Hypoallergenic dogs are the center of many different big debates among dog lovers and breeders everywhere. The biggest question is probably whether or not they are actually hypoallergenic. A study by Henry Ford Hospital studied dust samples in homes with newborn babies, comparing allergen levels of the homes, each with only one dog. "Scheme A compared purebred hypoallergenic dogs to purebred non-hypoallergenic dogs; Scheme B compared purebred and mixed breed dogs with at least one hypoallergenic parent to purebred non-hypoallergenic dogs; Scheme C compared purebred and mixed breed dogs with at least one hypoallergenic parent to purebred and mixed breed dogs with no known hypoallergenic component; Scheme D compared only purebred dogs identified as hypoallergenic by the American Kennel Club to all other dogs." This study found no scientific basis to suggest that hypoallergenic dogs really do have less allergens.
Hypoallergenic dogs are said to shed less, and produce less saliva and dander. Just because they produce less does not mean that they are completely hypoallergenic. Although the smaller amount of hair, dander, and saliva could help to reduce reactions from allergy sufferers, your dog's kisses could still cause you welts, but there may be less breathing reactions because the hair and dander is not floating around your home as much. Of course, even though hypoallergenic dogs produce less saliva, they still produce saliva, and if it's the saliva that is the allergy problem, there will still be a problem. Even though they shed less, hypoallergenic dogs still have fur (even hairless dogs usually have some fur), so petting the dog or cuddling with him may still cause an allergic reaction. And even though they have less dander, there is still dander produced, so again, petting and cuddling may be a problem still.
Regardless of whether hypoallergenic dogs are better for allergy sufferers or not, some people still believe that mixed breed dogs are hypoallergenic, as long as at least one of the breeds the dog is mixed with is hypoallergenic. Of course, if two "hypoallergenic" dog breeds are bred to produce a hybrid of say, a Shih Tzu/Poodle, the puppies will shed less, and produce less dander and saliva than non-hypoallergenic dog breeds, just as their parents would. The problem with mixing one of these hypoallergenic breeds with a dog that is not considered hypoallergenic is that the breeder can't know which puppies will get which parent's genes. For example, many breeders and pet stores boast about their designer "hypoallergenic" hybrid (mixed) breeds. If these dogs are a mixture of a dog that is hypoallergenic, such as a Shih Tzu, and a non-hypoallergenic breed, such as a Dachshund, there is no guarantee that all, or even any, of their puppies will be hypoallergenic. Because the puppies will receive a mixture of both parents' genes, it is unclear when breeding the parents which genes the puppies will receive. Some of the puppies might end up hypoallergenic, some less allergenic, and some completely non-hypoallergenic.
So, of course, it is not completely impossible to end up with a less allergenic Shweenie (Shih Tzu/Dachshund mix), but when breeders promise that because there is Shih Tzu in the mix, the puppies will have Shih Tzu fur and be hypoallergenic, there is no way they could know that all (or any) of their puppies will even have Shih Tzu fur. In the same way all of the puppies will not look like exactly their mother or their father, their genes will not all be the same. Looking at one litter of puppies, they all might look different. Some of the puppies might look like mom, some might look like dad, and some might be a mix of both. This is the same thing with the hypoallergenic genes. It will depend on that specific dog, and it will also depend on the strength of the person's allergies. Sometimes having slightly less fur floating around is enough to help ease the symptoms of allergies, but sometimes it's not.
So many dogs end up dumped in shelters because their owners' or their owners' kids' allergies were worst than they thought, or because the dog they thought would be hypoallergenic wasn't. If you're a severe allergy sufferer, try a trial foster to adopt situation, where the dog can stay with your family for a few days. This way, you can hold, pet, cuddle, and kiss the puppy or dog and see how your allergies are. Sometimes allergies will get worst as the fur begins to settle, so even this isn't a guarantee. It really just depends how bad the allergies are and how much each individual can suffer through to have a companion to determine whether a severe allergy sufferer can handle having a dog. There are also plenty of allergy medicines that can help those of you who are allergy sufferers who want a dog. Some of these medications can make dog-related breathing problems completely non-existent. Different things can work for different people, but homework should be done before trusting people that promise hypoallergenic designer mixed breed dogs.