Garlic Pearls Side Effects
Garlic supplements can cause gastrointestinal irritation, bleeding complications, and drug interactions, particularly with anticoagulants, and should be discontinued 7-10 days before surgery. 1, 2
Gastrointestinal Effects
- Stomach pain and gas are common side effects, especially at higher doses 1
- Raw garlic powder preparations can cause severe gastric mucosal damage including erosion, while aged garlic extract appears safer 3
- Enteric-coated garlic products may cause loss of epithelial cells in the ileum when administered orally 3
- "Garlic breath" and body odor are the most consistently documented complaints in clinical trials 4
Bleeding and Coagulation Risks
- Garlic supplements alter bleeding time and should not be used concomitantly with warfarin or other anticoagulants 1
- Inhibition of platelet function has been documented in patients consuming garlic supplements 1
- Case reports have documented increased bleeding risk with garlic use 1, 4
- Garlic should be stopped 7-10 days before surgery due to prolonged bleeding time 2
- The mechanism involves inhibition of platelet aggregation and alteration of the coagulation cascade 5
Drug Interactions
- Garlic inhibits cytochrome P450 enzymes, leading to potential drug interactions 1
- May enhance the pharmacological effect of anticoagulants (warfarin, fluindione) 4
- Can reduce the efficacy of anti-AIDS drugs, specifically saquinavir 4
- Should not be used with feverfew, ginkgo biloba, ginger, or ginseng due to additive bleeding risk 1
Allergic and Dermatologic Reactions
- Allergic reactions may occur, though garlic appears generally safe 6
- Documented reactions include allergic contact dermatitis, generalized urticaria, angioedema, pemphigus, anaphylaxis, and photoallergy 4
- Fresh garlic applied to skin can cause burns, particularly under occlusive dressings 4
Clinical Context
- The American College of Cardiology Foundation/American Heart Association explicitly recommends against using garlic supplements for cardiovascular risk reduction 1
- The American Cancer Society states insufficient evidence exists to support garlic's role in cancer prevention 5, 1
- Despite traditional use for infections, diabetes, and heart disease, clinical evidence for efficacy remains far from compelling 6
- Garlic consumption by nursing mothers modifies infant behavior during breastfeeding 4