The sensation of feeling cold, experiencing shivers, or having heightened temperature sensitivity is a common phenomenon many people experience leading up to or during their menstrual period. Periods can absolutely cause chills, a reaction often referred to as “period flu” due to its flu-like presentation. This temporary temperature dysregulation is a normal physiological response directly linked to the fluctuations in reproductive hormones throughout the menstrual cycle. The feeling of coldness often signals the beginning of menstruation.
The Core Mechanism: Hormones and Thermoregulation
The primary driver behind temperature changes during the menstrual cycle is the hormone progesterone, which directly influences the body’s internal thermostat. This thermostat, located in a brain region called the hypothalamus, is responsible for maintaining a stable core body temperature. Progesterone has a thermogenic effect, meaning it increases heat production.
Following ovulation, during the luteal phase of the cycle, the body produces high levels of progesterone. This surge causes the hypothalamus to elevate the core basal body temperature (BBT) by a small but significant amount, typically between 0.3°C and 0.7°C. For about two weeks, the body’s internal set point remains at this slightly higher level.
If pregnancy does not occur, progesterone levels sharply decline just before menstruation begins. This sudden hormonal withdrawal causes the hypothalamic set point to drop back down to the lower, pre-ovulatory level. The body perceives this rapid downward shift as a loss of heat, even if the actual temperature change is minor. This regulatory adjustment triggers cold-defense mechanisms, such as shivering and the sensation of chills.
Secondary Physical Factors That Contribute to Chills
While the drop in progesterone is the main cause of thermoregulatory change, other physical factors contribute to the sensation of feeling cold. Prostaglandins, which are hormone-like compounds produced in the uterine lining, play a role in causing uterine contractions to shed the endometrium. These compounds can enter the bloodstream and act systemically throughout the body.
Prostaglandins trigger inflammation and, in high concentrations, can cause systemic symptoms such as muscle aches, joint pain, and fever-like symptoms bundled with chills. The physiological stress of menstruation can also induce temporary fatigue. Heavy menstrual bleeding (menorrhagia) may lead to a mild reduction in iron stores, which can lower a person’s overall energy level and make them more susceptible to feeling cold.
The combination of fatigue and the body’s systemic response to prostaglandins intensifies the cold sensation initiated by the hormonal shift. Severe cramps and poor sleep quality can further deplete the body’s resources, increasing sensitivity to ambient temperature changes.
Practical Strategies for Managing Temperature Swings
Managing menstrual temperature swings involves using simple, direct measures to help the body adjust to the changing thermal set point. The application of external heat can provide comfort and reduce the feeling of chills.
- Layering clothing is an effective strategy, allowing easy regulation of the external environment by adding or removing garments as feelings of coldness or warmth fluctuate.
- Using a heating pad or a hot water bottle on the abdomen or lower back can help warm the core during a chill episode.
- Maintaining adequate hydration is important, as proper fluid balance supports the body’s overall ability to regulate temperature.
- Gentle, light exercise, such as walking or stretching, can improve circulation and naturally generate body heat to counteract the cold sensation.
Identifying When Chills Require Medical Attention
The chills associated with the menstrual cycle are typically mild, short-lived, and not accompanied by a true fever. It is important to distinguish between the normal, hormone-related sensation of coldness and signs of an underlying medical issue. The main indicator that a chill is not simply menstrual is the presence of a sustained, high fever, generally defined as a temperature above 100.4°F (38°C).
If chills are accompanied by a high fever, severe abdominal pain worse than typical cramps, or unusual and foul-smelling vaginal discharge, medical attention should be sought. These symptoms may suggest an infection, such as pelvic inflammatory disease, or other serious conditions requiring diagnosis and treatment. Chills that persist long after the period has ended or interfere significantly with daily activities are also reasons to consult a healthcare provider.