Rosemary oil: does it work?

Why everyone is talking about it

Rosemary oil went viral on social media with a simple message: "it works as well as minoxidil, without the side effects." Videos of people massaging oil into their scalps are everywhere. Almost every one of them points, directly or indirectly, to the same study.

That makes rosemary oil a useful example of how one small trial can turn into a "fact" online. So let's look at what the trial actually did.

The one trial

In 2015, researchers randomly divided 100 people with pattern hair loss into two groups of 50.¹ One group used rosemary oil on the scalp; the other used minoxidil 2%. They were followed for six months, with checks at three and six months.

What they found:

• At three months, hair counts had not changed in either group.
• At six months, hair counts had risen in both groups, and the difference between the groups was not statistically significant.
• Scalp itching increased in both groups, and was more common with minoxidil.

On the surface, that sounds like good news for rosemary. Now the fine print.

What the trial can and cannot tell you

It compared rosemary with the weaker minoxidil. In men, the 5% strength gave about 45% more regrowth than 2% in a large trial.³ Being "no worse than 2%" is not the same as being as good as the treatment most men use today.

"No significant difference" is not "the same". With 50 people per group, a trial can easily miss a real difference. It was not designed to prove that the two were equal.

There was no placebo group. Without a group that used a plain oil or nothing at all, we cannot tell how much of the gain in either group came from the treatment, and how much from other things, such as people taking better care of their scalp because they were in a study.

It has not been repeated. One small trial is a reason to do a bigger one, not a conclusion. As of our last review, no larger trial has confirmed it.

The details matter. The trial used a specific product and routine. A few drops of an essential oil from a shop, or a "rosemary water" spray, may not be the same thing.

Should you try it?

If you have pattern hair loss and want the best chance of keeping your hair, start with the treatments that have strong evidence: minoxidil and, for men, finasteride. The European guideline recommends both.²

Rosemary oil may make sense if you cannot use minoxidil, have decided against medicines, and accept that the evidence is weak. It is unlikely to do harm if you use it carefully. Just do not let it delay a treatment that works, because pattern hair loss is easier to slow than to reverse.

If you try it, do it safely

Pure essential oils are strong and can irritate or sensitise the skin.

1. Dilute it. Mix a few drops of rosemary essential oil into a tablespoon of a carrier oil, such as jojoba or almond oil. Never put undiluted essential oil on your scalp.
2. Do a patch test. Put a little of the mix on the inside of your forearm and wait 48 hours. If you get redness, itching or a rash, don't use it.
3. Apply to the scalp, massage it in gently, and wash it out after a few hours or the next morning.
4. Keep it away from your eyes, and wash your hands after use.
5. Be consistent and patient. In the trial, nothing changed at three months. Judge it at six, with progress photos.

Do not use rosemary oil on broken, sunburnt or inflamed skin. Ask a doctor or pharmacist first if you are pregnant or breastfeeding, have epilepsy, or have sensitive skin or allergies.

If you use minoxidil too, do not mix them. Apply minoxidil to a clean, dry scalp, and use any oil at a different time of day, so the oil does not stop the minoxidil from getting into the skin.