What happens if I use a higher wattage LED bulb than recommended?

Using a higher wattage LED bulb than recommended can cause problems as a lighting fixture, driver or other connected items will have been tested to confirm the amount of wattage they can handle.  

The wattage rating of a light fitting indicates the maximum power it can safely handle. Whilst LED bulbs use less energy they do still produce a small amount of heat.  This is something that has to be taken into consideration for the fitting and the connected LED bulbs. Exceeding the recommended wattage can cause the fitting to overheat which may damage both the bulb and the light fitting itself.

When it comes to LED lighting it is more relevant to consider lumens to establish the brightness of a bulb rather than wattage.  Lumens are how brightness is measured and as LEDs can use a much lower wattage to produce the same amount of brightness it is better to use this as your reference point rather than the wattage.  Many people mistakenly assume they can increase brightness by using a higher wattage bulb as this was previously the case for halogen and incandescent lighting.

Exceeding the wattage limit of your light fitting can potentially lead to a reduced lifespan for the bulb; reduced lifespan of the fixture due to overheating, risk of electrical damage and voiding the manufacturer's warranty for both the bulb and the light fitting.  This applies doubly to enclosed fittings as the risk is even greater due to limited airflow.

You should always choose a bulb based on the lumen output rather than wattage.  LED technology is ever developing and is only becoming more energy efficient.  You would find for example that if you were looking to replace a LED bulb now there could be an updated version that has a lower wattage than your previous one but it would still have the same amount of lumens.  If you find that you need more light then what your current fixture is offering you should consider using multiple light sources or upgrading the fixture.

You should also make sure that the wattage amount is compatible with any connected dimmers and drivers.  Using higher wattage bulbs than what is stated with these may cause them not to function as expected.