According to ASPS (American Society of Plastic Surgeons) statistics, 855,000 people had Botox injections in 2001.

Randomized Double Blind Studies¹
In a double blind study, 405 people aged 18 to 75 were administered Botox Cosmetic and evaluated in randomixed, placebo-controlled clinical studies.

Adverse Event (in order of decreasing frequency for Botox Cosmetic)	Botox N=405	Placebo N=130
Overall	177 (43.7%)	54 (41.5%)
Body as a Whole
Headache	54 (13.3%)	23 (17.7%)
Pain in Face	9 (2.2%)	1 (0.8%)
Flu Syndrome	8 (2.0%)	2 (1.5%)
Pain at Injection Site	7 (1/7%)	1 (0.8%)
Edema at Injection Site	6 (1.5%)	3 (2.3%)
Pain in Back	4 (1.0%)	3 (2.3%)
Injury Accidental	3 (0.7%)	1 (0.8%)
Respiratory System
Infection	14 (3.5%)	5 (3.8%)
Bronchitis	6 (1.5%)	1 (0.8%)
Sinusitus	6 (1.5%)	1 (0.8%)
Pharyngitis	5 (1.2 %)	2 (1.5%)
Dyspnea	3 (0.7%)	0 (0.0%)
Infection Sinus	3 (0.7%)	2 (1.5%)
Layrngitis	3 (0.7%)	0 (0.0%)
Rhinitis	3 (0.7%)	2 (1.5%)
Skin and Appendages
Erythema	7 (1.7%)	2 (1.5%)
Skin Tightness	4 (1.0%)	0 (0.0%)
Irritation Skin	3 (0.7%)	0 (0.0%)
Digestive System
Nausea	12 (3.0%)	3 (2.3%)
Dyspepsia	4 (1.0%)	0 (0.0%)
Tooth Disorder	4 (1.0%)	0 (0.0%)
Liver Function Abnormal	3 (0.7%)	2 (1.5%)
Special Senses
Blepharoptosis	13 (3.2%)	0 (0.0%)
Nervous System
Dizziness	5 (1.2%)	2 (1.5%)
Paresthesia	4 (1.0%)	1 (0.8%)
Anxiety	3 (0.7%)	0 (0.0%)
Twitch	3 (0.7%)	0 (0.0%)
Musculoskeletal System
Muscle Weakness	8 (2.0%)	0 (0.0%)
Urogenital System
Infection Urinary Tract	4 (1.0%)	1 (0.8%)
Hemic and Lymphatic System
Ecchymosis	7 (1.7%)	3 (2.3%)
Cardiovascular
Hypertension	4 (1.0%)	0 (0.0%)

¹ Botox Cosmetic Package Insert

For more information, check out Botox Information, the FDA Article on Botox Cosmetic Treatments and Botox Injections Before and After Photos.