A non-therapeutic method for skin antiaging treatment which prolongs in time the effects of treatment with Botulinum toxin injections, the method comprising: a. The administration of an effective amount of Botulinum toxin to an area of facial and/or neck skin, b. and the administration, from once a week to ten times a day, of a cosmetic composition comprising a cosmetically effective amount of at least one peptide selected from the group consisting of SEQ ID No.11, SEQ ID No.4, or a sequence of 7 to 12 adjacent amino acids contained in SEQ ID No.4, wherein said sequence comprises the amino acid sequence of SEQ ID No.11, and according to the general formula: R 1 -AA-R 2 its stereoisomers, mixtures thereof, and/or its cosmetically acceptable salts thereof, in which AA is a sequence selected from the group consisting of SEQ ID No.11, SEQ ID No.4, or a sequence of 7 to 12 adjacent amino acids contained in SEQ ID No.4, wherein said sequence comprises the amino acid sequence of SEQ ID No.11; wherein: R 1 is selected from the group consisting of H, substituted or non-substituted non-cyclic aliphatic group, substituted or non-substituted alicyclyl, substituted or non-substituted heterocyclyl, substituted or non-substituted heteroarylalkyl, substituted or non-substituted aryl, substituted or non-substituted aralkyl and R 5 -C -; and R 2 is selected from the group consisting of -NR 3 R 4, -OR 3 and -SR 3; where R 3 and R 4 are independently selected from the group consisting of H, substituted or non-substituted non-cyclic aliphatic group, substituted or non-substituted alicyclyl, substituted or non-substituted heterocyclyl, substituted or non-substituted heteroarylalkyl, substituted or non-substituted aryl and substituted or non-substituted aralkyl; wherein R 5 is selected from the group consisting of H, substituted or non-substituted non-cyclic aliphatic group, substituted or non-substituted alicyclyl, substituted or non-substituted aryl, substituted or non-substituted aralkyl, substituted or non-substituted heterocyclyl and substituted or non-substituted heteroarylalkyl; and at least one cosmetically acceptable excipient or adjuvant. a. The administration of an effective amount of Botulinum toxin to an area of facial and/or neck skin, b. and the administration, from once a week to ten times a day, of a cosmetic composition comprising a cosmetically effective amount of at least one peptide selected from the group consisting of SEQ ID No.11, SEQ ID No.4, or a sequence of 7 to 12 adjacent amino acids contained in SEQ ID No.4, wherein said sequence comprises the amino acid sequence of SEQ ID No.11, and according to the general formula: R 1 -AA-R 2 its stereoisomers, mixtures thereof, and/or its cosmetically acceptable salts thereof, in which AA is a sequence selected from the group consisting of SEQ ID No.11, SEQ ID No.4, or a sequence of 7 to 12 adjacent amino acids contained in SEQ ID No.4, wherein said sequence comprises the amino acid sequence of SEQ ID No.11; R 1 is selected from the group consisting of H, substituted or non-substituted non-cyclic aliphatic group, substituted or non-substituted alicyclyl, substituted or non-substituted heterocyclyl, substituted or non-substituted heteroarylalkyl, substituted or non-substituted aryl, substituted or non-substituted aralkyl and R 5 -C -; and R 2 is selected from the group consisting of -NR 3 R 4, -OR 3 and -SR 3; where R 3 and R 4 are independently selected from the group consisting of H, substituted or non-substituted non-cyclic aliphatic group, substituted or non-substituted alicyclyl, substituted or non-substituted heterocyclyl, substituted or non-substituted heteroarylalkyl, substituted or non-substituted aryl and substituted or non-substituted aralkyl; wherein R 5 is selected from the group consisting of H, substituted or non-substituted non-cyclic aliphatic group, substituted or non-substituted alicyclyl, substituted or non-substituted aryl, substituted or non-substituted aralkyl, substituted or non-substituted heterocyclyl and substituted or non-substituted heteroarylalkyl; and at least one cosmetically acceptable excipient or adjuvant.