Chamomile

• Anxiolytic / GABAergic effects (apigenin): Chamomile contains the flavonoid apigenin, which has been shown in preclinical work to interact with GABA-A / benzodiazepine receptor sites and modulate GABAergic signalling — a plausible biological mechanism for calming/anxiolytic and sedative effects. These pharmacologic and animal/in-vitro data are summarized in review and experimental papers. MDPI
• Anti-inflammatory / neurotrophic effects: Apigenin and other chamomile constituents show anti-inflammatory effects (reducing TNF-α, IL-6 in animal models) and influence molecules (BDNF, CREB) linked to sleep and mood regulation; these pathways are relevant because inflammation and neurotrophic signalling can affect stress, anxiety and sleep. Frontiers
• Sleep improvement and calming ritual: Chamomile tea/aromatherapy may improve sleep quality and reduce sleep fragmentation in some studies — improving sleep can indirectly reduce PTSD symptom burden (hyperarousal, intrusive thoughts). Systematic reviews / clinical summaries note chamomile’s benefit for sleep and anxiety symptoms. EatingWell

Important limitation: Most clinical evidence tests chamomile for generalized anxiety disorder (GAD) or sleep problems — not PTSD specifically. Evidence that benefits for GAD/sleep translate to robust improvements in PTSD core symptoms (re-experiencing, avoidance, hypervigilance) is limited or absent. Use that as the context for considering chamomile as an adjunct rather than a stand-alone, PTSD-targeted therapy. CNR Clinical Nutrition Research

Forms used in clinical research

• Oral standardized extract (capsules): The best-controlled clinical trials used pharmaceutical-grade chamomile extract in capsules. Doses in trials ranged from ~220 mg up to 1,500 mg/day depending on the study and phase. For example, one long-term study used 1,500 mg/day as 500 mg three times daily during an open-label phase. Another earlier trial used up to ~1,100 mg/day in a dose-escalation design. Materia Medica
• Tea (infusion): Many people use chamomile as a tea. Clinical-grade data on exact cup-for-cup equivalence to extracts is inconsistent, but common consumer guidance is 1–4 cups daily, brewed by steeping a tea bag or 1–2 teaspoons of dried flowers in hot water for 5–10 minutes. Trials testing tea specifically are fewer and less standardized than extract trials. WebMD
• Aromatherapy / essential oil / topical: Some small studies and preclinical work examine inhalation or topical use (essential oil) for relaxation/sleep; evidence is more limited and variable than for oral extracts. Pharmacognosy Journal

How dosing looked in the best evidence

• Acute/short RCT (Amsterdam 2009): randomized, double-blind, placebo-controlled trial in mild–moderate GAD — participants took chamomile extract (dose escalation up to about 1,100 mg/day in that trial) for 8 weeks and showed a modest but statistically significant reduction in anxiety vs placebo. See study for details on escalation and timing. Materia Medica
• Longer trial (Phytomedicine 2016 — Mao et al.): two-phase design: open-label 12-week chamomile extract 1,500 mg/day (500 mg three times daily) for responders, then randomized continuation vs placebo for 26 weeks to study relapse prevention. This is the trial that gave the clearest data on longer-term extract dosing and tolerability. ICHGCP

Practical/consumer-level instructions (summary)

• If using tea: steep 1–2 teaspoons (or one tea bag) in hot water 5–10 minutes; drink 1–4 cups/day depending on tolerance and effect. WebMD
• If considering extract capsules (the form used in RCTs): trial doses in research ranged ~220–1,500 mg/day, with many studies using 500 mg three times daily (1,500 mg/day) in the open-label phases or lower doses in other trials. Do not start high-dose extracts without medical advice, particularly if you take prescription medications or have medical conditions. Materia Medica

1. Amsterdam JD et al., 2009 — Journal of Clinical Psychopharmacology

• Design: Randomized, double-blind, placebo-controlled trial of oral Matricaria recutita (chamomile) extract in mild–moderate generalized anxiety disorder (GAD).
• Dose & duration: dose escalation up to ~1,100 mg/day, 8 weeks.
• Result: modest but statistically significant reduction in HAM-A anxiety scores vs placebo (p≈0.047). Tolerability similar to placebo. (First controlled clinical trial showing modest anxiolytic effect.) Materia Medica

1. Mao JJ et al., 2016 — Phytomedicine (Long-term chamomile trial)

• Design: Two-phase study: 12-week open-label chamomile extract (responders), then responders randomized to 26 weeks continuation chamomile vs placebo (relapse prevention).
• Dose: 1,500 mg/day (500 mg three times daily) during open-label.
• Result: Chamomile was generally safe and reduced GAD symptom scores; continuation therapy did not significantly reduce relapse rate in this trial’s sample but showed symptom reductions and was well tolerated — authors call for larger trials. Europe PMC

1. Systematic reviews / narrative reviews (recent)

• Reviews summarizing clinical and preclinical literature conclude chamomile shows evidence for modest anxiolytic and sleep-supporting effects, but results across studies are inconsistent and more high-quality, larger trials are needed. (Summaries and reviews in Clinical Nutrition Research, Phytomedicine, and other journals.) CNR Clinical Nutrition Research+1

1. Mechanistic/preclinical studies on apigenin

• Multiple lab and animal studies show apigenin (a key chamomile flavonoid) interacts with GABAergic systems and produces sedative/anxiolytic effects in models — these are mechanistic supports, not clinical proof for PTSD. ScienceDirect

Crucial point: none of these are randomized trials in PTSD populations specifically. The clinical evidence supports anxiolytic and sleep-improving effects (useful for PTSD comorbidities), but direct evidence for chamomile as a PTSD treatment is currently lacking. CNR Clinical Nutrition Research