Inclusion Criteria:  frequent or chronic tension type headache according to ICHD-3 with 10 or more headache days per month Headache history of minimum one year. Previously failed treatment with intolerable side-effects to or contra-indications to at least one tension-type headache prophylactic drug Subject agrees to maintain current preventive headache medication regimens (no change in type, frequency, or dose) during the whole study period In case of women of childbearing potential (WOCBP) they have to be using highly effective contraception. Such methods include: combined (oestrogen and progestogen containing) hormonal contraception associated with inhibition of ovulation (oral, intravaginal or transdermal); progestogen-only hormonal contraception associated with inhibition of ovulation (oral, injectable or implantable); intrauterine device (IUD); intrauterine hormone-releasing system (IUS); bilateral tubal occlusion; vasectomised partner; sexual abstinence. This group of patients should not be using other drugs that might interact and reduce the efficacy of the used anticonceptive drug. WOCBP is defined as fertile women, following menarche and until becoming post-menopausal unless permanently sterile. Permanent sterilisation methods include: hysterectomy, bilateral salpingectomy and bilateral oophorectomy. A postmenopausal state is defined as no menses for 12 months without an alternative medical cause. Ability to understand study procedures and to comply with them for the entire length of the study. WOCBP will have to agree to take a pregnancy test before the injection with the study drug Signed informed consent  Exclusion Criteria:  migraine with more than 1 migraine day per month other forms of primary or secondary headaches; including medication overuse headache (MOH) Change in type, dosage or dose frequency of preventive headache or sleep medications < 1 months prior to inclusion Previous exposure at any time to any botulinum toxin serotype Pregnancy, breastfeeding or planned pregnancy Inadequate contraceptive use. Women of childbearing potential (WOCBP) who do not use highly effective contraception (HEC) will be excluded diseases that are contraindications for use of BoNT-A (Myasthenia gravis, Eaton-Lambert syndrome, amyotrophic lateral sclerosis, other diseases interfering with neuromuscular function) or allergy to BoNT-A, or treatment with drugs affecting the neuromuscular junction currently having an active local infection at the sites of injection based on present symptoms. diagnosed with any major infectious processes such as osteomyelitis, or primary or secondary malignancies involving the face that have been active or required treatment in the past 6 months. Serious psychiatric disease that may affect study in opinion of study investigator Other severe chronical pain conditions Ongoing abuse of alcohol or illicit drugs in the opinion of the investigator Participating in another trial that might affect the current study