There are basically two types of syringes that can be used to inject methotrexate: U-100 Insulin Syringes or 1cc/1mL syringes. NOTE: 1cc=1mL=U-100 (100 Units)! 3. All of these small syringes are capable of holding a maximum of 25 mg of methotrexate. 4. Needle Length: The syringes all come with needles which are either 5/16â (8 mm=short) or Â½â (12.7 mm) long. 5.