In a test of 141 hormonal contraceptives, Stiftung Warentest found less than half to be suitable.
The testers announced on Wednesday that this is not due to the effectiveness, but to the tolerability.
For hormonal contraception, they advised a pill with the lowest possible estrogen content and the progestins levonorgestel, norethisterone or norgestimate.
With these pills, the risk of thrombosis is lower than with contraceptive pills with other gestagens, explained the testers.
Spirals are also suitable.
They are available with hormones or copper.
Therefore, IUDs do not increase the risk of thrombosis.
They have a long-term effect and are especially recommended for women who have already given birth to a child.
In contrast, the drug experts at Stiftung Warentest do not recommend the three-month injection as a standard contraceptive.
Accordingly, implants, rings and plasters are also less suitable.
The implant is not always easy to remove.
The ring and plaster work like the pill - but there are indications that the risk of thrombosis is higher with both drugs than with suitable birth control pills.