Side Effects of Diosmin
Diosmin is generally well-tolerated with predominantly mild gastrointestinal side effects, and serious adverse events are rare even at doses up to 2000 mg daily for extended periods.
Common Side Effects
The most frequently reported adverse effects of diosmin are mild and typically do not require discontinuation of therapy 1:
- Gastrointestinal disturbances (most common): Dyspepsia or non-specific mild stomach upset occurs in up to 7% of patients—approximately twice the frequency seen with placebo 1
- Headaches: Commonly reported but generally mild in severity 1
- Abdominal pain and diarrhea: Occur occasionally but are typically self-limited 2
Additional mild effects reported in clinical trials include 1:
- Rash (approximately 1%)
- Lower limb cramping (approximately 2%)
- Nausea, vomiting, and constipation 2
Rare but Serious Adverse Events
While uncommon, several serious adverse effects have been documented in case reports and warrant clinical awareness:
Hematologic and Vascular Events
- Enzyme elevation: Rare cases of increased creatine phosphokinase (CPK) and lactic dehydrogenase (LDH) have been reported, potentially related to exaggerated adrenergic activity causing peripheral vasoconstriction and ischemic damage 3
- Hemorrhagic complications: One case report documented spontaneous intraventricular hemorrhage in a patient on chronic diosmin therapy combined with warfarin, possibly due to diosmin's platelet aggregation inhibition and effects on venous tone 4
Other Rare Events
Infrequent adverse events reported include 1:
- Inguinal pain
- Cystitis
- Asthenia (weakness)
- Metrorrhagia and menometrorrhagia (abnormal uterine bleeding)
Safety Profile Across Populations
Elderly patients: The incidence of adverse events in patients ≥70 years of age is not significantly different from younger populations 1
Patients with comorbidities: Adverse event rates are not higher in patients with concomitant hypertension, atherosclerosis, diabetes, neurologic/psychiatric disease, or alcoholism 1
High-dose therapy: Clinical studies demonstrate that diosmin at doses up to 2000 mg daily for 4 months shows no significant abnormalities in complete blood counts, fibrinogen, liver enzymes (ALT/AST), renal function (urea/creatinine), urinalysis, or blood pressure 5
Clinical Monitoring Considerations
Cardiovascular effects: No adverse cardiovascular effects have been observed in clinical trials; small decreases in both systolic and diastolic blood pressure have been noted in several studies 1
Metabolic parameters: No effects on blood glucose, insulin levels, or insulin resistance have been documented 1
Renal function: Interestingly, statistically significant decreases in creatinine levels have been observed in several clinical trials, suggesting potential renoprotective effects rather than toxicity 1, 6
Important Clinical Caveats
- Drug interactions: Patients on anticoagulation therapy should be monitored carefully, as diosmin inhibits platelet aggregation and may potentiate bleeding risk when combined with warfarin or other anticoagulants 4
- Myalgia: If patients develop leg pain or myalgia during therapy, consider checking CPK levels and discontinuing diosmin if elevated 3
- Individual predisposition: Rare adverse effects may occur due to individual susceptibility, particularly related to microcirculatory effects 3
Pregnancy and Reproductive Safety
Diosmin has been tested in pregnancy during the third trimester and 4 weeks postpartum at 900 mg daily, showing no effects on pregnancy, fetal development, birth weight, or infant growth and feeding 1. Teratogenicity studies in animals at doses up to 100 mg/kg/day showed no differences in fetal formation, litter size, weight gain, or developmental milestones 1.