I'm afraid I don't want to assume on this one Stephen, so I need to ask some questions, and they might pay for you to ask your customer:
1. What do they believe they are allergic to? Or did an allergist suggest that they were allergic to something?
Reason: Some people confuse "chemical sensitivity" to "allergies", and they aren't the same thing at all.
2. Is it an allergy to dogs, cats, cockroaches, or dustmites? If they are allergic to cat or dog danders, cockroach feces, or dustmite danders/exoskeletons, then the Masterblend treatment has been effective for this problem, but the related anti allergen cleaners themselves will not take care of the problem alone. Cleaning will reduce the materials present, but not remove all of them. You will need to apply their allergy relief treatment after cleaning as well.
Dustmites are more likely to be present on the mattress and bedding materials, and possibly upholstery that is frequently used and slept on. They need a humid and warm environment to thrive, which the human body provides by its regular contact to bed and some furnishings, but not as likely to carpet.
Dogs, cats, and cockroaches will leave residues over a more widespread area, including carpet, and as such are not limited to beds and furnishings, though many pets sleep with pet owners. (If Jimmy Ladwig is reading, I cannot wait for his rant on this subject!)
Also bear in mind that the treatment may cause resoiling, but the customer will usually find enough relief that they won't mind.
Even if they don't have pets in the home, if they are just moving into a home that had a pet, they may need the treatment.
To your initial question: You won't need anti allergen products if they just want cleaning, and if there is no evidence of all of the above mentioned issues. They just need a good "H.E.P.A. vacuuming" and hot water extraction with the exhaust of the vacuum outside of the home (no portables). You might want a "low or no odor" product for your cleaning process just in case what they are calling "allergies' is really sensitivity to perfume oil or solvents.
I've had many cases where previous cleaning was sub par, carpet loaded with cleaning residue, dust etc., and I suspect the landlord may have cut too many corners. In these cases the good cleaning alone solved all problems.
