I’m a creature of habit, especially when it comes to skincare. Once I’ve found a cleanser that doesn’t irritate me or a serum that clears up my breakouts, I’m committed for the long haul. However, I noticed that my trusted serum wasn’t quite cutting it suddenly. It used to be a guaranteed glow-giver and now my skin just appeared a bit… meh.

Like when relationships go stale, I wondered if it was me and tried to analyse what had gone wrong. Had I been mixing it with other ingredients that had effected its potency? Had it been open too long? Had my skin become immune to it? I couldn’t seem to come up with an answer. 

Then I came across the term tachyphylaxis (don’t worry, I can’t pronounce it either) which could be the reason for my dwindling skincare results. “Tachyphylaxis (a medical term for a once successful treatment that becomes less effective over time) can occur in some areas of skincare, but it’s not always a straightforward case of the skin ‘getting used’ to a product”, says Dr Anjali Mahto, consultant dermatologist and founder of Self London.  

Tachyphylaxis is most likely to happen if you’re taking anti-inflammatory medication, which is why long-term usage is discouraged. However, with products you apply to the skin it can be more complex. “In some cases, the skin may positively adjust to a product – such as becoming more tolerant to retinoids, reducing irritation but still delivering benefits,” says Mahto.

This doesn’t mean your skincare stopped working, it might mean you might not see some of the short-term effects, like redness, but the product will still deliver positive long-term benefits.

“If the skin’s needs change due to ageing, environmental factors or other skincare products in a routine, it may appear that a once-effective product is no longer working. Often, the issue is more about how the skin interacts with the product over time rather than a true loss of efficacy,” she adds. 

Mahto says everything from seasonal shifts to stress and hormones can impact your skin’s response to a product – some are easier to spot than others, for obvious reasons. Although, how long you’ve been using your product is another factor to consider.

“Product stability matters. Ingredients like vitamin C can degrade quickly when exposed to air or light, reducing their potency,” says Mahto. Everything from storage to temperature to sunlight has an impact, so make sure you’re not accidentally speeding up the expiry on your skincare.

As we’ve mentioned, it might not be the product’s fault. Instead, it’s better to analyse your skin. If you’ve noticed your retinol isn’t providing the same smoothing results it once was, it might be time to up your percentage. “Rather than ‘building up resistance’, the skin may simply require a change in formulation – a stronger or weaker concentration – or maybe even a complementary product to maintain results,” says Mahto.

On the other hand, you might have overdone it and left your skin in a compromised position. “Overusing strong active ingredients can compromise the skin barrier, making it less receptive to further treatment,” she says. 

Often it’s not an isolated product causing underwhelming results. “If a serum isn’t working as well as before, I’d argue a reassessment of the overall routine is often needed rather than assuming the product itself is ineffective,” adds Mahto.

This doesn’t mean throwing out all your lotions and potions but having a more targeted and specific approach to your skincare routine. “Adjusting the routine (either by rotating ingredients, increasing or decreasing frequency, or introducing complementary products) can help. For example, if a vitamin C serum seems less effective, combining it with an exfoliant might enhance penetration,” she says.

If you’re worried you’ve overdone it with products, the first port of call will always be to put your skin barrier first and work on getting it healthy and strong. We sound like a broken record but glowing skin always starts with a healthy skin barrier. 

Images: Adobe; Getty