Can you use essential oils in a plastic diffuser? What kind of plastic is safe?

Can Essential Oils Be Used in Plastic Diffusers?

Hey, I've been using diffusers and essential oils for years and have encountered some minor issues, so I’m sharing my experience. Simply put, essential oils shouldn’t be used in just any plastic diffuser. Since essential oils are concentrated plant extracts, certain components like limonene or pinene can gradually corrode or dissolve certain plastics. This may cause the device to warp, leak oil, or even release harmful substances into the air. Not trying to scare you—I personally tried a cheap plastic diffuser with citrus oil, and its base softened with a weird smell shortly after.

But it’s not entirely off-limits—it depends on the plastic type. If your diffuser is plastic, first check the manual or bottom label (usually marked with a number or letter code). Not all plastics react poorly to oils.

Which Plastics Are Safer?

Based on my experience and research, these plastics are relatively oil-resistant and suitable for essential oil diffusers:

PP (Polypropylene, Code #5): This is the most common type. Several of my water bottles and containers are PP, and they handle oils fine. It resists chemical corrosion and won’t dissolve easily. Many mid-to-high-end diffusers use this.
HDPE (High-Density Polyethylene, Code #2): Also quite durable. I’ve stored essential oils in HDPE bottles for years without issues. Ideal for ultrasonic diffusers that require water.
PET (Polyethylene Terephthalate, Code #1): Often used in drink bottles. It has moderate oil resistance, but avoid highly concentrated oils or prolonged use. I’ve tested it short-term without problems.

Avoid plastics like PS (Polystyrene, Code #6) or cheap PVC (Polyvinyl Chloride, Code #3)—they degrade quickly with oils and will ruin your device.

My Tips

Opt for glass or ceramic diffusers if possible—they handle oils effortlessly.
For plastic diffusers: Dilute oils (e.g., with water or carrier oil)—never use them undiluted. Clean thoroughly after each use to avoid residue.
When buying new: Choose devices labeled "essential-oil compatible" or made with the safer plastics above. Check online reviews to avoid pitfalls.
Safety first: If unsure about the plastic type, don’t risk it. I now prioritize non-plastic options—much less hassle.

In short, plastic isn’t an absolute no-go, but choosing the right type is crucial. Hope this helps—feel free to ask more!