According to the FDA (2024), Achillea Millefolium is classified as a Non-Standardized Plant Allergenic Extract used for the diagnosis and treatment of Type I hypersensitivity.
A clinical review in the Journal of Allergy and Clinical Immunology (2022) emphasizes that all allergenic extracts carry a risk of anaphylaxis, requiring a 30-minute post-injection observation period.
Achillea Millefolium belongs to the Asteraceae family, and cross-reactivity with ragweed and chamomile is common in sensitized individuals (NIH, 2023).
The use of beta-blockers is a major precaution for patients receiving Achillea Millefolium because they can antagonize the effects of epinephrine during emergencies (DailyMed, 2024).
Allergen immunotherapy with Achillea Millefolium has been shown to induce the production of IgG4 'blocking antibodies' (World Allergy Organization, 2023).
Standardized skin testing protocols require the discontinuation of H1-antihistamines for at least 3 to 7 days prior to using Achillea Millefolium extract (American Academy of Allergy, Asthma & Immunology, 2024).
Achillea Millefolium extracts must be stored between 2°C and 8°C to prevent protein denaturation and loss of potency (FDA Labeling, 2024).
The FDA-mandated black box warning for this class of drugs highlights that patients with unstable asthma are at the highest risk for fatal systemic reactions.
This page is for informational purposes only and does not replace medical advice. Before using any prescription or over-the-counter medication for Millefolium, you must consult a qualified healthcare professional.
Achillea Millefolium, commonly known as Yarrow, is utilized in clinical medicine as a Non-Standardized Plant Allergenic Extract for the diagnosis and treatment of Type I hypersensitivity reactions (allergies).
💊Usage & Dosage
Adult Dosage
Dosage for Achillea Millefolium is highly individualized and must be determined by an allergy specialist based on the patient's sensitivity levels.
Diagnostic Testing: For percutaneous (prick) testing, a single drop of the extract is applied to the skin, and a sterile lancet is used to puncture the epidermis. For intradermal testing, 0.02 mL to 0.05 mL of a highly diluted extract (usually 1:100 to 1:1000 v/v) is injected into the dermis.
Immunotherapy: Dosing begins with a 'build-up phase.' This usually starts with a very low dose (e.g., 0.05 mL of a 1:100,000 dilution) administered subcutaneously once or twice weekly. The dose is gradually increased until a 'maintenance dose' is reached, which is the highest dose the patient can tolerate without significant systemic reactions. Maintenance doses are typically administered every 2 to 4 weeks.
Pediatric Dosage
Achillea Millefolium extracts are generally considered safe for use in children, provided the child is old enough to cooperate with the testing and the risks of immunotherapy are outweighed by the benefits.
Dosing: Pediatric dosing follows the same weight-independent, sensitivity-dependent titration as adult dosing. However, extreme caution is advised in very young children (under age 5) due to the difficulty of communicating early symptoms of a systemic reaction.
Dosage Adjustments
Renal Impairment
No dosage adjustments are typically required for patients with renal impairment, as the extract is not cleared via traditional renal pathways. However, the patient's overall health must be stable.
Hepatic Impairment
No dosage adjustments are required for patients with hepatic impairment. The metabolic processing of allergenic proteins occurs via cellular proteolysis rather than hepatic enzyme systems.
Elderly Patients
Caution is advised in elderly patients, particularly those with underlying cardiovascular disease. The risk of adverse reactions to epinephrine (which is required if a systemic reaction occurs) must be considered before administering Achillea Millefolium extracts.
How to Take Achillea Millefolium
Achillea Millefolium extracts are never for self-administration at home. They must be administered in a clinical setting equipped with emergency resuscitation equipment.
Administration: Subcutaneous injections should be given in the outer aspect of the upper arm. The site should not be massaged after injection to prevent rapid absorption.
Observation: Patients MUST remain in the clinic for at least 30 minutes following any injection to monitor for signs of anaphylaxis.
Storage: Extracts must be stored in a refrigerator at 2°C to 8°C (36°F to 46°F). Do not freeze. Freezing can denature the allergenic proteins, rendering the extract ineffective or potentially dangerous.
Missed Dose
If a dose of immunotherapy is missed, do not double the next dose.
If the delay is short (e.g., 1 week), the previous dose may be repeated.
If the delay is long (e.g., several weeks), the dose may need to be reduced to ensure safety. Your allergist will follow a specific 'gap schedule' to safely resume treatment.
Overdose
An 'overdose' in the context of allergenic extracts refers to an injection of a dose higher than the patient's current tolerance level.
Signs: Severe local swelling, generalized hives (urticaria), wheezing, shortness of breath, drop in blood pressure, or fainting.
Action: Immediate administration of epinephrine and emergency medical support. If you believe you are experiencing a reaction after leaving the clinic, call 911 or go to the nearest emergency room immediately.
> Important: Follow your healthcare provider's dosing instructions exactly. Do not adjust your dose or skip appointments without medical guidance.
⚠️Side Effects
Common Side Effects (>1 in 10)
Most patients receiving Achillea Millefolium extracts will experience some form of local reaction. These are generally not dangerous but can be uncomfortable.
Local Redness (Erythema): The skin around the injection or test site may turn red. This usually appears within minutes and may last for several hours.
Itching (Pruritus): Intense itching at the site of administration is very common as histamine is released locally.
Swelling (Wheal): A raised, hive-like bump at the site. This is the expected result of a diagnostic test but should be monitored if it exceeds 2-3 inches in diameter during immunotherapy.
Tenderness: The area may feel sore or warm to the touch for 24 to 48 hours.
🔴Warnings
Important Safety Information
Achillea Millefolium extract is a potent biological agent. Its use is restricted to diagnostic and therapeutic protocols under the direct supervision of a physician. It is not a 'herbal supplement' when used in this extract form; it is a regulated drug product. Patients must be honest about their current health status, especially any respiratory or heart conditions, before each injection.
Black Box Warnings
No FDA black box warnings for Achillea Millefolium? No, this is incorrect. As a member of the allergenic extract class, it does carry the standard class-wide black box warning. The warning emphasizes that Achillea Millefolium can cause anaphylaxis, which may be fatal. It must be administered in a facility equipped with oxygen, IV fluids, and epinephrine. Patients must be monitored for 30 minutes post-injection.
Major Precautions
Allergic Reactions / Anaphylaxis Risk
🔄Interactions
Contraindicated Combinations (Do Not Use Together)
While there are few absolute contraindications for other drugs, the following combinations create extreme risk:
Beta-Blockers (e.g., Propranolol, Metoprolol): These medications are used for high blood pressure and heart conditions. They are contraindicated because they block the effects of epinephrine. If a patient on a beta-blocker has an anaphylactic reaction to Achillea Millefolium, the emergency treatment (epinephrine) may not work, leading to a potentially fatal outcome.
Serious Interactions (Monitor Closely)
ACE Inhibitors (e.g., Lisinopril, Enalapril): Some studies suggest that patients on ACE inhibitors may be at a higher risk for more severe systemic reactions to allergenic extracts.
MAO Inhibitors (e.g., Phenelzine): These can potentiate the effects of epinephrine, leading to dangerous spikes in blood pressure if an allergic reaction is treated.
🚫Contraindications
Absolute Contraindications
Achillea Millefolium extract must NEVER be used in the following circumstances:
1Severe or Uncontrolled Asthma: Patients with a Forced Expiratory Volume (FEV1) consistently below 70% of predicted values are at an unacceptable risk of fatal bronchospasm during a reaction.
2Known Hypersensitivity to Extract Components: If a patient has had a previous life-threatening reaction to the specific components of the Achillea Millefolium vial (including the glycerin or phenol preservatives), they should not receive it.
3Beta-Blocker Therapy: Due to the inability to treat anaphylaxis effectively with epinephrine.
👥Special Populations
Pregnancy
Achillea Millefolium is categorized similarly to other allergenic extracts (FDA Category C). There are no adequate and well-controlled studies in pregnant women.
Risks: The primary risk to the fetus is maternal anaphylaxis, which can cause uterine contractions and fetal hypoxia (lack of oxygen).
Clinical Practice: Allergists generally do not initiate Achillea Millefolium immunotherapy during pregnancy. If a woman is already on a stable maintenance dose and becomes pregnant, the doctor may choose to continue the dose or reduce it, but they will not increase the dose until after delivery.
Breastfeeding
It is not known whether the allergenic components of Achillea Millefolium are excreted in human milk. However, because these are large proteins and administered in minute quantities, it is highly unlikely they would be absorbed intact by the nursing infant. The risk-benefit ratio is generally favorable for continuing immunotherapy while breastfeeding.
🧬Pharmacology
Mechanism of Action
Achillea Millefolium allergenic extract acts as a specific antigen challenge. At the molecular level, the extract contains various proteins (antigens) from the Yarrow plant. When these antigens enter the body of a sensitized individual, they bind to IgE antibodies that are already attached to the high-affinity IgE receptor (FcεRI) on mast cells and basophils. This binding causes the receptors to cluster (cross-link), which activates an intracellular signaling cascade involving tyrosine kinases (like Syk). This results in the rapid release of pre-formed mediators (histamine) and the synthesis of new mediators (leukotrienes) that cause the allergic response.
Pharmacodynamics
Onset of Action: For skin testing, the 'wheal and flare' reaction typically peaks within 15 to 20 minutes. This is known as the 'immediate phase' reaction.
Late-Phase Reaction: In some patients, a second wave of swelling and inflammation can occur 4 to 12 hours after administration, caused by the recruitment of eosinophils and other inflammatory cells to the site.
Frequently Asked Questions
Common questions about Millefolium
What is Achillea Millefolium used for?
Achillea Millefolium extract is used in clinical allergy practice for two primary purposes: diagnosis and treatment. In diagnosis, it is applied to the skin to identify if a patient has a specific allergy to Yarrow plant proteins, which often cause seasonal hay fever. In treatment, it is used in allergen immunotherapy (allergy shots) to gradually desensitize the patient's immune system. This process involves giving small, increasing doses of the extract over several years. The goal is to reduce or eliminate the patient's allergic symptoms when they are naturally exposed to Yarrow pollen in the environment.
What are the most common side effects of Achillea Millefolium?
The most common side effects are localized to the site where the extract was administered. Patients frequently experience redness, itching, and a raised bump (wheal) at the injection or skin-test site. These reactions are usually mild and resolve within a few hours to a couple of days. Some patients may also experience a 'late-phase' reaction where the area becomes swollen and warm several hours later. While these local effects are common, they are generally not dangerous and can be managed with cold compresses or over-the-counter antihistamines if approved by your doctor.
Can I drink alcohol while taking Achillea Millefolium?
It is strongly recommended to avoid alcohol for several hours before and after receiving an Achillea Millefolium injection. Alcohol causes your blood vessels to dilate (expand), which can increase the speed at which the allergen is absorbed into your bloodstream. This rapid absorption can increase the risk of a systemic allergic reaction or make a reaction more severe if it occurs. Additionally, alcohol can sometimes mask the early symptoms of an allergic reaction, such as lightheadedness or flushing. Always wait until the observation period is over and you feel completely normal before consuming alcohol.
Is Achillea Millefolium safe during pregnancy?
Achillea Millefolium is generally not started as a new treatment during pregnancy. The main concern is not the extract itself, but the risk of a severe allergic reaction (anaphylaxis) in the mother, which could deprive the fetus of oxygen. However, if a patient is already on a stable 'maintenance' dose of allergy shots and becomes pregnant, many allergists will continue the treatment because the risk of a reaction is much lower at that stage. You must inform your allergist immediately if you become pregnant so they can adjust your treatment plan. Decisions are made on a case-by-case basis to ensure the safety of both mother and baby.
How long does it take for Achillea Millefolium to work?
When used for diagnostic testing, Achillea Millefolium works almost immediately, with results visible within 15 to 20 minutes. However, when used for immunotherapy (allergy shots), the process is much slower. Most patients begin to notice a reduction in their allergy symptoms during the first year of treatment, usually once they reach their 'maintenance dose.' For the best and most lasting results, the treatment usually continues for three to five years. This long-term approach is necessary to fundamentally retrain the immune system to tolerate the allergen.
Can I stop taking Achillea Millefolium suddenly?
Yes, you can stop taking Achillea Millefolium shots suddenly without experiencing physical withdrawal symptoms like those seen with some other medications. However, stopping treatment prematurely means your immune system will likely revert to its previous allergic state. This means your hay fever or allergy symptoms will probably return over the following months. If you are finding the schedule difficult or are concerned about side effects, talk to your allergist. They may be able to adjust your dose or frequency rather than stopping the treatment entirely.
What should I do if I miss a dose of Achillea Millefolium?
If you miss a scheduled allergy shot, do not attempt to 'make it up' by taking a higher dose later. Contact your allergist's office as soon as possible to reschedule. Depending on how long it has been since your last shot, your doctor may need to repeat your last dose or even reduce the dose slightly for safety. This is because your level of tolerance can decrease if there is too much time between injections. Following a consistent schedule is the most effective way to reach your treatment goals safely.
Does Achillea Millefolium cause weight gain?
There is no clinical evidence to suggest that Achillea Millefolium allergenic extract causes weight gain. The extract consists of natural proteins and is administered in very small quantities that do not affect your metabolism or appetite. If you experience weight changes while on this treatment, it is likely due to other factors such as lifestyle changes, other medications (like oral steroids sometimes used for allergies), or an underlying health condition. Always discuss significant weight changes with your primary care physician.
Can Achillea Millefolium be taken with other medications?
Achillea Millefolium can be taken with many medications, but there are critical exceptions. You must avoid beta-blockers (often used for heart conditions or blood pressure) because they can prevent life-saving epinephrine from working if you have a severe reaction. Additionally, you must stop taking antihistamines several days before a skin test, as they will block the reaction and lead to incorrect results. Always provide your allergist with a complete list of all prescriptions, over-the-counter drugs, and herbal supplements you are using to ensure your safety.
Is Achillea Millefolium available as a generic?
Achillea Millefolium is a biological product rather than a synthetic drug, so the term 'generic' is not used in the traditional sense. Instead, different biological manufacturers produce their own versions of Yarrow allergenic extract. While these extracts are all derived from the same plant, they are 'non-standardized,' meaning the exact potency can vary between different manufacturers. For this reason, allergists usually prefer to keep a patient on the extract from the same manufacturer throughout their treatment to ensure consistent dosing and safety.
Similar Medications
Other drugs with the same active ingredient (Achillea Millefolium)
Large Local Reactions: Swelling that extends beyond the immediate injection site, sometimes involving the entire upper arm. This may require an adjustment in the immunotherapy schedule.
Fatigue: Some patients report feeling unusually tired for a few hours after an immunotherapy injection.
Headache: Mild tension-type headaches have been reported following administration.
Nasal Congestion: A temporary 'flare' of allergy symptoms, such as sneezing or a runny nose.
Rare Side Effects (less than 1 in 100)
Systemic Urticaria: Hives appearing on parts of the body far from the injection site.
Angioedema: Swelling of the deeper layers of the skin, often around the eyes or lips.
Persistent Granuloma: A small, hard knot under the skin at the injection site that may take weeks to resolve.
Serious Side Effects — Seek Immediate Medical Attention
> Warning: Stop taking Achillea Millefolium and call your doctor immediately if you experience any of these symptoms of anaphylaxis.
Wheezing or Difficulty Breathing: Suggests bronchospasm (narrowing of the airways).
Throat Tightness: A feeling that the throat is closing or difficulty swallowing (laryngeal edema).
Hypotension: A sudden drop in blood pressure, which may feel like dizziness, lightheadedness, or fainting.
Rapid or Weak Pulse: Signs of cardiovascular distress.
Nausea and Vomiting: Systemic allergic reactions can sometimes manifest as sudden gastrointestinal distress.
Cyanosis: A bluish tint to the lips or fingernails, indicating a lack of oxygen.
Long-Term Side Effects
There are no known long-term 'toxic' effects of Achillea Millefolium extracts because they are biological proteins. However, the primary long-term risk is the development of new sensitivities or the rare occurrence of 'serum sickness,' although this is extremely uncommon with modern, purified extracts. The goal of long-term use is actually a positive 'side effect'—the permanent reduction of allergic symptoms.
Black Box Warnings
Achillea Millefolium, like all allergenic extracts, carries a FDA-mandated Black Box Warning regarding the risk of severe systemic reactions.
Summary: Allergenic extracts can cause severe life-threatening systemic reactions, including anaphylaxis. Patients with unstable asthma are at increased risk. Extracts should only be administered by healthcare providers prepared to manage anaphylaxis. Patients should be observed for at least 30 minutes. Patients taking beta-blockers may be unresponsive to epinephrine, the standard treatment for anaphylaxis.
Report any unusual symptoms to your healthcare provider, even if they seem minor at the time.
: This is the primary risk. Anaphylaxis can occur even in patients who have previously tolerated the extract. Risk factors include high sensitivity levels, rapid dose escalation, and high pollen counts in the environment during the time of injection.
Asthma: Patients with symptomatic or poorly controlled asthma are at a significantly higher risk for a fatal reaction. Immunotherapy should be withheld if the patient is experiencing an asthma flare.
Cardiovascular Disease: Patients with unstable angina or recent myocardial infarction may not tolerate the physiological stress of a systemic reaction or the effects of the epinephrine required to treat it.
Autoimmune Disorders: Caution is advised, as immunotherapy stimulates the immune system, which could theoretically exacerbate certain autoimmune conditions.
Monitoring Requirements
Pre-Injection Assessment: Before every dose, the provider must check for any late-phase reactions from the previous dose and ensure the patient is not currently ill or experiencing asthma symptoms.
Peak Flow Monitoring: For asthmatic patients, a peak flow meter may be used to ensure lung function is stable before administration.
Observation Period: A mandatory 30-minute wait in the clinic after every injection.
Driving and Operating Machinery
Achillea Millefolium generally does not cause drowsiness. However, if a patient experiences a systemic reaction or receives epinephrine, they should not drive until cleared by a physician.
Alcohol Use
Alcohol should be avoided for several hours before and after an injection. Alcohol causes vasodilation (widening of blood vessels), which can increase the rate of allergen absorption and potentially increase the risk or severity of a systemic reaction.
Discontinuation
If immunotherapy is discontinued, the patient will slowly lose the immunological tolerance they have built up. There is no 'withdrawal syndrome,' but allergic symptoms will likely return to their baseline levels over several months.
> Important: Discuss all your medical conditions with your healthcare provider before starting Achillea Millefolium.
Tricyclic Antidepressants (e.g., Amitriptyline): Similar to MAOIs, these can increase the cardiovascular risks associated with epinephrine administration.
Moderate Interactions
Antihistamines (e.g., Loratadine, Cetirizine): These drugs must be stopped several days (usually 3-7 days) before diagnostic skin testing. Antihistamines block the H1 receptors, which prevents the 'wheal and flare' reaction, leading to a false-negative test result. They do not need to be stopped for immunotherapy injections.
H2 Blockers (e.g., Famotidine): May also partially mask skin test results and should be discontinued before testing.
Food Interactions
Cross-Reactive Foods: Achillea Millefolium is in the Asteraceae family. Patients sensitive to Yarrow may experience 'Oral Allergy Syndrome' when eating related foods like sunflower seeds, artichokes, or chamomile tea. This is not a direct drug-food interaction but a related immunological phenomenon.
Alcohol: As noted, alcohol increases blood flow to the skin and can accelerate allergen absorption.
Herbal/Supplement Interactions
Chamomile and Echinacea: These plants are in the same family as Achillea Millefolium. Taking these supplements while undergoing testing or immunotherapy may increase the total 'allergen load' on the immune system, potentially increasing the risk of a reaction.
St. John's Wort: May increase sensitivity to sunlight, which could theoretically worsen local skin reactions.
Lab Test Interactions
Skin Prick Tests: As mentioned, antihistamines and certain antidepressants will interfere with the results.
Serum IgE Tests: Achillea Millefolium treatment will eventually lead to changes in specific IgE and IgG4 levels in the blood; this is an intended effect of the therapy and not an 'interference.'
> Important: Tell your doctor about ALL medications, supplements, and herbal products you are taking.
Relative Contraindications
These conditions require a careful risk-benefit analysis by the physician:
Pregnancy: While not a direct contraindication, starting new immunotherapy during pregnancy is generally avoided due to the risk of anaphylaxis-induced fetal hypoxia. Maintenance doses may sometimes be continued.
Active Infection or Fever: Immunotherapy should be delayed until the patient is well, as an active immune system may be more 'primed' for a systemic reaction.
Severe Atopic Dermatitis: May make the interpretation of skin tests impossible.
Cross-Sensitivity
Patients who are allergic to Achillea Millefolium are highly likely to be cross-sensitive to other members of the Asteraceae family. This includes:
Ragweed (Ambrosia)
Daisies and Marigolds
Chrysanthemums
Dandelions
Chamomile
If you have had a severe reaction to any of these plants, you must inform your doctor before Achillea Millefolium testing.
> Important: Your healthcare provider will evaluate your complete medical history before prescribing Achillea Millefolium.
Pediatric Use
Achillea Millefolium is used in children as young as 5 years old.
Considerations: The efficacy is similar to that in adults. The primary concern is the child's ability to report early symptoms of a reaction (e.g., an 'itchy throat' or 'funny feeling').
Growth: There is no evidence that allergenic extracts affect growth or development in children.
Geriatric Use
In patients over 65, the decision to use Achillea Millefolium must be made cautiously.
Cardiac Reserve: Older patients are more likely to have underlying heart disease, making them less able to survive a systemic reaction.
Polypharmacy: The higher likelihood of being on beta-blockers or ACE inhibitors increases the risk profile.
Clearance: While renal clearance is not an issue, the overall physiological resilience of the patient is a key factor.
Renal Impairment
No specific studies have been conducted in patients with renal impairment. However, since the proteins are degraded by local and systemic proteases into amino acids, renal function does not significantly impact the drug's safety or efficacy.
Hepatic Impairment
No adjustments are required. The metabolic pathway for allergenic extracts does not involve the liver's cytochrome P450 system.
> Important: Special populations require individualized medical assessment and close monitoring.
Duration of Effect: A single diagnostic test has no lasting effect. However, a full course of immunotherapy (3-5 years) can result in immunological tolerance that lasts for many years or even a lifetime.
| Protein Binding | Primarily binds to IgE and IgG4 antibodies |
| Half-life | Proteins are degraded within hours/days by proteases |
| Tmax | 15-20 minutes for skin reaction |
| Metabolism | Cellular proteolysis |
| Excretion | Not excreted as an intact drug |
Chemical Information
Composition: A complex mixture of water-soluble proteins, glycoproteins, and polysaccharides extracted from Achillea millefolium.
Solubility: Highly soluble in aqueous solutions; typically provided in a phosphate-buffered saline or 50% glycerin solution.
Molecular Weight: Varies widely depending on the specific proteins (typically 10 kDa to 70 kDa).
Drug Class
Achillea Millefolium is a Non-Standardized Plant Allergenic Extract. It belongs to the broader class of Immunotherapy Agents. Related medications include extracts for Ragweed, Timothy Grass, and various tree pollens used in the same diagnostic and therapeutic manner.