Good question, George.
I did some research and found one published study on Oil of Oregano and blood pressure.

Researchers found 100 mcg/kg. of carvacrol caused a decrease in heart rate, mean arterial pressure, and diastolic and systolic pressures in anesthetized rats.

The study didn't indicate how much the pressures decreased. Of course rats are different than humans. But if we convert this to humans, this dosage is equivalent to a 70 kg. person taking almost 7 grams of carvacrol.

How much carvacrol do you get in the average Oil of Oregano dosage? Depending on the brand of oregano oil, 4 drops of oil will yield about 13 mg. of carvacrol and a 150 mg. softgel may contain up to 7 mg. of carvacrol.

Researchers found no effects on blood pressure at dosages of 1, 10 and 20 mcg/kg in animal studies.
It appears that taking excessively high dosages of Oil of Oregano may cause a decrease in blood pressures, but there are no documented human studies to prove this.

To be safe, consult you healthcare provider when using any nutritional supplement and don't exceed the recommended dosages suggested by the manufacturer.

I am not a scientist, and I am new to using herbal remedies, but I have high blood pressure that is currently controlled with medication. I started taking Oil of Oregano a week ago, and my first dosage sent my BP through the roof. I had a screaming headache for almost two days. However, I continued using the O of O, and there are no signs of side effects now. I no longer get any headaches, and actually, I feel great! It has been one week now. I do think there is something there that can affect folks with hypertensive tendencies initially, but from my own experience, it seems to go away after a couple of days.

Again, I'm no scientist. Just my own .02 cents. Good luck!

Thanks for sharing your experiences with us. Can you tell us what brand of Oil of Oregano you were using and the dosage taken? It's interesting that Oregano Oil initially caused an increase in your blood pressure and then it regulated itself. I'm sure other readers would be interested to know if this was dependent on the dosage taken or if others could expect this possible side effect.

Kevin L.

I was using a local store brand with a minimum of 70% (or 30mg) per 43 mg of Oil of Oregano. I was taking 4 drops about 3 times per day, diluted in water or tea or juice.

Like I said, it cleared up after the initial two days, and has not come back and I still take it daily.

I used North American brand and it shot my pressure to 144/103. The bottom number scared me. The first day was one drop, it cleared a post nasal drip for me. The second day I took about 5 to 7 drops spread out over the day. The third and fourth day about 5 drops spread out. The third and fourth day are when the blood pressure rose significantly. I usually read 122/80 to 135/90. I immediately stopped taking it and my pressure is back down but the 'ball' in my throat where nasal drip accumulates is back!

It was wise to discontinue taking Oil of Oregano once you started experiencing high blood pressure. It looks like the higher dosage of 5 drops per day was too much for you - but you did say the initial one drop per day cleared your post nasal drip?

I guess too much of a good thing can have the opposite effects we're looking for. This could apply to using too much Oil of Oregano.

I recently purchased some oil of oregano at my local health food store. Yesterday I started myself on three drops in a glass of water. I repeated the dose again today and began to feel my nose getting stuffy and a slight headache... I took my blood pressure reading and it was 160 over 90. I do have high normal readings anyhow but this makes me feel afraid to use it again.

Since using the oil of oregano 3 years ago, I cleared my sinus problems for good. Each time I feel like the sinus problem is coming on I just take a drop of two and within one hour I feel better and it goes away. I had sinus problems for the past 10 years, shots, pills could not help me, but I found out about the oil from neighbor and it's a magical potion.

I have been using 2 drops of Oreganol brand Oil of Oregano twice a day for sinusitis for 4 days. I have borderline high blood pressure and today it was 168 over 95. Way too high. Would using a whole herb product of the wild oregano work better for me?

Reply: You could be right about the Oreganol brand of Oil of Oregano being too concentrated. The Oreganol P73 is apparently rated to contain at least 62% carvacrol. I would be concerned about taking any product that may cause an unwanted rise in blood pressure. Perhaps you may have to resort to a lower concentration to avoid the rise in blood pressure or discontinue using it.

I've been taking Oil of Oregano for two days and checked my blood pressure today...it was 160/104...my b/p was 104/80 3 days before beginning the Oil of Oregano. I started taking it for my toenail fungus but now will use the oil directly on my nail rather than to ingest it.

I have been taking oil of oregano for about 3 weeks and have been increasing my dosages. the oil is 100%. I took 7 drops this morning and then my heart started to flutter. Its really scary. I took my blood pressure and it is 146/106 and pulse 92. That is not good. I am not sure if it is the oil or oregano or not. I was actually researching whether the oil of oregano can lower my blood pressure and i ended up on this sight about how it could possibly raise my blood pressure.

I began taking Oil of Oregano about 2 weeks ago. I began taking one capsule a day, and then moved to 2 per day. That dosage increase gave me a raging headache for 2.5 days. I literally wanted to cut my head off! But, I stuck through it because I knew it was probably working and killing off whatever I had in me. The headache eased off eventually, and (I know this sounds cliche) now I'm waking up bright and early every morning (I used to wake up late all the time and still feel drained), I'm not sleepy during the day, I'm actually less hungry, and I'm losing weight during the day by eating healthier and cutting out bread and sugars. I highly recommend oil of oregano to anyone feeling fatigued, lethargic, or anyone experiencing candida/parasite symptoms...

I started taking oregano oil about a month ago. I started with just 1 drop a day and increased slowly to 4 a day. Although candida seems to be more under control, there were new problems appearing. Since I am also in a new diet I did not link the strange feeling in my heart to the oregano oil. I kept on having it.

This last week it has been worst, my heart beats flutter most of the time, it feels like bubbly palpitations and I feel weak. then the feeling goes away and I am fine, only to come back again.
Today I woke up with my right eye all red with an obvious broken blood vessel and I got scared.
I have not taken my blood pressure as only now reading your site I suspect this could be the problem. I normally have somehow low blood pressure. I have stopped taking the oregano oil. I hope it all comes back to normal soon...

I've been taking 1500 mg of oil of oregano, two per day at the same time total 3000mg. My blood pressure is 122/ 65 and heart rate 53 bpm. I take about 30 supplements a day; If you're experiencing any of the symptoms described by others, trust me, it's not the Oil of Oregano. Go see a doctor because oregano is not going to make your heart flutter or raise your blood pressure. It increases blood flow and kills fungus so if anything it will lower your blood pressure, not raise it. I also take 2 blood pressure medications a day; it used to be 190 over 113. Since then I turned into a health nut and a pro-active person. Hope this has been helpful.

Blood pressure up to 137/87 - mine is usually a little low and I am on meds. I just started taking oil of oregano because of the time of year and colds. Really does the job on that. But noticed my blood pressure up so high. So I started to look into supplements and the first one being oil of oregano. After seeing what people have been saying I might just lay off it for a few days to see what happens. It worries me that it's so much higher.

Many years ago I was prescribed Oil of Oregano by a Naturopath to clear up the candida in my blood. I was younger and not experiencing HBP. However now at age 56, I was experiencing foggy head, fatigue and body aches so I suspected candida again. I started taking Oreganol about 2 - 3 drops per day in the morning in water with lemon juice. I am on blood pressure pills and water pills (low doses of both) for hypertension. All of a sudden, my blood pressure was 163/100 and that was with the BP medications. I was also experiencing palpitations. This is scary and I guess I should stop because I'm awaiting surgery on my shoulder and HBP would cause them to postpone the surgery. Too bad - it was making my body feel less fatigued.