I have large jaw muscles and i want to slim it, but is there a way without botox?

Not really: Botox is a relatively simple way to reduce jaw muscle fullness.

Jaw reduction: Botox is a wonderful way to reduce a strong jawline due to prominent jaw muscles. Other than botox, surgery is the only other way to address the area. If Botox is appropriate, i would try that first, and consider surgery only if your desired results can't be obtained.

Masseter Hypertrophy: Enlarged masseter muscles can be treated with Botox to help reduce, over time, the bulk of the muscle. People who have a primary problem of clenching their jaw or grinding their teeth, may want to seek advice from a dentist to be fit for a night guard to help prevent this. I don't know of any other good interventions, however.

Unknown: The only known way, to date, is with Botox or other botulinum toxins.

Not really: Botox is very effective for this. It is a very common procedure in asia where large jaw muscles are considered unattractive. It is not fda approved for this indication so treatment would be considered "off label.".

Large Jaw Muscles: If botox is not giving you the results you anticipated, there are a couple of surgical options. Keep in mind, this will begin a discussion which hopefully you will continue with a surgeon experienced in these types of procedures. Reduction of the muscle itself (masseter) is one option, and also reduction of the underlying bone (mandible contouring) is another option. Usually done in conjunction.

Masseter hypertrophy: Masseteric hypertrophy is a relatively uncommon, idiopathic condition that can occur unilaterally or bilaterally. Non-surgical modalities of treatment include tranquilizers or muscle relaxants, pain psychology (CBT) and injection of very small doses of botulinum toxin type A.

Jaw slimming: The other alternative is surgery.

Large Jaw Muscles: Botox or other neuromodulator injection is the most non invasive treatment. The other option is surgery.

Prevention: Most "large jaw muscles" are secondary to bruxism. See a TMJ expert. If you can control the bruxism, the muscle size will decrease without other treatment.