--- title: Does menstrual cycle phase affect anxiety response to CO2 in women with panic disorder? description: Yes. Women with panic disorder showed significantly stronger anxiety during the early follicular phase than the luteal phase after breathing a CO2 mixture. Co url: https://niyora.com/research/papers/menstrual-cycle-related-sensitivity-to-35-co2-in-panic-patients-1995/ --- - [Niyora](https://niyora.com/) - [Research](https://niyora.com/research/) - [Library](https://niyora.com/research/library/) - Does menstrual cycle phase affect anxiety response to CO2 in women with panic disorder? Randomised trial, 1995 # Does menstrual cycle phase affect anxiety response to CO2 in women with panic disorder? Yes. Women with panic disorder showed significantly stronger anxiety during the early follicular phase than the luteal phase after breathing a CO2 mixture. Controls showed no anxiety response. Early or limited evidence 10 women with panic disorder and 7 control women ## What they did In a double-blind crossover study, 10 women with panic disorder and 7 control women breathed a mixture of 35% carbon dioxide and 65% oxygen during two phases of their menstrual cycle: early-follicular and midluteal. Anxiety was measured after the inhalation. ## What they found In women with panic disorder, anxiety after CO2 inhalation was significantly stronger during the early-follicular phase than the midluteal phase. Control women had no anxiety reactions to the CO2 at either phase. ## What it means for you Menstrual cycle hormones may increase how sensitive women with panic disorder are to CO2, triggering stronger anxiety. This suggests panic symptoms might worsen during the early follicular phase of the cycle. The main limits are the very small sample and that breathing CO2 in a lab may not reflect real-world panic attacks. 10 Women with panic disorder 7 Control women 35% CO2 concentration ## About the study Original title Menstrual cycle-related sensitivity to 35% CO2 in panic patients Authors Perna G, Brambilla F, Arancio C et al. Journal Biological psychiatry Year 1995 Study design Randomised trial Participants 10 What was tested Inhalation of 35% CO2 and 65% oxygen Read the paper [doi.org/10.1016/0006-3223(94)00154-u](https://doi.org/10.1016/0006-3223(94)00154-u) ## Topics [Menstrual cycle and mood](https://niyora.com/research/topics/condition-cycle-mood/)[Anxiety and tension](https://niyora.com/research/topics/symptom-anxiety/)[Anxiety disorders and OCD](https://niyora.com/research/topics/comorbidity-anxiety-disorders/) Research tells you what helps on average. Niyora helps on the day it hits. Calm down, see it another way, and decide what to say, with a PMS and PMDD app built by a doctor. ## Related studies Systematic review, 2022 Do mental health disorders get worse during the menstrual cycle? Cohort study, 1993 How common are premenstrual and menstrual symptoms in women? Study, 2026 Do anxiety and depression get worse before your period if you already have a mental health condition? Study, 2026 What are premenstrual syndrome and premenstrual dysphoric disorder? Systematic review, 2022 Do anxiety disorders, PTSD and OCD get worse at certain points in the menstrual cycle? Case-control study, 2021 Does sleep quality change across the menstrual cycle in women with anxiety disorders? Ask AI about this page Copy prompt ChatGPT ↗ Claude ↗ Perplexity ↗ Google AI Mode ↗ Grok ↗