After treatment and risks

Day of injection

Pain, swelling, redness and bruising may occur at the injection sites. Needle-related pain or anxiety can cause fainting.[1]

Days 1 to 4

In an open-label study, 48% of patients noticed an effect by day 1. Physicians saw onset in 87% by day 2 and in all by day 4. The effect builds through the first week.[1][2]

Week 1 to 2

Adverse reactions usually appear in the first week. Eyelid ptosis, when it occurs, starts 3 to 14 days after injection.[1][2]

Day 30

In the Botox Cosmetic frown-line trials, 80% of treated patients had none or mild lines at maximum frown at day 30, against 3% on placebo.[1]

Months 3 to 4

The share with none or mild frown lines fell to 48% at day 90 and 25% at day 120. Daxxify held none or mild lines for a median of about 24 weeks.[1][2]

Repeat treatment

Labels advise retreatment no more often than every 3 months. The lowest effective dose at the longest feasible interval may reduce the chance of antibodies.[1][2][3]

Eyelid ptosis

A drooping upper lid followed 3% of Botox Cosmetic frown-line treatments and 2% of Daxxify treatments in trials. It starts 3 to 14 days after injection and resolves as the toxin wears off. Eye drops such as apraclonidine or oxymetazoline can partly reverse it.[1][2][3]

Brow ptosis

A dropped brow followed 2% of Botox Cosmetic forehead treatments and 0.7% of Xeomin upper face treatments. Forehead lines are treated together with frown lines to reduce this risk.[1][2]

Headache

Headache followed 9% of Botox Cosmetic forehead treatments, and 6% of Daxxify treatments against 2% on placebo. Pooled trials put the risk at 1.45 times placebo.[1][2][3]

Bruising

Injection site bruising followed 2% of Xeomin upper face treatments, against 1% on placebo. In a meta-analysis of 32 trials, bruising occurred at similar rates after toxin and placebo.[1][2]

Spread of toxin effect (boxed warning)

All six US labels carry a boxed warning that the effect may spread beyond the injection site, hours to weeks later, causing weakness, double vision, drooping lids or trouble swallowing or breathing. The Botox Cosmetic label reports no definitive serious cases of distant spread at the labeled cosmetic doses.[1][2][3]

Antibodies and loss of effect

In Botox Cosmetic crow's feet trials, 1.5% of 916 subjects formed binding antibodies and none formed neutralizing antibodies. Across 5,876 subjects in Botox trials, 0.5% formed neutralizing antibodies. Higher doses and shorter intervals may raise the risk.[1][2]

Dry eye and eye changes

Dry eye has been reported after injection in or near the muscle around the eye. Pooled trials found eyelid or eyebrow malposition 3.55 times more often than with placebo.[1][2]

Allergy and who should not be treated

Labels list allergy to any botulinum toxin product and infection at the injection site as reasons not to treat. Dysport may contain cow's milk protein. Botox Cosmetic contains human albumin.[1][2]