, non-frozen)
- Instant teas
- Dried potatoes, instant mashed potatoes
- Pickled cocktail onions
- Pre packaged salads
- Sauerkraut (and its juice)
- Sulfur powder may be added on top of the crustaceans to stop them from discoloring
- Prepared meats
- Sulfites are added to help preserve the lunch meats
Sulfites often go under hidden names of labels. Avoid the following:
- Sulphur dioxide
- Sodium sulfite
- Sodium bisulfite
- Sodium metabisufite
- Potassium metabisulfite
- Calcium sulphite
- Calcium bisulfite
- Potassium bisulfite
Medications that contain Sulfonamide Antimicrobials
- Sulfa-methoxazole-trimethoprim (Septra, Bactrim)
- Sulfisoxazole-erythromycin (Pediazole)
Medications that contain Sulfa Non-Antimicrobials
- Celeboxib (Celebrex)
- Furosemide (lasiz)
- Glimepride (amaryl)
- Glyburide (Glynase, Diabeta)
- Hydrochlorothiazide (Microzide)
- Sumatriptan (Imitrex)
Medications that contain Sulfa + Sulfites
- Adrenalin chloride 1:1000 concentration
- AK-Dex, Ocu-Dex (dexamethasone)
- Amikin (amikacin)
- Aminoglycoside antibiotics
- Anesthetics, local
- Antifungals (creams and lotions)
- Aramine (metaraminol)
- Bleph-10 (sulfacetamide sodium)
- Bronkosol (isoetharine)
- Celestone (betamethasone phosphate)
- Compazine (prochlorperazine)
- Corticosteroids (creams and ointments)
- Corticosteroids (injectables)
- Decadrom (dexamethasone phosphate)
- Demerol (meperidine)
- Garamycin (gentamycin)
- Isoetharine HCl
- Isuprel (isuprel hydrochloride)
- Levophed (norepinephrine)
- Nebcin (tobramycin)
- Novocaine (procaine)
- Phenegran (promethazine)
- Pred-Forte (prednisolone acetate)
- Pred-Mild (prednisolone)
- Thorazine (chlorpromazine)
- Xylocaine with epinephrine (lidocaine with epinephrine)
Other products that contain Sulfites
- Anti-aging creams and moisturizers
- Around-the-eye creams
- Body washes/cleansers
- Bronzers and highlighters
- Facial cleansers
- False tan lotions
- Hair colors
- Hair bleaches
- Hair sprays
- Home renovating materials
- Skin lighteners
Products that contain Sulfates
- Liquid soaps
- Laundry detergents
- Dish detergents
- Bath bombs
- Skin care products
- Hair care products
Herbs that May Contain Sulfites
- Bai Guo (Semen Ginkgo)
- Bai He (Bulbus Lilii)
- Ge Gen (Radix Puerariae Lobatae)
- Gou Qi Zi (Fructus Lycii)
- Ren Shen (Radix et Rhizoma Ginseng)
- Shan Yao (Rhizoma Dioscoreae)
- Yu Zhu (Rhizoma Polygonati Odorati)
Cross reactions with sulfa allergies
There are lots of foods that can cause a reaction to those who are extremely sensitive to sulfites. These foods contain low to moderate levels of sulfites, usually between 10 and 49.9 ppm of sulfites. If you are very allergic, use caution when eating the following, or avoid altogether:
- Avocado dip. Guacamole
- Cheeses, especially hard cheeses
- Cider vinegar
- Clam chowder
- Corn syrup
- Cornbread, muffin mix
- Dehydrated vegetables
- Fresh mushrooms
- Imported fruit juices and soft drinks
- Imported jams and jellies
- Imported sausages and meats
- Maple syrup
- Pickled peppers
- Pickles, relish
- Potatoes (frozen)
- Shrimp (fresh)
Some people, particularly those with asthma, are allergic to one or multiple forms of sulfa. They are a common additive to medications, foods, and body care products.
The cause of sulfite allergies is unknown, though we have made the connection of it worsening asthma, especially if the asthma is not well controlled.
Thanks to strict labeling of foods, it is easy to spot sulfites in packaged foods. Be aware of restaurant foods, especially potatoes. Always read the labels to avoid sulfates in body care products. And make sure to talk with your doctor about your sulfa allergy so that you never are given medication that contains sulfa.
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