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Medical Disclaimer: This information is for educational purposes only and is not a substitute for professional medical advice.
Non-Standardized Food Allergenic Extract [EPC]
Lettuce extracts are utilized primarily as non-standardized allergenic extracts for diagnostic testing and immunotherapy, belonging to classes such as Non-Standardized Plant Allergenic Extracts and Provitamin D2 Compounds.
Name
Lettuce
Raw Name
LETTUCE
Category
Non-Standardized Food Allergenic Extract [EPC]
Drug Count
4
Variant Count
4
Last Verified
February 17, 2026
About Lettuce
Lettuce extracts are utilized primarily as non-standardized allergenic extracts for diagnostic testing and immunotherapy, belonging to classes such as Non-Standardized Plant Allergenic Extracts and Provitamin D2 Compounds.
Detailed information about Lettuce
This page is for informational purposes only and does not replace medical advice. Consult a qualified healthcare professional before using any medication containing Lettuce.
In clinical practice, Lettuce extracts are utilized by allergists and immunologists to identify specific sensitivities in patients presenting with food allergies, oral allergy syndrome (OAS), or occupational asthma. Because these extracts are 'non-standardized,' their potency is not measured in standardized units (like Bioequivalent Allergy Units or BAU), but rather by weight-to-volume (w/v) ratios or PNU (Protein Nitrogen Units). The FDA has historically permitted the use of these extracts under the Biologics Control Act, provided they meet safety and purity standards, though they are often subject to ongoing review for efficacy in the context of modern immunotherapy.
The therapeutic and diagnostic mechanism of Lettuce extract is rooted in the principles of immunology. When used as a diagnostic agent in skin prick testing (SPT), the extract introduces specific Lettuce-derived proteins—most notably Lipid Transfer Proteins (LTPs) such as Lac s 1—to the patient's skin. If the patient has been sensitized, their mast cells will be coated with Lettuce-specific Immunoglobulin E (IgE) antibodies. Upon contact with the extract, these antibodies cross-link, triggering mast cell degranulation and the release of histamine and other inflammatory mediators. This results in a localized 'wheal and flare' reaction, which the healthcare provider measures to determine the degree of sensitivity.
At a molecular level, Lettuce contains several bioactive compounds that contribute to its classification in other EPCs. As a Provitamin D2 Compound, it contains ergosterol, which can be converted into ergocalciferol. As a Vitamin A [EPC] source, it is rich in beta-carotene, a carotenoid that the human body metabolizes into retinol (Vitamin A). Furthermore, certain wild variants of the Lactuca genus (such as Lactuca virosa) contain lactucarium, a milky fluid containing lactucin and lactucopicrin, which have been studied for their sedative and analgesic properties, though these are not the primary focus of standardized medical extracts.
> Important: Only your healthcare provider can determine if Lettuce extract testing or therapy is right for your specific condition. Diagnostic procedures must always be performed under medical supervision where emergency equipment is available.
For adults, the standard dosage involves the application of a single drop of the 1:10 or 1:20 w/v glycerinated Lettuce extract to the forearm or back. A sterile lancet is then used to prick the skin through the drop. A positive control (histamine) and a negative control (saline/glycerin) must be administered simultaneously for accurate interpretation.
If the SPT is negative but clinical suspicion remains high, a healthcare provider may administer 0.02 mL to 0.05 mL of a 1:100 or 1:1000 v/v dilution via intradermal injection. This is a more sensitive, yet higher-risk, diagnostic procedure.
Pediatric dosing for skin prick testing is generally identical to adult dosing in terms of concentration, though the number of tests performed in a single session may be limited to prevent patient distress. Intradermal testing is rarely performed in young children due to the increased risk of systemic reactions.
No specific dosage adjustments are required for diagnostic testing, as systemic exposure is minimal. However, patients with end-stage renal disease may have altered skin reactivity (uremic pruritus), which can interfere with test interpretation.
No dosage adjustments are necessary for Lettuce allergenic extracts in patients with liver disease.
Elderly patients may exhibit reduced skin turgor and diminished wheal and flare responses. Healthcare providers may need to adjust the interpretation of the test results rather than the dosage itself.
Lettuce allergenic extract is not for self-administration. It must be administered by a trained medical professional (usually an allergist or nurse) in a clinical setting.
Storage: The extract must be stored in a refrigerator between 2°C and 8°C (36°F to 46°F). It should not be frozen. If the extract becomes cloudy or shows precipitation, it should be discarded.
In the context of diagnostic testing, a missed appointment simply requires rescheduling. In the rare event that Lettuce extract is being used for immunotherapy, a missed dose may require a 'step-back' in concentration to avoid a systemic reaction when therapy resumes. Consult your allergist for a specific catch-up schedule.
An 'overdose' in the context of allergenic extracts refers to the administration of a concentration too high for the patient's sensitivity level, leading to a systemic allergic reaction.
> Important: Follow your healthcare provider's dosing instructions. Do not attempt to use clinical-grade allergenic extracts at home.
The most frequent side effects associated with Lettuce allergenic extract are localized to the site of administration. These are generally expected as part of the diagnostic process.
While rare during skin prick testing, serious systemic reactions can occur, particularly during intradermal testing or immunotherapy.
> Warning: Stop the procedure and call for emergency assistance immediately if you experience any of the following:
There are no known long-term systemic side effects from the occasional diagnostic use of Lettuce extract. However, repeated exposure through immunotherapy carries a small, cumulative risk of developing increased sensitivity or 'large local reactions' (LLRs) that can cause significant discomfort.
Lettuce allergenic extracts, like all allergenic extracts, can cause severe life-threatening systemic reactions, including anaphylaxis. Patients with unstable or severe asthma are at increased risk for fatal outcomes. This product must only be administered by healthcare providers prepared to manage anaphylaxis. Patients must be observed for at least 30 minutes after administration. Epinephrine must be immediately available.
Report any unusual symptoms to your healthcare provider. If you experience a delayed reaction after leaving the clinic, use your prescribed epinephrine auto-injector and seek emergency care.
Lettuce allergenic extract is intended for diagnostic or therapeutic use by specialists only. It is not a self-administered medication. Patients must provide a full medical history, including any previous reactions to salads, ragweed, or other vegetables, prior to testing.
No FDA black box warnings for Lettuce are currently listed specifically for the whole food, but the Standardized and Non-Standardized Allergenic Extract class carries a general mandate for a boxed warning regarding Anaphylaxis Risk. This warning emphasizes that extracts can cause sudden, life-threatening allergic reactions and must be administered in settings equipped with emergency resuscitative equipment, including oxygen, IV fluids, and epinephrine.
Lettuce extract does not typically cause sedation. However, if a systemic reaction occurs or if antihistamines are administered to treat a local reaction, the patient should not drive or operate heavy machinery until the effects have fully subsided.
Alcohol consumption should be avoided for 24 hours before and after testing. Alcohol can increase peripheral vasodilation, which may enhance the rate of allergen absorption and potentially worsen a systemic reaction.
There is no withdrawal syndrome associated with Lettuce extract. However, if a patient experiences a systemic reaction, further testing or therapy with the extract must be discontinued until a full safety re-evaluation is performed.
> Important: Discuss all your medical conditions with your healthcare provider before starting Lettuce extract testing.
> Important: Tell your doctor about ALL medications, supplements, and herbal products you are taking, especially those for allergies, blood pressure, or depression.
Patients who are allergic to Ragweed pollen (Ambrosia) often show cross-sensitivity to Lettuce due to shared proteins. This is known as 'Pollen-Food Allergy Syndrome.' Additionally, cross-reactivity with Mugwort and Birch pollen is common. Patients with a known 'Latex-Fruit Syndrome' may also show sensitivity to Lettuce due to the presence of Hevein-like proteins.
> Important: Your healthcare provider will evaluate your complete medical history before prescribing or administering Lettuce extract.
Pregnancy Category C: Animal reproduction studies have not been conducted with Lettuce allergenic extracts. It is also not known whether these extracts can cause fetal harm when administered to a pregnant woman. The primary concern during pregnancy is the risk of a systemic allergic reaction (anaphylaxis) in the mother, which can lead to placental hypoperfusion and fetal distress. Allergy testing and the initiation of immunotherapy are generally postponed until postpartum unless the clinical need is urgent.
It is not known whether the protein components of Lettuce extract are excreted in human milk. Because the systemic absorption of diagnostic extracts is minimal, the risk to the nursing infant is considered low. However, the decision to test should be made after a risk-benefit analysis by the healthcare provider.
Lettuce extract testing is safe for use in children as young as 6 months, provided the child is stable and the procedure is necessary. However, the emotional distress of the procedure and the difficulty of keeping a young child still for 20 minutes must be considered. In children, the volar surface of the back is often used to provide more surface area for testing.
Clinical studies of Lettuce extract did not include sufficient numbers of subjects aged 65 and over to determine whether they respond differently from younger subjects. In general, elderly patients have thinner skin and may have a reduced histamine response, which can lead to smaller wheal sizes. Furthermore, the presence of comorbid cardiovascular disease in this population increases the risk associated with potential anaphylaxis.
No dosage adjustments are required. However, the presence of uremia can cause skin changes that may interfere with the accuracy of the skin prick test.
No dosage adjustments are necessary. Hepatic function does not significantly impact the local immunological response to the extract.
> Important: Special populations require individualized medical assessment to ensure the safety and validity of the diagnostic process.
The pharmacological action of Lettuce extract depends on its application. As an Allergenic Extract, its primary action is the cross-linking of IgE antibodies bound to the high-affinity receptor (FcεRI) on the surface of mast cells and basophils. This cross-linking triggers a signal transduction cascade involving tyrosine kinases, leading to the release of pre-formed mediators like histamine, tryptase, and leukotrienes. This produces the classic Type I hypersensitivity response.
As a Vitamin A [EPC] source, the beta-carotene in Lettuce is cleaved by the enzyme beta-carotene 15,15'-dioxygenase in the intestinal mucosa to form retinal, which is then reduced to retinol. Retinol is essential for the formation of rhodopsin in the retina, supporting vision in low light.
| Parameter | Value |
|---|---|
| Bioavailability | < 1% (Skin Prick); > 90% (Oral Ingestion of nutrients) |
| Protein Binding | N/A (Proteins are degraded) |
| Half-life | 30–60 minutes (Localized mediators) |
| Tmax | 15–20 minutes (Diagnostic response) |
| Metabolism | Proteolysis by local tissue enzymes |
| Excretion | Renal (Metabolites) |
Lettuce extract is classified as a Non-Standardized Plant Allergenic Extract. It shares this class with other vegetable extracts like celery, carrot, and potato. It is distinct from 'Standardized Extracts' (like Grass Pollen or Cat Hair), which have federally mandated potency requirements.
Common questions about Lettuce
Lettuce extract is primarily used as a diagnostic tool by allergists to identify if a patient has a specific allergy to lettuce or related plants. By applying a small amount to the skin during a 'prick test,' doctors can observe the body's immune response in a controlled environment. This is especially helpful for patients who experience itching or swelling after eating salads, a condition sometimes called 'Salad Bowl Syndrome.' Additionally, because lettuce contains precursors to Vitamin A and D, its chemical components are studied for nutritional and pharmacological purposes. It is rarely used for immunotherapy (allergy shots) compared to more common allergens like pollen.
The most common side effects are localized to the area where the test was performed, usually the forearm or the back. Patients typically experience a small, itchy red bump similar to a mosquito bite, which is known as a 'wheal and flare' reaction. This is actually the intended result of the test, as it indicates a positive allergy. Some patients may also experience mild swelling or redness that lasts for a few hours. These symptoms usually peak within 20 minutes and fade away shortly after the test is completed. In some cases, the area may remain slightly tender or itchy for the remainder of the day.
It is strongly recommended to avoid alcohol for at least 24 hours before and after undergoing an allergy test with Lettuce extract. Alcohol acts as a vasodilator, meaning it widens the blood vessels, which can increase the speed at which the allergen enters your system. This might lead to a more severe or unpredictable reaction than would otherwise occur. Furthermore, alcohol can interfere with the body's ability to respond to emergency medications like epinephrine if a serious reaction were to happen. Always inform your doctor if you have consumed alcohol recently before a diagnostic procedure. Following these guidelines ensures the most accurate and safe test results.
Eating lettuce as a food is considered safe and healthy during pregnancy, provided it is thoroughly washed to avoid bacterial contamination. However, clinical testing with Lettuce allergenic extract is generally avoided during pregnancy. The main concern is not the extract itself, but the risk of a systemic allergic reaction (anaphylaxis) during the test. Anaphylaxis can cause a dangerous drop in the mother's blood pressure and reduce oxygen flow to the baby. Because allergy testing is rarely an emergency, most healthcare providers recommend waiting until after delivery to perform these diagnostic procedures. Always consult your obstetrician and allergist before undergoing any medical testing while pregnant.
Allergy test results for Lettuce extract are almost immediate, which is one of the benefits of skin prick testing. After the extract is applied and the skin is pricked, a reaction typically begins to form within 5 to 10 minutes. The healthcare provider will wait exactly 15 to 20 minutes to measure the size of the wheal (the bump) and the flare (the redness). After this 20-minute window, the results are recorded, and the test is considered complete. While the primary reaction happens quickly, doctors ask patients to stay in the clinic for an additional 30 minutes to ensure no delayed systemic reactions occur. This entire process ensures a rapid and reliable diagnosis.
Since Lettuce is typically used as a one-time diagnostic extract rather than a daily medication, there is no risk of withdrawal or 'rebound' effects when you stop exposure. If you are using Lettuce as part of your diet and choose to stop eating it, there are no pharmacological complications. However, if you are undergoing a rare course of Lettuce immunotherapy (allergy shots), you should not stop the treatment without consulting your allergist. Stopping immunotherapy abruptly can halt the progress of your desensitization and may require you to start the process over at a lower dose. For diagnostic testing, there is no 'discontinuation' process needed after the test is over.
Missing a 'dose' of Lettuce extract usually refers to missing a scheduled allergy testing appointment. If this happens, you should simply call your allergist's office to reschedule the procedure. There are no health risks associated with delaying a diagnostic test. However, if you are part of a specialized treatment plan involving Lettuce extracts and you miss an injection, you must contact your doctor immediately. They may need to adjust your next dose to a lower concentration to ensure your safety, as your body's tolerance can change if too much time passes between exposures. Never attempt to 'double up' on an allergenic extract dose.
There is no clinical evidence to suggest that Lettuce, whether consumed as a food or used as a medical extract, causes weight gain. In fact, Lettuce is extremely low in calories and high in water content, making it a staple in weight management diets. From a pharmacological perspective, the allergenic extracts used in testing do not contain the hormones or metabolic-altering compounds that typically lead to weight changes. Some patients may experience temporary localized swelling after a skin test, but this is an inflammatory response, not a gain in body fat. You can discuss any concerns about weight and your diet with a registered dietitian or your primary physician.
Lettuce extract can interact with several types of medications, particularly those that affect your immune system or your heart. Antihistamines are the most common concern, as they will block the results of an allergy test, making it appear as though you aren't allergic when you actually are. More seriously, medications like beta-blockers can make it difficult for doctors to treat you if you have a severe reaction to the test. Other drugs, like certain antidepressants, can also interfere with how your body handles the extract or the emergency medications used to treat reactions. Always provide your allergist with a complete list of your current medications before any testing begins.
In the world of allergenic extracts, the term 'generic' works a bit differently than it does for pills. Lettuce extracts are 'non-standardized,' meaning they are produced by various biological laboratories rather than a single brand-name pharmaceutical company. Different manufacturers may produce Lettuce extracts that vary slightly in their protein concentration, but they are all used for the same diagnostic purposes. You won't typically find a 'brand-name' version of a Lettuce skin test; instead, your allergist will use a high-quality extract from a reputable biological supplier. These extracts are regulated by the FDA to ensure they meet safety and purity standards regardless of the manufacturer.