There are no serious risks as a result of these treatments however its important to look at these facts that need to be considered based on your own circumstances.
Teeth whitening treatments are considered to be safe when procedures are followed as directed. However, there are certain risks associated with whitening that you should be aware of:

Pregnant or lactating women are advised to avoid teeth whitening. The potential impact of swallowed bleach on the foetus or baby is not yet known.  We also recommend the treatment for persons over the age of 16.
Individuals with highly sensitive teeth or those who are in need of dental work should consult their dentist before having a whitening procedure.
If you have a client with any severe allergies like anaphylaxis is best to avoid the treatment as there is no guarantee the products it is made from have not come in contact with or been produced alongside other products.  It’s just not worth the risk.

Our teeth whitening procedure is absolutely hygienic as you never touch your client or their mouth.  The process is effectively a DIY teeth whitening kit with the use of an LED light accelerator to give the client maximum results in less than one hour.  With the kit alone and no accelerator these results would take weeks of continuous treatment.  This accelerated treatment is gentler on teeth and gums as there is less time with tissue exposed to the chemicals.  
For hygiene ensure the client handles their own kit and make sure they have a paper towel or disposable hygienic place to lay the cheek retractor when not in use.

Although rare with our gentle gel, teeth whitening can cause a temporary increase in sensitivity to temperature, pressure and touch.  Persons at most risk for whitening sensitivity are those with gum recession, significant cracks in their teeth or leakage resulting from faulty restorations.  We recommend not offering a teeth whitening treatment to anyone who is currently suffering from a dental condition or who requires dental work.  If excess sensitivity occurs discontinue immediately and ask your client to rinse and make an appointment with their dentist.
Whitening sensitivity usually lasts no longer than a day or two, but in some cases may persist a little longer. We recommend toothpaste for sensitive teeth to reduce sensitivity.

If you have a client with any severe allergies like anaphylaxis is best to avoid the treatment as there is no guarantee the products it is made from have not come in contact with or been produced alongside other products.  It’s just not worth the risk.

If you have a client with diabetes it is important they maintain their blood sugar during the teeth whitening treatment.  When booking the treatment ensure your client brings anything they may need to the appointment.

Clients occasionally experience some degree of gum irritation, usually from applying the gel onto the gum tissue. Such irritation typically lasts from a few minutes after treatment up to several days in the worst case scenario.  The use of the vitamin e swab is very successful in eliminating gum sensitivity.

Teeth whitening will not damage restorations such as bonding, dental crowns or porcelain veneers as long as they are in good condition.  These restorations generally wont change colour when teeth are whitened. This may result in what is referred to as "technicolour teeth".  Most dentists these days whiten teeth prior to creating veneers and bonding however, different coloured teeth can be a issue if this is not the case. We recommend that the client’s teeth be colour checked after the first 20 minute session in these cases, as it may be all that is required to match the restorations.

Blisters generally only happen when the gel comes in contact with the soft tissue whilst under the lamp or is left after the treatment.  There is a link between mouth blisters, swelling and lips with filler.  If your client has lip filler make sure they are extra careful in applying the gel.  Make sure your client waits at least one to two week between the lip filler and a teeth whitening treatment.

It is important when the client applies the gel they avoid the lips and gums, ensure it does not come in contact with the soft tissue of their mouth. If they do get some on there have them remove it with a cotton tip.  Also ensure the cheek retractor being used is large enough to keep the lips from touching the teeth.  We always give you a couple of free large with your order.  Always make sure the client is fully reclined.  If they are not fully reclined they can drool and this can wash the gel onto the soft tissue.  Also make sure the client rinses thoroughly and brushes away any remaining gel with a tooth brush to ensure no gel is left in the mouth.  Get the client to apply the vitamin e at the end of the treatment to their lips gums and the inside of their lips this should help.  Blisters will generally heal within 2 to 3 days.

The risk of blisters and swelling can be reduced by following precautions after the treatment.  Smoking directly after the teeth whitening has been linked to lip blisters and swelling as has the consumption of spicy food and excessively hot foods or beverages.