My eyes hurt and become red when I wear contacts.
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Instead of defects with the product, these symptoms may arise due to wrong wearing method from lack of experience and dry eyes.
Also, minuscule dust left on the surface of the contacts can cause discomfort and also redden the eyes. Try cleansing the contacts thoroughly and try wearing again. 
If red eyes and pain occur 1~2 hours after the wear, the causes can be attributed to dry eyes. Your eyes will have to rest fully when such symptoms occur.
If you feel uncomfortable during wear, it is best to steadily increase the time of the wear in several occasions. 
Wearing contacts for long time when your eyes are not used to it can only cause discomfort. 
If one individual is the only one undergoing such discomfort, the condition may be caused by the dryness of the eyes. 
(xerophthalmia) People who have xerophthalmia must decrease usage time and also utilize artificial teardrops during wear. 
In order to keep your eyes moist, blinking consciously also helps greatly. 
The eyelids prevent your eyes from drying out and provide humidity while blinking. 
People who have xerophthalmia must be cautious in examining his current condition and decide upon the usage time of the contacts.
It is true that xerophthalmia causes discomfort more to the people with the condition compared to others. Using teardrops can alleviate the experience, and they must refrain from long-time usage.
One must also be cautious not to overuse artificial tear.  
Warning! One should never use eye drops(not artificial tear) when his/her eyes run dry. 
It is better for people to decrease the frequency of wearing contacts during dry seasons, such as fall or winter. Exhausted eyes can easily become drier than one may expect during these seasons. 
When your eyes become red, you should take the contacts off and examine for defects of the contacts, damage to the eyes, their condition and dryness in order to find causes. 
The redness will fade in about a day after you take off the lenses. 
When your eyes are still red and painful, be prompt to consult a professional to receive adequate treatment. 

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