Guide
Hyssop and medications: what to check
No confirmed drug interaction exists for hyssop. The one human trial excluded people taking theophylline, and an animal study found a sedative effect worth flagging for anyone on a sedating medication.
No study has tested hyssop directly against a prescription medication, so there's no confirmed drug interaction to report. What exists is a short list of medications the one human trial deliberately excluded, and one animal finding on sedation — both reasons for caution rather than proof of an interaction.
Theophylline and asthma medication
The one human trial of an oral hyssop extract excluded anyone taking theophylline, an asthma medication, from participating. The published trial doesn't explain the exact reason, but it means there's no data on combining hyssop with theophylline or, by extension, other prescription asthma medication. If you take a prescription medication for asthma or another respiratory condition, ask a doctor before adding hyssop alongside it.
Sedatives and other CNS depressants
A phytochemistry review reported that hyssop extract had a sedative effect in agitated mice. No human trial has tested whether hyssop adds to the drowsiness of a sedative, sleep medication or alcohol, so this isn't an established interaction — but the animal finding is a reasonable basis for caution. Ask a doctor before combining hyssop with a sedating medication.
Anti-seizure medication
Hyssop essential oil, taken internally, concentrates a compound identified as a seizure trigger. If you take medication for seizures or epilepsy, that's a reason to avoid hyssop essential oil specifically and to ask a doctor before using hyssop in any other form.
What isn't known
No research has tested hyssop against blood thinners, diabetes medication, or any other prescription drug beyond the two named above. That's a gap in what's been studied, not a clean bill of health — if you take a prescription medication of any kind, ask a doctor before adding hyssop.
Questions people ask
Does hyssop affect thyroid medication?
No research has tested hyssop against thyroid medication, or reported an effect on thyroid function at all. There's nothing to say either way, which is itself a reason to ask a doctor before combining the two.
Related reading: who should not take hyssop, hyssop side effects, and how much hyssop should you take a day?.
Sources
- Effect of Hyssop (Hyssopus officinalis) Syrup on Mild to Moderate Asthma: A Randomized Double-Blind Placebo-Controlled Trial A 2024 randomized trial found hyssop syrup improved lung-function and symptom measures in asthma patients with a productive cough, but worsened them in patients with a dry cough, over 4 weeks added to usual treatment.
- Hyssopus Essential Oil: An Update of Its Phytochemistry, Biological Activities, and Safety Profile A phytochemistry review found hyssop's essential oil is dominated by pinocamphone and isopinocamphone, called the plant relatively safe at food-use levels, but said more safety research is needed.
- The Effects of Various Essential Oils on Epilepsy and Acute Seizure: A Systematic Review A 2019 systematic review named hyssop, alongside several other essential oils, as able to trigger seizures when taken internally, due to convulsant compounds including pinocamphone.
*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.