Side effects of anxiety medications can relate to altered cardiovascular or kidney function and lead to additional cardiovascular problems, increased risk of injury, and difficulty breathing.

Anti-anxiety medications are often given to cats in order to negate the stress felt during major events such as long-distance travel and recovery from major surgery. Anti-anxiety drugs can also be used for training and behavioral modification in extreme circumstances. Although these drugs are very effective for their intended purpose, they can have some side effects that cat owners should be aware of prior to using such medication on their pet.

If a cat is using anti-anxiety drugs and is experiencing side effects, they will typically be quite noticeable. Although some side effects are quite minor, others can have a very serious impact on the cat's health. 

The types of medications available to treat anxiety can be generally divided into tranquilizers and SSRIs (Selective Serotonin Reuptake Inhibitors). Tranquilizers are designed to actively sedate the animal they are given to, and whilst in most cats they will produce mild effects, their impact on the behavior of others can be much more pronounced. This is due to the unique nature of each individual cat's metabolism, which results in some being more susceptible than others to side effects such as extreme laziness. SSRIs on the other hand, rely on blocking certain chemicals produced by the body from interacting from the brain. This can have unintended consequences, causing changes in the function of different organs and the brain itself (explaining symptoms such as increased urination and loss of balance).

Upon presentation to the clinic, the vet will perform a physical examination of the cat and perform several behavioral tests to check its responses to stimuli. Additionally, the vet will measure the heart rate and breathing pattern of the cat, as this can be indicative of a more serious reaction to the drugs. They will also have questions for the owner regarding any changes they have noticed and will also consult the cat's medical history to make sure that there is not an underlying condition causing the symptoms. Because of this, it is best for the owner to draw up a list of any odd behavior they observe prior to attending the clinic.

Upon tracing the cause of the symptoms to the anti-anxiety medication, the vet will lay out the options available to the owner. If the side effects are benign and relatively mild, they may recommend continuing with the medication. However, in the case of more serious symptoms such as dehydration, the vet will usually opt to place the cat on a different medication or stop the treatment entirely. Different drugs have different chemical makeups and can produce varying side effects, so whilst an alternative medication may fit within the same category as the previous one (i.e. tranquilizer or SSRI), there is no guarantee that the side effects will continue.

In the event that the vet decides to simply halt the use of the drugs, there will be a period during which the cat must be weaned off the drugs. If this is not done, there can be additional side effects including aggression and worsened anxiety. To accomplish this, the vet will usually instruct the owner to gradually reduce the dosage that is being given to the cat over a period of weeks. This will give the cat's body ample time to adjust to the lessened effects.