Choosing a UVB filter can become a gamble, and the stress is understandable. You may be looking for a high SPF, a good skin feel, and stability of your formula. On top of this, there are ever-changing regulations to keep in mind. Below is a brief, jargon-free overview of the differences between ethylhexyl triazone and octyl methoxycinnamate.
We will discuss their properties, application tips, and limitations. By the end of this post, you will know which UVB filter is better for your formula.
What Do These Two UVB Filters Do?
To start with, here is basic information about both filters. EHT is an oil-soluble filter peaking at 314 nm. OMC is another name for octyl methoxycinnamate. On a label, you can find ethylhexyl methoxycinnamate or octinoxate (OMC). It is a UV filter peaking at 310 nm. Both filters block UVB rays causing sunburns. Neither of them provides actual UVA coverage, so you will have to use a UVA filter in addition to these two.
Which Filter Provides Higher SPF per Percent?
As a rule, EHT is more efficient per percent. It absorbs UVB intensely, so a little of the filter goes a long way. Thus, a higher SPF can be achieved using less filter. OMC is less efficient per gram, but it usually is cheaper, but need to add with higher dosage to achieve the desired SPF...
Which One Remains Stable in Sunlight?
This is where these filters differ. Ethylhexyl triazone is photostable, so its activity remains high in the sunlight. OMC is photodegradable. Under UV irradiation, it transforms into a cis-isomer with lower absorbance. Also, it can affect avobenzone, a UVA filter, decreasing its efficiency.
Which One Is Easier to Formulate?
In this regard, OMC is much easier. Being a liquid, it mixes easily with other ingredients. It can help dissolve some other filters used in your formula. EHT is a white powder requiring polar emollients to remain soluble. Otherwise, crystallisation may occur at low temperatures.
However, it can be used in water-resistant sunscreens successfully. Nonetheless, it should be tested in your final formula.
What Do the Rules Say?
Now let's move to regulatory aspects. According to Annex VI of Regulation (EC) No 1223/2009 in the EU, a maximum concentration for EHT is 5% and 10% for OMC. In the US, according to the OTC monograph, octinoxate (OMC) is allowed up to 7.5%. However, EHT is not included in the monograph and cannot be used in US OTC sunscreens at the moment.
Besides, since 2021, Hawaii has banned the sale of sunscreens containing octinoxate. The review of UV filters by regulatory authorities continues, so avoid such claims as "reef-safe" or "worldwide approved". Instead, look at the latest rules in markets where you want to sell your formula.
Which One Should You Pick?
Choose EHT if you are interested in a high SPF and photostability of your formula and if it is allowed in the market you address.
Otherwise, go with OMC if cost and processability are your priorities. However, some companies combine both filters with others.
Conclusion
Neither filter wins all the time. It all depends on your priorities, budget, and market. Therefore, pay attention to all aspects mentioned above when choosing a filter.
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