Ginger

• Nausea and vomiting in pregnancy (NVP): Multiple randomized trials and meta-analyses indicate ginger modestly reduces nausea severity and vomiting episodes versus placebo; effect size is small-to-moderate and generally well tolerated (evidence: strong for short-term use at low doses).
• Postoperative nausea and vomiting (PONV): Systematic reviews suggest ginger may reduce risk or severity when used before anesthesia, typically as an adjunct to standard antiemetics; results are mixed across trials (evidence: moderate).
• Chemotherapy-induced nausea (CINV): Meta-analyses show small reductions in acute nausea when ginger is added to antiemetic regimens; effects on vomiting and delayed nausea are inconsistent (evidence: moderate/mixed).
• Functional dyspepsia and gastric motility: Small RCTs show ginger can accelerate gastric emptying and improve upper GI symptoms in some individuals (evidence: emerging to moderate).
• Osteoarthritis pain: Systematic reviews of RCTs report small improvements in pain and disability versus placebo; benefits may take several weeks and GI adverse effects can occur (evidence: moderate).
• Primary dysmenorrhea: Several RCTs and meta-analyses suggest ginger reduces menstrual pain versus placebo and may be comparable to NSAIDs in some studies; many trials are small (evidence: moderate).
• Metabolic markers: Meta-analyses in adults (including type 2 diabetes) show modest improvements in fasting glucose, HbA1c, triglycerides, and LDL-C; heterogeneity is high (evidence: moderate).

Common (generally mild; often dose-related, especially >1–2 g/day dried equivalent): heartburn/acid reflux, abdominal discomfort, gas/belching, diarrhea, mouth/throat irritation. In clinical trials, overall adverse events are usually similar to placebo, with GI symptoms reported in up to ~5–10%. Less common: headache, mild sedation or dizziness, skin rash (topical use). Rare but serious: bleeding events (especially when combined with anticoagulant/antiplatelet drugs), allergic reactions. Individuals with gallstones may experience biliary colic (rare; based largely on case reports/traditional caution). Pregnancy/lactation: Short-term use up to ~1 g/day for NVP appears well tolerated in studies without increased risk of congenital anomalies or miscarriage; data on higher doses, long durations, late third-trimester use, and lactation are limited—use under clinician guidance.

Commonly used ranges in studies (forms vary; standardizations often to gingerols/shogaols):

• Nausea/vomiting in pregnancy: 500–1000 mg/day of ginger powder/extract in divided doses for up to 3–4 weeks.
• Postoperative nausea: 1–2 g single dose 30–60 minutes before anesthesia.
• Chemotherapy-induced nausea: 0.5–2 g/day alongside standard antiemetics for several days around chemotherapy cycles.
• Dyspepsia/gastric motility: 1–1.5 g/day, often before meals, for 2–4 weeks in small trials.
• Osteoarthritis: 500–1500 mg/day of standardized extract in divided doses for 4–12 weeks.
• Primary dysmenorrhea: 750–2000 mg/day during first 3 days of menses in divided doses. Culinary equivalents used traditionally: ~2–5 g/day dried ginger (or ~10–20 g fresh). Optimal dosing depends on individual factors and the condition treated; product standardization varies.

• Known allergy to ginger or other Zingiberaceae plants.
• Bleeding disorders (e.g., hemophilia, severe thrombocytopenia) or active bleeding.
• Concurrent use of anticoagulants/antiplatelets or upcoming surgery/procedures with bleeding risk (stop supplemental ginger at least 1–2 weeks prior unless advised otherwise).
• Symptomatic GERD, esophagitis, or peptic ulcer disease (may worsen reflux/irritation).
• Gallstones or biliary obstruction (may stimulate bile flow; risk of colic).
• Diabetes on glucose-lowering therapy (monitor for hypoglycemia).
• Hypotension or on antihypertensives (monitor for additive BP lowering).
• Pregnancy: avoid high-dose supplements; use low-dose, short-term only with obstetric guidance. Lactation: insufficient safety data for supplemental doses—prefer culinary amounts.