On Guard is a doTERRA essential oil blend made from wild orange peel, clove bud, cinnamon bark, eucalyptus leaf, and rosemary leaf. People typically use it during cold season by diffusing it, applying it topically with a carrier oil, or adding it to steam inhalations. While no essential oil is a proven cold remedy, there are reasonable ways to use this blend for comfort and symptom relief.
What On Guard Actually Contains
The blend combines five oils that each bring something different. Wild orange contributes a bright citrus scent. Clove and cinnamon are the “hot” oils in the mix, responsible for both the warming sensation and the skin sensitivity risks. Eucalyptus is the ingredient most associated with respiratory relief, as it produces that familiar cooling, mentholated feeling when inhaled. Rosemary rounds out the blend with a camphor-like quality.
A lab study published in BMC Complementary and Alternative Medicine tested On Guard against influenza virus in cell cultures and found it reduced the number of new viral particles by up to 90% at certain concentrations. That’s a notable result, but it happened in a petri dish, not inside a human body. Cell culture findings don’t translate directly to drinking tea with essential oil drops or rubbing it on your chest. They suggest the blend has antimicrobial properties worth studying further, but they don’t prove it will shorten your cold.
Diffusing for Congestion Relief
The most common and lowest-risk way to use On Guard during a cold is in a diffuser. Add three to four drops to a standard ultrasonic diffuser with water and run it in the room where you’re resting. The eucalyptus and rosemary components create a vapor that can help open your nasal passages temporarily, similar to how a menthol rub works.
Run the diffuser in 30- to 60-minute intervals rather than continuously, especially in smaller rooms. If you have pets, keep the door open so they can leave the room. Cats in particular are sensitive to essential oil vapors, and clove and eucalyptus can be irritating to them.
Steam Inhalation
For more targeted congestion relief, add one to two drops of On Guard to a bowl of hot (not boiling) water. Drape a towel over your head, close your eyes, and breathe in the steam for five to ten minutes. This concentrates the vapor directly in your airways and can loosen mucus more effectively than a diffuser alone. Keep your face at least 12 inches from the water’s surface to avoid burning yourself, and keep your eyes closed throughout since the cinnamon and clove components can irritate them.
Applying It to Your Skin
On Guard contains two “hot” oils, clove and cinnamon, that can cause real skin reactions. Clove oil has been shown to be cytotoxic to skin cells at concentrations as low as 0.03%, and the eugenol it contains can trigger hypersensitivity reactions at very small amounts. This means you should never apply On Guard directly to your skin without diluting it first.
Mix one to two drops of On Guard with about a teaspoon of carrier oil like fractionated coconut oil, jojoba oil, or sweet almond oil. Common places to apply it during a cold:
- Bottoms of the feet: The skin here is thicker and less likely to react. Some people apply it to the soles before putting on socks at bedtime.
- Chest: Rub the diluted blend across your upper chest for a warming sensation similar to a vapor rub. The eucalyptus and rosemary vapors rise toward your nose as you breathe.
- Along the spine or back of the neck: Another area where the warming effect can feel soothing when you’re achy from a cold.
Before applying it anywhere, do a patch test on a small area of your inner forearm. Wait 30 minutes. If you see redness, feel burning, or develop a rash, wash the area with soap and water and stick to diffusing instead. Children have thinner, more reactive skin, so use extra caution with topical application on kids and increase the carrier oil ratio significantly.
Adding It to a Bath
A warm bath with On Guard can combine the steam inhalation benefit with topical application. The key detail: essential oils don’t dissolve in water on their own. They float on the surface and can contact your skin undiluted. Mix two to three drops of On Guard into a tablespoon of carrier oil or a cup of Epsom salts first, then add that mixture to the bath. This disperses the oil more evenly and prevents concentrated contact with sensitive skin.
A Note on Swallowing Essential Oils
Some of the individual oils in On Guard, including sweet orange, cinnamon, and rosemary, are classified as Generally Recognized as Safe for use in food by the FDA. However, clove and eucalyptus are not on that same list. Internal use of essential oils is controversial even among aromatherapists, and the concentrated nature of essential oils means they can irritate your esophagus, stomach lining, and mucous membranes. If you’re considering putting drops in water or a capsule, know that this carries more risk than inhalation or diluted topical use.
What On Guard Won’t Do
No essential oil cures a cold. The common cold is caused by viruses that run their course in 7 to 10 days regardless of what you inhale or rub on your skin. What On Guard can realistically offer is temporary congestion relief from the eucalyptus and rosemary vapors, a warming comfort from the clove and cinnamon, and a pleasant scent that makes resting feel a bit less miserable. Those are genuinely useful things when you’re sick. They’re just not the same as treatment.
Pair it with the basics that actually help your body recover: staying hydrated, sleeping as much as possible, and using saline nasal spray or a humidifier to keep your airways moist.