Botulinum toxin (BoNT) injections have become one of the most popular cosmetic treatments worldwide, offering solutions for wrinkles, fine lines, and even therapeutic applications such as migraine relief. In the United Kingdom alone, nearly a million BoNT treatments are administered annually. Despite the widespread popularity of these procedures, safety considerations remain crucial, particularly for patients with pre-existing medical conditions. A recent large-scale survey conducted in the UK in 2024 has provided new insights into the association between chronic health conditions and adverse effects from BoNT injections. Understanding these findings is essential for patients, healthcare providers, and policymakers to ensure both safe and effective treatments.
Botulinum toxins are neurotoxins that temporarily block the release of acetylcholine at the motor endplate, reducing muscle contraction. Of the seven identified types, only types A and B are used in clinical practice. BoNT type A is the most commonly administered form for cosmetic purposes and is available in several commercial formulations, including Botox, Dysport, Xeomin, Jeuveau, and Letybo. Beyond cosmetic applications, BoNT is used therapeutically for conditions such as chronic migraine, spasticity, and hyperhidrosis.
While the effectiveness of BoNT is well-established, adverse events remain a documented concern. Commonly reported side effects include bruising, swelling, headache, nausea, ptosis, muscle weakness, dry mouth, facial asymmetry, and mood changes. Although these complications are often mild and temporary, their frequency and severity can vary significantly based on an individual’s underlying health conditions. This variation underlines the importance of understanding who may be at greater risk for post-treatment complications.
The UK survey, conducted from January to April 2025, aimed to explore the relationship between existing medical conditions and adverse events following BoNT injections. The study involved 919 adult participants who had received BoNT for cosmetic purposes. Researchers collected information on age, gender, chronic physical and mental health conditions, and the type and severity of adverse effects experienced. The primary objective was to identify conditions that significantly increase the risk of complications, helping practitioners tailor treatment plans and provide more informed guidance to patients.
This investigation was a cross-sectional survey distributed across Great Britain and Northern Ireland. Participants were recruited through social media platforms, cosmetic patient networks, and press releases. The survey consisted of 34 questions that collected data on medical history, mental health, acute and long-term BoNT complications, and demographic information. Participation was voluntary and anonymous, with informed consent obtained prior to survey completion. Ethical approval was granted by Anglia Ruskin University.
To assess the relationships between pre-existing health conditions and post-BoNT adverse events, researchers applied multivariable logistic regression models. This allowed them to determine the odds of experiencing specific side effects based on the presence of conditions such as skin disorders, diabetes, thyroid disease, chronic migraines, and psychiatric disorders. Age was included as a categorical variable to account for potential differences in complication rates across age groups.
The survey revealed several important associations between chronic health conditions and BoNT complications. While the majority of participants were female (91%), the study included a wide age range, from 18 to over 75 years, with a mean age of 38.6 years.
1. Nausea
The strongest associations were observed for nausea following BoNT injections. Patients with type 1 diabetes had significantly higher odds of experiencing nausea, potentially due to underlying autonomic dysfunction common in diabetes. Similarly, chronic migraine sufferers, those with thyroid disorders, and individuals with skin conditions reported higher incidences of nausea. These findings suggest that systemic disease may influence gastrointestinal sensitivity and post-procedural responses.
2. Headache
Headaches were more common in patients with thyroid disorders, cataracts, anxiety, and other cardiac conditions. The links with anxiety and older age likely reflect both psychophysiological factors and tissue fragility, while thyroid-related immune dysregulation may amplify susceptibility to neurological symptoms.
3. Injection Site Reactions
Pain, bruising, and swelling at the injection site were particularly prevalent among patients with anxiety, obesity, thyroid disease, cataracts, urinary incontinence, and mental health conditions. Anxiety may heighten pain perception, while obesity and age-related vascular changes increase the likelihood of bruising. Thyroid dysfunction may further impair tissue integrity, making even minor trauma more noticeable. These findings reinforce the need for careful technique, pre-treatment screening, and patient counseling.
4. Dry Mouth and Facial Asymmetry
Individuals with skin disease or chronic allergy were more likely to experience dry mouth and facial asymmetry. Local autonomic inhibition near salivary glands and periorbital tissue changes may exacerbate these effects. Chronic allergy was also associated with persistent ptosis, likely due to periorbital edema reducing the anatomical margin for levator compromise. Proper injection planning and conservative dosing can mitigate these risks.
5. Neuromuscular Complications
Muscle weakness, loss of facial expression, and localized atrophy were more common among patients with prior injuries, thyroid disorders, chronic migraine, cataracts, and chronic allergies. Prior injury may predispose patients to asymmetry and heightened sensitivity to BoNT’s paralytic effects. Chronic migraine and thyroid disease likely amplify muscle atrophy due to cumulative dosing and underlying tissue fragility. BoNT resistance, while rare, was associated with angina, chronic constipation, and renal disease, suggesting systemic conditions may influence perceived efficacy.
6. Psychological Effects
Body dysmorphic disorder and obsessive appearance-related thoughts were significantly associated with renal disease and prior physical injury. Anxiety and depression showed complex relationships with adverse outcomes, reflecting both methodological factors and potential psychophysiological mechanisms. These findings emphasize the importance of pre-treatment psychological assessment to identify patients at risk of dissatisfaction or exacerbated mental health symptoms.
The survey highlights that BoNT is not a routine cosmetic procedure but a medical intervention with meaningful systemic implications. Patients with autoimmune, endocrine, neurological, or psychiatric conditions are at higher risk for complications. Practitioners should conduct thorough medical and psychological histories, adjust dosing strategies, and provide anticipatory guidance to patients with chronic health conditions.
For injection site complications, techniques such as slow administration, fine needles, and immediate compression may reduce bruising. Systemic side effects, including nausea, headache, and dry mouth, warrant additional counseling and post-treatment follow-up. Patients with neuromuscular vulnerabilities, prior injuries, or chronic migraines may require dose modifications and anatomical considerations to prevent muscle weakness, atrophy, and asymmetry.
Psychological screening is equally important. Body dysmorphic disorder and obsessive preoccupation with appearance are recognized contraindications for BoNT treatment. Early identification can prevent repeated procedures, emotional distress, and potential medico-legal complications.
Given the complexity of patient risk profiles, the survey supports stricter regulation of BoNT administration in the UK. Suggested measures include:
These policies aim to enhance patient safety, reduce preventable complications, and ensure that BoNT remains a medically supervised intervention rather than a cosmetic commodity.
Several limitations of the study should be acknowledged. The survey relied on self-reported data, which may be affected by recall bias or subjective perception of adverse events. The cross-sectional design precludes causal inference, and the study did not account for BoNT dosing, injection technique, or concurrent medications. Additionally, the sample was predominantly female and self-selected, potentially limiting generalizability. Despite these constraints, the study provides the largest patient-reported dataset on BoNT safety in the UK to date and offers valuable insights into the influence of chronic health conditions on treatment outcomes.
This UK study demonstrates that pre-existing medical conditions significantly influence the risk and type of complications following BoNT injections. Autoimmune disorders, thyroid disease, type 1 diabetes, chronic migraine, psychiatric conditions, and prior physical injuries all increase susceptibility to systemic, local, and neuromuscular adverse effects.
These findings reinforce that BoNT is a medical intervention requiring careful patient selection, expert anatomical knowledge, and psychological assessment. Patients and providers must recognize that even commonly performed cosmetic procedures carry medical consequences, particularly in the presence of chronic health conditions. Policymakers should use this evidence to implement stricter regulations, limiting BoNT administration to qualified healthcare professionals and ensuring patient safety remains paramount.
By acknowledging the complex interplay between chronic illness, psychiatric status, and BoNT treatment outcomes, the aesthetic medicine community can improve both safety and satisfaction. The syringe is a medical instrument with consequences that extend beyond cosmetic improvement, and its use should reflect that reality.
Ravindran R, Rahmati M, López-Gil JF, Yon DK, Pizzol D, Gawronska J, Richardson F, Keyes H, Barnett Y, Butler L, et al. The association between existing health conditions and adverse events from botulinum toxins: findings from a UK cross-sectional survey in 2024. Aesthetic Surgery Journal. 2025;45(10):1–23.
This blog is for informational purposes only. It does not constitute medical advice and should not be used as a substitute for professional consultation with a qualified healthcare provider. Patients considering BoNT injections should consult a licensed medical professional for personalized assessment and guidance based on their individual health status.
