Hydrosols are water-based products made from the distillation of fresh flowers, leaves, fruits, and other plant materials. Some claim they have health benefits, but there is limited scientific evidence to support this.

Hydrosols are a byproduct of the essential oil manufacturing process and share many of the same properties as essential oils.

The difference is that hydrosols are mostly water. This means they’re much less concentrated than essential oils. They also have a softer, more subtle scent.

Hydrosols are often used in skin care or aromatherapy products. While they’ve also been used for medicinal purposes, more research is needed to demonstrate their effectiveness.

Keep reading to learn about how hydrosols are used and their purported benefits.

Hydrosol products should be used with caution, since they’re not regulated by any governing body and there’s a lack of scientific research about their safety and effectiveness.

Hydrosols are water-based products made from the distillation — by water or steam — of plant matter such as flowers, bark, roots, and leaves. The distilling process produces two end products:

  • Essential oil: the oil-soluble parts of the plant
  • Hydrosol: the water-soluble parts of the plant (this liquid also contains microscopic drops of essential oil)

Essential oils and hydrosols have some similar properties, but hydrosols have a much higher water content.

They also have a more subtle scent than their essential oil counterparts and may be gentler on your skin.

Manufacturers may add hydrosols to a variety of products, including:

There’s a lack of scientific research on the benefits of hydrosols. But anecdotal evidence suggests that certain plants converted into hydrosols may be useful in several ways.

For example, here are some plants and a few of their supposed benefits:

  • Lavender: relaxation
  • Rose: astringent, perfume
  • Lemon balm: stress relief
  • Witch hazel: skin cleanser
  • Chamomile: anti-inflammatory

Some hydrosols contain carboxylic acids, which may explain why proponents of hydrosols believe it has anti-inflammatory properties.

One older 2008 study suggested that rose hydrosols may help people with insomnia. However, it’s important to note that the most effective rose hydrosol in the study contained more essential oil than the other hydrosols examined.

More research is needed to support the effectiveness of hydrosols.

In the Middle East, people use hydrosols sweetened with sugar or honey as nutritive waters. There are more than 50 kinds of these hydrosols available in Iran, but they’re not available elsewhere in the world.

Manufacturers may also use hydrosols in products not intended for oral consumption. These include:

  • skin and makeup products, like toners, creams, and other emollients
  • topical creams for wounds, inflammation, or soothing the skin
  • body products like perfume
  • aromatherapy products that can be diffused into the air

There are many hydrosol products available commercially.

Consider the manufacturer along with any added ingredients before purchasing and using hydrosol products. Fragrances and dyes may irritate your skin if you apply the product topically. Diffusers may also cause respiratory problems.

There’s not a substantial amount of evidence regarding the safety of hydrosols in the United States. As with essential oils, the Food and Drug Administration (FDA) does not regulate hydrosols. So it’s advisable to use them at your own risk.

One 2018 study claims that hydrosols, unlike typical essential oils, are safe to drink. The authors attribute this to their lack of strong aromas, which reduces the risk of adverse reactions like headaches or contact dermatitis. They also claim that people can apply hydrosols directly to the skin.

Indeed, a 2023 study investigating the effects of hydrosols on skin cells concluded that the following hydrosols are safe for long-term skin use at a 2.5% concentration:

A hydrosol concentration of 10% or above, meanwhile, may be harmful to your skin — especially with lavender, lavandin, and rosemary.

However, it’s worth noting that these findings may not apply to all hydrosols or to different concentrations beyond the tested dilutions. The study also fails to consider how the studied hydrosols may interact with other cosmetic ingredients.

Overall, there’s a scant amount of research on hydrosols and their safety, and the available research has limitations.

In the United States, using aromatherapy and other types of plant-based medicines is considered a complementary or alternative therapy. This means they are treatment methods outside of conventional medicine.

Complementary medicine involves using these products alongside medications or therapies that your doctor prescribes. Alternative medicine involves using these products in place of conventional medication.

These therapies lack definitive research. That’s why they’re not considered evidence-based treatments.

You should talk with a doctor before ingesting these products. Discuss how these treatments might interact with other medications you take. Stop using them if you have a reaction.

Hydrosols can be made intentionally or as a byproduct in the essential oil distillation process.

Look for products intentionally made as hydrosols. These may be of higher quality. Manufacturers of specific hydrosol products versus those packaging the byproduct may put more care and attention into the product they produce.

Hydrosols should be packaged in bottles similar to essential oils. Dark bottles prevent light from altering the product. Also, avoid overheating hydrosol products.

Manufacturers create hydrosols with steam, water, or a combination of both. In some distillation techniques, herbs sit above heated water.

Equipment captures the steam, moves the vapor into equipment that can condense it, and then extracts it as hydrosols.

You can make hydrosols at home along with essential oils. Here’s what you’ll need:

  • 2 heatproof bowls (a large one and a small one)
  • 1 large pot
  • several cups of the plant you intend to distill (don’t just think of flowers when gathering plants; you may also use other parts of the plant)
  • ice
  • water

Instructions

  1. Place the large bowl upside down in the pot, with the small bowl resting right-side up on top.
  2. Place the plant parts in the pot but not in the bowl, and then cover the plants with water.
  3. Place the lid on the pot and add ice on top of the lid. It may be easier to turn the lid upside down to rest the ice on top of it.
  4. Turn on your burner. Once the water boils, reduce the heat on the burner so the water simmers. Simmer for 30 minutes. Use with caution to avoid burns.
  5. Replace melted ice on the pot’s lid as needed. At the end of this steaming process, open the pot of the lid. The hydrosol will be in your small bowl. Oils floating on top of the water are essential oils; you can skim these off the water if you desire.
  6. Store homemade hydrosols in the refrigerator or another cool place, preferably in dark containers.

Hydrosols are water-based products made from plants. Some people believe they have health benefits, like stress relief, or can be used as part of a skin care routine.

However, it’s best to use hydrosols with caution. There’s little scientific evidence of their safety or effectiveness, and they’re not regulated by the FDA.